DS1922L_11 MAXIM | Alldatasheet
Document overview
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Technical content
Features
♦ Automatically Wakes Up, Measures Temperature, and Stores Values in 8KB of Data-Log Memory in 8-Bit or 16-Bit Format ♦ Digital Thermometer Measures Temperature with 8-Bit (0.5°C) or 11-Bit (0.0625°C) Resolution ♦ Accuracy of ±0.5°C from -10°C to +65°C (DS1922L), ± 0.5°C from +20°C to +75°C (DS1922T), with Software Corrections ♦ Water Resistant or Waterproof if Placed Inside DS9107 i Button Capsule (Exceeds Water Resistant 3 ATM Requirements) ♦ Sampling Rate from 1s Up to 273hr ♦ Programmable High and Low Trip Points for Temperature Alarms ♦ Programmable Recording Start Delay After Elapsed Time or Upon a Temperature Alarm Trip Point ♦ Quick Access to Alarmed Devices Through 1-Wire Conditional Search Function ♦ 512 Bytes of General-Purpose Memory Plus 64 Bytes of Calibration Memory ♦ Two-Level Password Protection of All Memory and Configuration Registers ♦ Communicates to Host with a Single Digital Signal Up to 15.4kbps at Standard Speed or Up to 125kbps in Overdrive Mode Using 1-Wire Protocol ♦ Operating Temperature Range: DS1922L: -40°C to +85°C; DS1922T: 0°C to +125°C Common iButton Features ♦ Digital Identification and Information by Momentary Contact ♦ Unique Factory-Lasered 64-Bit Registration Number Ensures Error-Free Device Selection and Absolute Traceability Because No Two Parts Are Alike ♦ Built-In Multidrop Controller for 1-Wire Net ♦ Chip-Based Data Carrier Compactly Stores Information ♦ Data Can Be Accessed While Affixed to Object ♦ Button Shape is Self-Aligning with Cup-Shaped Probes ♦ Durable Stainless-Steel Case Engraved with Registration Number Withstands Harsh Environments ♦ Easily Affixed with Self-Stick Adhesive Backing, Latched by Its Flange, or Locked with a Ring Pressed Onto Its Rim ♦ Presence Detector Acknowledges When Reader First Applies Voltage ♦ Meets UL 913, 5th Ed., Rev. 1997-02-24; Intrinsically Safe Apparatus: Approved Under Entity Concept for Use in Class I, Division 1, Group A, B, C, and D Locations
Ordering Information
#Denotes a RoHS-compliant device that may include lead(Pb) that is exempt under the RoHS requirements. Pin Configuration appears at end of data sheet. PART TEMP RANGE PIN-PACKAGE DS1922L-F5# -40°C to +85°C F5 i Button DS1922T-F5# 0°C to +125°C F5 i Button Examples of Accessories iButton and 1-Wire are registered trademarks of Maxim Integrated Products, Inc. PART ACCESSORY DS9096P Self-Stick Adhesive Pad DS9101 Multipurpose Clip DS9093RA Mounting Lock Ring DS9093A Snap-in FOB DS9092 i Button Probe
Temperature Logger iButton with 8KB Data-Log Memory ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VPUP = +3.0V to +5.25V.) Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Operating Temperature Range Storage Temperature Range* PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS DS1922L (Note 1) -40 +85 Operating Temperature T A DS1922T (Note 1) 0 +125 IO PIN: GENERAL DATA 1-Wire Pullup Resistance R PUP (Notes 2, 3) 2.2 k Input Capacitance C IO (Note 4) 100 800 pF Input Load Current I L IO pin at VPUP 6 10 μA High-to-Low Switching Threshold V TL (Notes 5, 6) 0.4 3.2 V Input Low Voltage V IL (Notes 2, 7) 0.3 V Low-to-High Switching Threshold V TH (Notes 5, 8) 0.7 3.4 V Switching Hysteresis V HY (Note 9) 0.09 N/A V Output Low Voltage V OL At 4mA (Note 10) 0.4 V Standard speed, RPUP = 2.2k 5 Overdrive speed, R PUP = 2.2k 2Recovery Time (Note 2) t REC Overdrive speed, directly prior to reset pulse; R PUP = 2.2k 5 μs Rising-Edge Hold-Off Time t REH (Note 11) 0.6 2.0 μs Standard speed 65 Overdrive speed, VPUP > 4.5V 8 Time-Slot Duration (Note 2) t SLOT Overdrive speed (Note 12) 9.5 μs IO PIN: 1-Wire RESET, PRESENCE-DETECT CYCLE Standard speed, VPUP > 4.5V 480 720 Standard speed (Note 12) 690 720 Overdrive speed, VPUP > 4.5V 48 80 Reset Low Time (Note 2) t RSTL Overdrive speed (Note 12) 70 80 μs Standard speed, VPUP > 4.5V 15 60 Standard speed (Note 12) 15 63.5 Presence-Detect High Time t PDH Overdrive speed (Note 12) 2 7 μs Standard speed, VPUP > 4.5V 1.5 5 Standard speed 1.5 8Presence-Detect Fall Time (Note 13) tFPD Overdrive speed 0.15 1 μs *Storage or operation above +50°C significantly reduces battery life.
Temperature Logger iButton with 8KB Data-Log Memory ELECTRICAL CHARACTERISTICS (continued) (VPUP = +3.0V to +5.25V.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Standard speed, VPUP > 4.5V 60 240 Standard speed (Note 12) 60 287 Overdrive speed, VPUP > 4.5V (Note 12) 7 24 Presence-Detect Low Time t PDL Overdrive speed (Note 12) 72 8 μs Standard speed, VPUP > 4.5V 65 75 Standard speed 71.5 75Presence-Detect Sample Time (Note 2) tMSP Overdrive speed 8 9 μs IO PIN: 1-Wire WRITE Standard speed 60 120 Overdrive Speed, VPUP > 4.5V (Note 12) 6 12Write-Zero Low Time (Notes 2, 14) tW0L Overdrive speed (Note 12) 7.5 12 μs Standard speed 5 15 Write-One Low Time (Notes 2, 14) tW1L Overdrive speed 1 1.95 μs IO PIN: 1-Wire READ Standard speed 5 15 - Read Low Time (Notes 2, 15) tRL Overdrive speed 1 1.95 - μs Standard speed t RL + 15 Read Sample Time (Notes 2, 15) tMSR Overdrive speed t RL + 1.95 μs REAL-TIME CLOCK Accuracy See RTC Accuracy graphs min/ month -40°C to +85°C -300 +60 Frequency Deviation F 0°C to +125°C -600 +60 PPM TEMPERATURE CONVERTER 8-bit mode 30 75 Conversion Time (Note 16) tCONV 16-bit mode (11 bits) 240 600 ms Thermal Response Time Constant (Note 17) RESP i Button package 130 s Conversion Error Without Software Correction (Notes 18, 19) See Temperature Accuracy graphs °C Conversion Error with Software Correction (Notes 19, 20) See Temperature Accuracy graphs °C Note 1: Guaranteed by design, not production tested to -40°C or +125°C. Note 2: System requirement. Note 3: Maximum allowable pullup resistance is a function of the number of 1-Wire devices in the system and 1-Wire recovery times. The specified value here applies to systems with only one device and with the minimum 1-Wire recovery times. For more heavily loaded systems, an active pullup such as that found in the DS2480B may be required. Note 4: Capacitance on the data pin could be 800pF when VPUP is first applied. If a 2.2kΩ resistor is used to pull up the data line, 2.5µs after VPUP has been applied, the parasite capacitance does not affect normal communications. Note 5: VTL and VTH are functions of the internal supply voltage, which is a function of VPUP and the 1-Wire recovery times. The VTH and VTL maximum specifications are valid at VPUP = 5.25V. In any case, VTL < VTH < VPUP. Note 6: Voltage below which, during a falling edge on IO, a logic 0 is detected.
Note 7: The voltage on IO must be less than or equal to VILMAX whenever the master drives the line low. Note 8: Voltage above which, during a rising edge on IO, a logic 1 is detected. Note 9: After VTH is crossed during a rising edge on IO, the voltage on IO must drop by VHY to be detected as logic 0. Note 10: The I-V characteristic is linear for voltages less than 1V. Note 11: The earliest recognition of a negative edge is possible at tREH after VTH has been previously reached. Note 12: Numbers in bold are not in compliance with the published iButton standards. See the Comparison Table. Note 13: Interval during the negative edge on IO at the beginning of a presence-detect pulse between the time at which the voltage is 90% of VPUP and the time at which the voltage is 10% of VPUP. Note 14: ε in Figure 13 represents the time required for the pullup circuitry to pull the voltage on IO up from VIL to VTH. The actual maximum duration for the master to pull the line low is tW1LMAX + tF - ε and tW0LMAX + tF - ε, respectively. Note 15: δ in Figure 13 represents the time required for the pullup circuitry to pull the voltage on IO up from VIL to the input-high threshold of the bus master. The actual maximum duration for the master to pull the line low is tRLMAX + tF. Note 16: To conserve battery power, use 8-bit temperature logging whenever possible. Note 17: This number was derived from a test conducted by Cemagref in Antony, France, in July 2000: Note 18: Includes +0.1/-0.2°C calibration chamber measurement uncertainty. Note 19: Warning: Not for use as the sole method of measuring or tracking temperature in products and articles that could affect the health or safety of persons, plants, animals, or other living organisms, including but not limited to foods, beverages, pharmaceuticals, medications, blood and blood products, organs, flammable, and combustible products. User shall assure that redundant (or other primary) methods of testing and determining the handling methods, quality, and fitness of the articles and products should be implemented. Temperature tracking with this product, where the health or safety of the aforementioned persons or things could be adversely affected, is only recommended when supplemental or redundant information sources are used. Data-logger products are 100% tested and calibrated at time of manufacture by Maxim to ensure that they meet all data sheet parameters, including temperature accuracy. User shall be responsible for proper use and storage of this product. As with any sensor-based product, user shall also be responsible for occasionally rechecking the temperature accuracy of the product to ensure it is still operating properly. Note 20: Assumes using calibration memory with calibration equations for error compensation. Includes +0.1/-0.2°C calibration chamber measurement uncertainty. Guaranteed by design. Temperature Logger iButton with 8KB Data-Log Memory COMPARISON TABLE LEGACY VALUES DS1922L/DS1922T VALUES STANDARD SPEED (μs) OVERDRIVE SPEED (μs) STANDARD SPEED (μs) OVERDRIVE SPEED (μs) PARAMETER MIN MAX MIN MAX MIN MAX MIN MAX tSLOT (including tREC) 61 (undefined) 7 (undefined) 65 (undefined) 9.5 (undefined) tRSTL 480 (undefined) 48 80 690 720 70 80 tPDH 15 60 2 6 15 63.5 2 7 tPDL 60 240 8 24 60 287 7 28 tW0L 60 120 6 16 60 120 7.5 12 *Intentional change; longer recovery time requirement due to modified 1-Wire front-end. Note: Numbers in bold are not in compliance with the published iButton standards. iButton CAN PHYSICAL SPECIFICATION SIZE See the Package Information section. WEIGHT Ca. 3.3 grams SAFETY Meets UL 913, 5th Ed., Rev. 1997-02-24; Intrinsically Safe Apparatus, approval under Entity Concept for use in Class I, Division 1, Group A, B, C, and D Locations. ELECTRICAL CHARACTERISTICS (continued) (VPUP = +3.0V to +5.25V.)
Temperature Logger iButton with 8KB Data-Log Memory DS1922L Minimum Product Lifetime vs. Temperature, Slow Sampling -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 8-BIT MINIMUM PRODUCT LIFETIME (YEARS) TEMPERATURE (°C) EVERY MINUTE NO SAMPLES EVERY 10 MINUTES EVERY 60 MINUTES EVERY 3 MINUTES OSCILLATOR OFF 11-BIT MINIMUM PRODUCT LIFETIME (YEARS) -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) EVERY MINUTE NO SAMPLES EVERY 10 MINUTES EVERY 60 MINUTES EVERY 3 MINUTES OSCILLATOR OFF EVERY 30 MINUTES EVERY 300 MINUTES
Temperature Logger iButton with 8KB Data-Log Memory DS1922L Minimum Product Lifetime vs. Temperature, Fast Sampling 100 150 200 250 300 350 8-BIT MINIMUM PRODUCT LIFETIME (DAYS) -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) EVERY SECOND EVERY 30 SECONDS EVERY 10 SECONDSEVERY 3 SECONDS EVERY 60 SECONDS 100 11-BIT MINIMUM PRODUCT LIFETIME (DAYS) -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) EVERY SECOND EVERY 30 SECONDS EVERY 10 SECONDSEVERY 3 SECONDS EVERY 60 SECONDS
Temperature Logger iButton with 8KB Data-Log Memory DS1922T Minimum Product Lifetime vs. Temperature, Slow Sampling 8-BIT MINIMUM PRODUCT LIFETIME (YEARS) 0 10 20 30 40 50 60 70 80 90 100 110 120 TEMPERATURE (°C) NO SAMPLESEVERY 60 MINUTES EVERY 10 MINUTESEVERY MINUTE EVERY 3 MINUTES OSCILLATOR OFF 11-BIT MINIMUM PRODUCT LIFETIME (YEARS) 0 10 20 30 40 50 60 70 80 90 100 110 120 TEMPERATURE (°C) NO SAMPLESEVERY 60 MINUTES EVERY 10 MINUTESEVERY MINUTE EVERY 3 MINUTES OSCILLATOR OFF EVERY 30 MINUTES EVERY 300 MINUTES
Temperature Logger iButton with 8KB Data-Log Memory DS1922T Minimum Product Lifetime vs. Temperature, Fast Sampling 100 150 200 250 300 350 8-BIT MINIMUM PRODUCT LIFETIME (DAYS) 0 10 20 30 40 50 60 70 80 90 100 110 120 TEMPERATURE (°C) EVERY 30 SECONDS EVERY 10 SECONDSEVERY SECOND EVERY 3 SECONDS EVERY 60 SECONDS 100 11-BIT MINIMUM PRODUCT LIFETIME (DAYS) 0 10 20 30 40 50 60 70 80 90 100 110 120 TEMPERATURE (°C) EVERY 30 SECONDS EVERY 10 SECONDSEVERY SECOND EVERY 3 SECONDS EVERY 60 SECONDS
Temperature Logger iButton with 8KB Data-Log Memory DS1922L Minimum Product Lifetime vs. Sample Rate 0.01 0.01 0.1 1 10 100 0.1 MINUTES BETWEEN SAMPLES 8-BIT MINIMUM PRODUCT LIFETIME (YEARS) +85°C +75°C +60°C -40°C +40°C 0°C 0.01 0.1 1 10 100 MINUTES BETWEEN SAMPLES 0.001 0.01 0.1 11-BIT MINIMUM PRODUCT LIFETIME (YEARS) +85°C +75°C +60°C -40°C +40°C 0°C
Temperature Logger iButton with 8KB Data-Log Memory DS1922T Minimum Product Lifetime vs. Sample Rate 0.01 0.01 0.1 1 10 100 0.1 MINUTES BETWEEN SAMPLES 8-BIT MINIMUM PRODUCT LIFETIME (YEARS) +125°C +110°C +95°C +85°C +75°C +60°C +40°C 0°C 0.001 0.01 0.1 0.01 0.1 1 10 100 MINUTES BETWEEN SAMPLES 11-BIT MINIMUM PRODUCT LIFETIME (YEARS) +125°C +110°C +95°C +85°C +75°C +60°C +40°C 0°C
Temperature Logger iButton with 8KB Data-Log Memory DS1922L Temperature Accuracy -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 ERROR (°C) -40 NOTE: THE GRAPHS ARE BASED ON 11-BIT DATA. -30 -20 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) UNCORRECTED MAXIMUM ERROR UNCORRECTED MINIMUM ERROR SW CORRECTED MAXIMUM ERROR SW CORRECTED MINIMUM ERROR DS1922T Temperature Accuracy -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 ERROR (°C) NOTE: THE GRAPHS ARE BASED ON 11-BIT DATA. 10 20 30 40 50 60 70 80 90 100 110 120 TEMPERATURE (°C) UNCORRECTED MAXIMUM ERROR UNCORRECTED MINIMUM ERROR SW CORRECTED MAXIMUM ERROR SW CORRECTED MINIMUM ERROR
Temperature Logger iButton with 8KB Data-Log Memory DS1922L RTC Accuracy (Typical) -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 DRIFT (MINUTES/MONTH) -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) DS1922T RTC Accuracy (Typical) -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 DRIFT (MINUTES/MONTH) 0 1 02 0 3 04 05 06 07 08 09 0 1 0 0 1 1 0 1 2 0 TEMPERATURE (°C)
Figure 1. Block Diagram
Figure 6. Register Pages Map
Figure 6. Register Pages Map (continued)
Temperature Logger iButton with 8KB Data-Log Memory Detailed Register Descriptions Timekeeping and Calendar The RTC and calendar information is accessed by reading/writing the appropriate bytes in the register page, address 0200h to 0205h. For readings to be valid, all RTC registers must be read sequentially start- ing at address 0200h. Some of the RTC bits are set to 0. These bits always read 0 regardless of how they are written. The number representation of the RTC registers is binary-coded decimal (BCD) format. The DS1922L/DS1922T’s RTC can run in either 12hr or 24hr mode. Bit 6 of the Hours register (address 0202h) is defined as the 12hr- or 24hr-mode select bit. When high, the 12hr mode is selected. In the 12hr mode, bit 5 is the AM/PM bit with logic 1 being PM. In the 24hr mode, bit 5 is the 20hr bit (20hr to 23hr). The CENT bit, bit 7 of the Months register, can be written by the user. This bit changes its state when the years counter transi- tions from 99 to 00. The calendar logic is designed to automatically com- pensate for leap years. For every year value that is either 00 or a multiple of 4, the device adds a 29th of February. This works correctly up to (but not including) the year 2100. Sample Rate The content of the Sample Rate register (addresses 0206h, 0207h) specifies the time elapse (in seconds if EHSS = 1, or minutes if EHSS = 0) between two tem- perature-logging events. The sample rate can be any value from 1 to 16,383, coded as an unsigned 14-bit binary number. If EHSS = 1, the shortest time between logging events is 1s and the longest (sample rate = 3FFFh) is 4.55hr. If EHSS = 0, the shortest is 1min and the longest time is 273.05hr (sample rate = 3FFFh). The EHSS bit is located in the RTC Control register at address 0212h. It is important that the user sets the EHSS bit accordingly while setting the Sample Rate register. Writing a sample rate of 0000h results in a sample rate = 0001h, causing the DS1922L/DS1922T to log the temperature either every minute or every second depending upon the state of the EHSS bit. Sample Rate Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0206h Sample Rate Low 0207h 0 0 Sample Rate High RTC Registers Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0200h 0 10 Seconds Single Seconds 0201h 0 10 Minutes Single Minutes 0202h 0 12/24 20 Hour AM/PM 10 Hour Single Hours 0203h 0 0 10 Date Single Date 0204h CENT 0 0 10 Months Single Months 0205h 10 Years Single Years Note: During a mission, there is only read access to these registers. Bit cells marked “0” always read 0 and cannot be written to 1. Note: During a mission, there is only read access to these registers. Bit cells marked “0” always read 0 and cannot be written to 1.
0000h when too cold and FFh or FFE0h when too hot. address 0208h; High Alarm address 0209h). sion is used to determine whether an alarm is generated. Table 1. Temperature Conversion Examples Table 2. Temperature Alarm Threshold Examples
Temperature Logger iButton with 8KB Data-Log Memory Temperature Sensor Alarm The DS1922L/DS1922T have two Temperature Alarm Threshold registers (address 0208h, 0209h) to store values that determine whether a critical temperature has been reached. A temperature alarm is generated if the device measures an alarming temperature and the alarm signaling is enabled. The bits ETLA and ETHA that enable the temperature alarm are located in the Temperature Sensor Control register. The temperature alarm flags TLF and THF are found in the Alarm Status register at address 0214h. Bit 1: Enable Temperature High Alarm (ETHA). This bit controls whether, during a mission, the temperature high alarm flag (THF) can be set, if a temperature con- version results in a value equal to or higher than the value in the Temperature High Alarm Threshold register. If ETHA is 1, temperature high alarms are enabled. If ETHA is 0, temperature high alarms are not generated. Bit 0: Enable Temperature Low Alarm (ETLA). This bit controls whether, during a mission, the temperature low alarm flag (TLF) can be set, if a temperature con- version results in a value equal to or lower than the value in the Temperature Low Alarm Threshold register. If ETLA is 1, temperature low alarms are enabled. If ETLA is 0, temperature low alarms are not generated. RTC Control To minimize the power consumption of the DS1922L/ DS1922T, the RTC oscillator should be turned off when these devices are not in use. The oscillator on/off bit is located in the RTC Control register. This register also includes the EHSS bit, which determines whether the sample rate is specified in seconds or minutes. Bit 1: Enable High-Speed Sample (EHSS). This bit controls the speed of the sample rate counter. When set to logic 0, the sample rate is specified in minutes. When set to logic 1, the sample rate is specified in seconds. Bit 0: Enable Oscillator (EOSC). This bit controls the crystal oscillator of the RTC. When set to logic 1, the oscillator starts. When written to logic 0, the oscillator stops and the device is in a low-power data-retention mode. This bit must be 1 for normal operation. A Forced Conversion or Start Mission command automati- cally starts the RTC by changing the EOSC bit to logic 1. Temperature Sensor Control Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0210h 0 0 0 0 0 0 ETHA ETLA RTC Control Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0212h 0 0 0 0 0 0 EHSS EOSC Note: During a mission, there is only read access to this register. Bits 2 to 7 have no function. They always read 0 and cannot be written to 1. Note: During a mission, there is only read access to this register. Bits 2 to 7 have no function. They always read 0 and cannot be written to 1.
Temperature Logger iButton with 8KB Data-Log Memory Mission Control The DS1922L/DS1922T are set up for operation by writ- ing appropriate data to the special function registers, which are located in the two register pages. The set- tings in the Mission Control register determine which format (8 or 16 bits) applies and whether old data can be overwritten by new data once the data-log memory is full. An additional control bit can be set to tell the DS1922L/DS1922T to wait with logging data until a tem- perature alarm is encountered. Bit 5: Start Mission Upon Temperature Alarm (SUTA). This bit specifies whether a mission begins immediately (includes delayed start) or if a temperature alarm is required to start the mission. If this bit is 1, the device performs an 8-bit temperature conversion at the selected sample rate and begins with data logging only if an alarming temperature (high alarm or low alarm) was found. The first logged temperature is when the alarm occurred. However, the mission sample counter does not increment. This functionality is guaranteed by design and not production tested. Bit 4: Rollover Control (RO). This bit controls whether, during a mission, the data-log memory is overwritten with new data or whether data logging is stopped once the data-log memory is full. Setting this bit to 1 enables the rollover and data logging continues at the begin- ning, overwriting previously collected data. If this bit is 0, the logging and conversions stop once the data-log memory is full. However, the RTC continues to run and the MIP bit remains set until the Stop Mission command is performed. Bit 2: Temperature Logging Format Selection (TLFS). This bit specifies the format used to store tem- perature readings in the data-log memory. If this bit is 0, the data is stored in 8-bit format. If this bit is 1, the 16-bit format is used (higher resolution). With 16-bit for- mat, the most significant byte is stored at the lower address. Bit 0: Enable Temperature Logging (ETL). To set up the device for a temperature-logging mission, this bit must be set to logic 1. The recorded temperature val- ues start at address 1000h. Mission Control Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0213h 1 1 SUTA RO (X) TLFS 0 ETL Note: During a mission, there is only read access to this register. Bits 6 and 7 have no function. They always read 1 and cannot be written to 0. Bits 1 and 3 control functions that are not available with the DS1922L/DS1922T. Bit 1 must be set to 0. Under this condi- tion the setting of bit 3 becomes a “don’t care.”
Temperature Logger iButton with 8KB Data-Log Memory Alarm Status The fastest way to determine whether a programmed temperature threshold was exceeded during a mission is by reading the Alarm Status register. In a networked environment that contains multiple DS1922L/ DS1922T i Buttons, the devices that encountered an alarm can quickly be identified by means of the Conditional Search command (see the 1-Wire ROM Function Commands section). The temperature alarm only occurs if enabled (see the Temperature Sensor Alarm section). The BOR alarm is always enabled. Bit 7: Battery-On Reset Alarm (BOR). If this bit reads 1, the device has performed a power-on reset. This indicates that the device has experienced a shock big enough to interrupt the internal battery power supply. The device can still appear functional, but it has lost its factory calibration. Any data found in the data-log mem- ory should be disregarded. Bit 1: Temperature High Alarm Flag (THF). If this bit reads 1, there was at least one temperature conversion during a mission revealing a temperature equal to or higher than the value in the Temperature High Alarm register. A forced conversion can affect the THF bit. This bit can also be set with the initial alarm in the SUTA = 1 mode. Bit 0: Temperature Low Alarm Flag (TLF). If this bit reads 1, there was at least one temperature conversion during a mission revealing a temperature equal to or lower than the value in the Temperature Low Alarm reg- ister. A forced conversion can affect the TLF bit. This bit can also be set with the initial alarm in the SUTA = 1 mode. General Status The information in the General Status register tells the host computer whether a mission-related command was executed successfully. Individual status bits indi- cate whether the DS1922L/DS1922T are performing a mission, waiting for a temperature alarm to trigger the logging of data, or whether the data from the latest mis- sion has been cleared. Bit 4: Waiting for Temperature Alarm (WFTA). If this bit reads 1, the Mission Start Upon Temperature Alarm was selected and the Start Mission command was suc- cessfully executed, but the device has not yet experi- enced the temperature alarm. This bit is cleared after a temperature alarm event, but is not affected by the Clear Memory command. Once set, WFTA remains set if a mission is stopped before a temperature alarm occurs. To clear WFTA manually before starting a new mission, set the high temperature alarm (address 0209h) to -40°C and perform a forced conversion. Bit 3: Memory Cleared (MEMCLR). If this bit reads 1, the Mission Timestamp, Mission Samples Counter, and all the alarm flags of the Alarm Status register have been cleared in preparation of a new mission. Executing the Clear Memory command clears these memory sections. The MEMCLR bit returns to 0 as soon as a new mission is started by using the Start Mission command. The memory must be cleared for a mission to start. Bit 1: Mission in Progress (MIP). If this bit reads 1, the device has been set up for a mission and this mission is still in progress. The MIP bit returns from logic 1 to logic 0 when a mission is ended. See the Start Mission with Password and Stop Mission with Password sections. Alarm Status Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0214h BOR 1 1 1 0 0 THF TLF General Status Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0215h 1 1 0 WFTA MEMCLR 0 MIP 0 Note: There is only read access to this register. Bits 4 to 6 have no function. They always read 1. Bits 2 and 3 have no function with the DS1922L/DS1922T. They always read 0. The alarm status bits are cleared simultaneously when the Clear Memory Function is invoked. See the Memory and Control Function Commands section for details. Note: There is only read access to this register. Bits 0, 2, 5, 6, and 7 have no function.
Temperature Logger iButton with 8KB Data-Log Memory Mission Start Delay The content of the Mission Start Delay Counter register tells how many minutes must expire from the time a mission was started until the first measurement of the mission takes place (SUTA = 0) or until the device starts testing the temperature for a temperature alarm (SUTA = 1). The Mission Start Delay is stored as an unsigned 24-bit integer number. The maximum delay is 16,777,215min, equivalent to 11,650 days or roughly 31 years. If the start delay is nonzero and the SUTA bit is set to 1, first the delay must expire before the device starts testing for temperature alarms to begin logging data. For a typical mission, the Mission Start Delay is 0. If a mission is too long for a single DS1922L/DS1922T to store all readings at the selected sample rate, one can use several devices and set the Mission Start Delay for the second device to start recording as soon as the memory of the first device is full, and so on. The RO bit in the Mission Control register (address 0213h) must be set to 0 to prevent overwriting of collected data once the data-log memory is full. Mission Timestamp The Mission Timestamp register indicates the date and time of the first temperature sample of the mission. There is only read access to the Mission Timestamp register. Mission Progress Indicator Depending on settings in the Mission Control register (address 0213h), the DS1922L/DS1922T log tempera- ture in 8-bit or 16-bit format. The Mission Samples Counter together with the starting address and the log- ging format (8 or 16 bits) provide the information to iden- tify valid blocks of data that have been gathered during the current (MIP = 1) or latest mission (MIP = 0). See the Data-Log Memory Usage section for an illustration. The number read from the Mission Samples Counter indicates how often the DS1922L/DS1922T woke up during a mission to measure temperature. The number format is 24-bit unsigned integer. The Mission Samples Counter is reset through the Clear Memory command. Mission Start Delay Counter Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0216h Delay Low Byte 0217h Delay Center Byte 0218h Delay High Byte Mission Samples Counter Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0220h Low Byte 0221h Center Byte 0222h High Byte Mission Timestamp Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0219h 0 10 Seconds Single Seconds 021Ah 0 10 Minutes Single Minutes 021Bh 0 12/24 20 Hours AM/PM 10 Hours Single Hours 021Ch 0 0 10 Date Single Date 021Dh CENT 0 0 10 Months Single Months 021Eh 10 Years Single Years Note: During a mission, there is only read access to this register. Note: There is only read access to this register. Note: There is only read access to this register.
Temperature Logger iButton with 8KB Data-Log Memory Other Indicators The Device Samples Counter register is similar to the Mission Samples Counter register. During a mission this counter increments whenever the DS1922L/DS1922T wake up to measure and log data and when these devices are testing for a temperature alarm in SUTA mode. Between missions, the counter increments when- ever the Forced Conversion command is executed. This way the Device Samples Counter register functions like a gas gauge for the battery that powers the i Button. The Device Samples Counter register is reset to zero when the i Button is assembled. The number format is 24-bit unsigned integer. The maximum number that can be represented in this format is 16,777,215. Due to the calibration and tests at the factory, new devices can have a count value of up to 35,000. The typical value is well below 10,000. The code in the Device Configuration register allows the master to distinguish between the DS2422 chip and different versions of the DS1922 i Buttons. The Device Configuration Register Bitmap shows the codes assigned to the various devices. Security by Password The DS1922L/DS1922T are designed to use two pass- words that control read access and full access. Reading from or writing to the scratchpad as well as the Forced Conversion command does not require a pass- word. The password must be transmitted immediately after the command code of the memory or control func- tion. If password checking is enabled, the password transmitted is compared to the passwords stored in the device. The data pattern stored in the Password Control register determines whether password checking is enabled. To enable password checking, the EPW bits need to form a binary pattern of 10101010 (AAh). The default pattern of EPW is different from AAh. If the EPW pattern is different from AAh, any pattern is accepted as long as it has a length of exactly 64 bits. Once enabled, changing the passwords and disabling password checking requires the knowledge of the current full- access password. Device Samples Counter Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0223h Low Byte 0224h Center Byte 0225h High Byte Password Control Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0227h EPW Device Configuration Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 PART 0 0 0 0 0 0 0 0 DS2422 0 0 1 0 0 0 0 0 DS1923 0 1 0 0 0 0 0 0 DS1922L 0 1 1 0 0 0 0 0 DS1922T 0226h 1 0 0 0 0 0 0 0 DS1922E Note: There is only read access to this register. Note: There is only read access to this register. Note: During a mission, there is only read access to this register.
Temperature Logger iButton with 8KB Data-Log Memory Before enabling password checking, passwords for read-only access as well as for full access (read/write/control) must be written to the password registers. Setting up a password or enabling/dis- abling the password checking is done in the same way as writing data to a memory location; only the address is different. Since they are located in the same memory page, both passwords can be rede- fined at the same time. The Read Access Password must be transmitted exact- ly in the sequence RP0, RP1…RP62, RP63. This pass- word only applies to the Read Memory with CRC function. The DS1922L/DS1922T deliver the requested data only if the password transmitted by the master was correct or if password checking is not enabled. The full-access password must be transmitted exactly in the sequence FP0, FP1…FP62, FP63. It affects the functions Read Memory with CRC, Copy Scratchpad, Clear Memory, Start Mission, and Stop Mission. The DS1922L/DS1922T execute the command only if the password transmitted by the master was correct or if password checking is not enabled. Due to the special behavior of the write-access logic, the Password Control register and both passwords must be written at the same time. When setting up new passwords, always verify (read back) the scratchpad before sending the Copy Scratchpad command. After a new password is successfully copied from the scratch- pad to its memory location, erase the scratchpad by fill- ing it with new data (Write Scratchpad command). Otherwise, a copy of the passwords remains in the scratchpad for public read access. Read Access Password Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0228h RP7 RP6 RP5 RP4 RP3 RP2 RP1 RP0 0229h RP15 RP14 RP13 RP12 RP11 RP10 RP9 RP8 … … 022Eh RP55 RP54 RP53 RP52 RP51 RP50 RP49 RP48 022Fh RP63 RP62 RP61 RP60 RP59 RP58 RP57 RP56 Full Access Password Register Bitmap ADDRESS BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 0230h FP7 FP6 FP5 FP4 FP3 FP2 FP1 FP0 0231h FP15 FP14 FP13 FP12 FP11 FP10 FP9 FP8 … … 0236h FP55 FP54 FP53 FP52 FP51 FP50 FP49 FP48 0237h FP63 FP62 FP61 FP60 FP59 FP58 FP57 FP56 Note: There is only write access to this register. Attempting to read the password reports all zeros. The password cannot be changed while a mission is in progress. Note: There is only write access to this register. Attempting to read the password reports all zeros. The password cannot be changed while a mission is in progress.
time points of all values stored in the data-log memory. cedure is called missioning. (equivalent to 0168h at EHSS = 1). Figure 7. Temperature Logging
value in the Sample Rate register and the EHSS bit. logged when the temperature alarm occurred. Figure 8. Address Registers
Temperature Logger iButton with 8KB Data-Log Memory corresponding ending offset in this example is 1Fh. For best economy of speed and efficiency, the target address for writing should point to the beginning of a page, i.e., the byte offset is 0. Thus, the full 32-byte capacity of the scratchpad is available, resulting also in the ending offset of 1Fh. The ending offset together with the PF flag are a means to support the master checking the data integrity after a Write command. The highest valued bit of the E/S register, called authorization accepted (AA), indicates that a valid Copy command for the scratchpad has been received and executed. Writing data to the scratchpad clears this flag. Writing with Verification To write data to the DS1922L/DS1922T, the scratchpad must be used as intermediate storage. First, the master issues the Write Scratchpad command to specify the desired target address, followed by the data to be writ- ten to the scratchpad. In the next step, the master sends the Read Scratchpad command to read the scratchpad and to verify data integrity. As preamble to the scratchpad data, the DS1922L/DS1922T send the requested target address TA1 and TA2 and the con- tents of the E/S register. If the PF flag is set, data did not arrive correctly in the scratchpad. The master does not need to continue reading; it can start a new trial to write data to the scratchpad. Similarly, a set AA flag indicates that the Write command was not recognized by the device. If everything went correctly, both flags are cleared and the ending offset indicates the address of the last byte written to the scratchpad. Now the mas- ter can continue verifying every data bit. After the mas- ter has verified the data, it must send the Copy Scratchpad command. This command must be fol- lowed exactly by the data of the three address registers TA1, TA2, and E/S, as the master has read them verify- ing the scratchpad. As soon as the DS1922L/DS1922T have received these bytes, they copy the data to the requested location beginning at the target address. Memory and Control Function Commands Figure 9 shows the protocols necessary for accessing the memory and the special function registers of the DS1922L/DS1922T. An example on how to use these and other functions to set up the DS1922L/DS1922T for a mission is included in the Mission Example: Prepare and Start a New Mission section. The communication between the master and the DS1922L/DS1922T takes place either at standard speed (default, OD = 0) or at overdrive speed (OD = 1). If not explicitly set into the overdrive mode the DS1922L/DS1922T assume stan- dard speed. Internal memory access during a mission has priority over external access through the 1-Wire interface. This affects several commands in this sec- tion. See the Memory Access Conflicts section for details and solutions. Write Scratchpad [0Fh] After issuing the Write Scratchpad command, the mas- ter must first provide the 2-byte target address, fol- lowed by the data to be written to the scratchpad. The data is written to the scratchpad starting at the byte off- set T[4:0]. The master must send as many bytes as are needed to reach the ending offset of 1Fh. If a data byte is incomplete, its content is ignored and the partial byte flag PF is set. When executing the Write Scratchpad command, the CRC generator inside the DS1922L/DS1922T calculates a CRC of the entire data stream, starting at the com- mand code and ending at the last data byte sent by the master (Figure 15). This CRC is generated using the CRC-16 polynomial by first clearing the CRC generator and then shifting in the command code (0Fh) of the Write Scratchpad command, the target addresses TA1 and TA2 as supplied by the master, and all the data bytes. If the ending offset is 11111b, the master can send 16 read time slots and receive the inverted CRC- 16 generated by the DS1922L/DS1922T. Note that both register pages are write protected dur- ing a mission. Although the Write Scratchpad command works normally at any time, the subsequent copy scratchpad to a register page fails during a mission.
Figure 8. The master can continue reading data until DS1922L/DS1922T until a reset pulse is issued. successful. The AA bit remaining at 0 indicates this. 2-byte address that indicates a starting byte location. based on the data as it was transmitted.
Temperature Logger iButton with 8KB Data-Log Memory MASTER Tx MEMORY OR CONTROL FUNCTION COMMAND MASTER Tx TA1 [T7:T0] MASTER Tx DATA BYTE TO SCRATCHPAD OFFSET DS1922 INCREMENTS SCRATCHPAD OFFSET DS1922 SETS SCRATCHPAD OFFSET = [T4:T0] AND CLEARS (PF, AA) 0Fh WRITE SCRATCHPAD? N Y Y N Y N N Y N MASTER Tx RESET? SCRATCHPAD OFFSET = 11111b? MASTER Tx RESET? MASTER Tx RESET? MASTER Tx TA2 [T15:T8] DS1922 SETS [E4:E0] = SCRATCHPAD OFFSET N FROM ROM FUNCTIONS FLOWCHART (FIGURE 11) TO ROM FUNCTIONS FLOWCHART (FIGURE 11) Y Y TO FIGURE 9b FROM FIGURE 9b MASTER Rx CRC-16 OF COMMAND, ADDRESS DATA MASTER Rx "1"s PARTIAL BYTE WRITTEN? PF = 1 AA = 1 MASTER Rx TA1 [T7:T0] DS1922 SETS SCRATCHPAD OFFSET = [T4:T0] DS1922 INCREMENTS SCRATCHPAD OFFSET MASTER Rx ENDING OFFSET WITH DATA STATUS (E/S) AAh READ SCRATCHPAD? N Y Y N Y N Y N MASTER Tx RESET? SCRATCHPAD OFFSET = 11111b? MASTER Tx RESET? MASTER Rx TA2 [T15:T8] MASTER Rx DATA BYTE FROM SCRATCHPAD OFFSET MASTER Rx CRC-16 OF COMMAND, ADDRESS DATA, E/S BYTE, AND DATA STARTING AT THE TARGET ADDRESS MASTER Rx "1"s 99h COPY SCRATCHPAD [WITH PW] N Y Y N N MASTER Tx RESET? MASTER Tx RESET? COPYING FINISHED MASTER Tx E/S BYTE MASTER Tx TA1 [T7:T0], TA2 [T15:T8] AUTHORIZATION CODE MASTER Tx
64 BITS [PASSWORD]
N Y AUTHORIZATION CODE MATCH? N Y N Y Y N MASTER Tx RESET? Y PASSWORD ACCEPTED? DS1922 Tx "0" DS1922 Tx "1" MASTER Rx "1"s MASTER Rx "1"s Figure 9a. Memory/Control Function Flowchart
Temperature Logger iButton with 8KB Data-Log Memory FROM FIGURE 9a TO FIGURE 9a TO FIGURE 9c FROM FIGURE 9c 69h READ MEMORY [WITH PW] AND CRC N N Y Y N N END OF MEMORY? MASTER Tx RESET? CRC OK? MASTER Tx TA1 [T7:T0], TA2 [T15:T8] DS1922 SETS MEMORY ADDRESS = [T15:T0] MASTER Rx DATA BYTE FROM MEMORY ADDRESS Y N N N END OF PAGE? DECISION MADE BY MASTER DECISION MADE BY DS1922 Y N Y Y MASTER Tx RESET? Y PASSWORD ACCEPTED? MASTER Tx RESET MASTER Rx "1"s MASTER Rx CRC-16 OF COMMAND, ADDRESS, DATA (1ST PASS); CRC-16 OF DATA (SUBSEQUENT PASSES) DS1922 INCREMENTS ADDRESS COUNTER N Y MASTER Tx FFh DUMMY BYTE MASTER Tx MEMCLR = 1 YMISSION IN PROGRESS? N N Y MASTER Tx RESET? Y PASSWORD ACCEPTED? DS1922 CLEARS MISSION TIMESTAMP, MISSION SAMPLES COUNTER, ALARM FLAGS 96h CLEAR MEMORY [WITH PW] N N Y MASTER Tx FFh DUMMY BYTE DS1922 COPIES RESULT TO ADDRESS 020C/Dh DS1922 PERFORMS A TEMPERATURE CONVERSION YMISSION IN PROGRESS? N MASTER Tx RESET? Y 55h FORCED CONVERSION? Figure 9b. Memory/Control Function Flowchart (continued)
Temperature Logger iButton with 8KB Data-Log Memory MISSION START DELAY PROCESS FROM FIGURE 9b TO FIGURE 9b YSTART DELAY COUNTER = 0? N NSUTA = 1? Y NTEMPERATURE ALARM? Y MIP = 0? N N N Y MASTER Tx FFh DUMMY BYTE MASTER Tx DS1922 SETS WFTA = 1 DS1922 SETS WFTA = 0 DS1922 DECREMENTS START DELAY COUNTER DS1922 WAITS ONE SAMPLE PERIOD DS1922 PERFORMS 8-BIT TEMPERATURE CONVERSION DS1922 WAITS ONE SAMPLE PERIOD MISSION IN PROGRESS? N Y MASTER Tx RESET? Y PASSWORD ACCEPTED? N Y Y MEMCLR = 1? Y N DS1922 SETS MIP = 1, MEMCLR = 0 DS1922 COPIES RTC DATA TO MISSION TIMESTAMP REGISTER DS1922 STARTS LOGGING TAKING FIRST SAMPLE DS1922 INITIATES MISSION START DELAY PROCESS CCh START MISSION [WITH PW] N Y MASTER Tx FFh DUMMY BYTE MASTER Tx PROGRESS? Y Y MASTER Tx RESET? Y PASSWORD ACCEPTED? DS1922 SETS MIP = 0, WFTA = 0 33h STOP MISSION [WITH PW] N N N END OF PROCESS Figure 9c. Memory/Control Function Flowchart (continued)
Temperature Logger iButton with 8KB Data-Log Memory Clear Memory with Password [96h] The Clear Memory with Password command is used to prepare the device for another mission. This command is only executed if no mission is in progress. After the command code the master must transmit the 64-bit full- access password followed by an FFh dummy byte. If passwords are enabled and the transmitted password is different from the stored full-access password or a mission is in progress, the Clear Memory with Password command fails. The device stops communicating and waits for a reset pulse. If the password was correct or if passwords were not enabled, the device clears the Mission Timestamp register, Mission Samples Counter register, and all alarm flags of the Alarm Status register. After these cells are cleared, the MEMCLR bit of the General Status register reads 1 to indicate the success- ful execution of the Clear Memory with Password com- mand. Clearing of the data-log memory is not necessary because the Mission Samples Counter indi- cates how many entries in the data-log memory are valid. Forced Conversion [55h] The Forced Conversion command can be used to mea- sure the temperature without starting a mission. After the command code, the master must send one FFh byte to get the conversion started. The conversion result is found as a 16-bit value in the Latest Temperature Conversion Result register. This command is only executed if no mission is in progress (MIP = 0). It cannot be interrupted and takes maximum 600ms to complete. During this time memory access through the 1-Wire interface is blocked. The device behaves the same way as during a mission when the sampling inter- feres with a memory/control function command. See the Memory Access Conflicts section for details. Start Mission with Password [CCh] The DS1922L/DS1922T use a control function com- mand to start a mission. A new mission can only be started if the previous mission has been ended and the memory has been cleared. After the command code, the master must transmit the 64-bit full-access pass- word followed by an FFh dummy byte. If passwords are enabled and the transmitted password is different from the stored full-access password or a mission is in progress, the Start Mission with Password command fails. The device stops communicating and waits for a reset pulse. If the password was correct or if pass- words were not enabled, the device starts a mission. If SUTA = 0, the sampling begins as soon as the Mission Start Delay is over. If SUTA = 1, the first sample is writ- ten to the data-log memory at the time the temperature alarm occurred. However, the Mission Samples Counter does not increment. One sample period later, the Mission Timestamp register is set and the regular sam- pling and logging begins. While the device is waiting for a temperature alarm to occur, the WFTA flag in the General Status register reads 1. During a mission there is only read access to the register pages. Stop Mission with Password [33h] The DS1922L/DS1922T use a control function com- mand to stop a mission. Only a mission that is in progress can be stopped. After the command code, the master must transmit the 64-bit full-access pass- word followed by a FFh dummy byte. If passwords are enabled and the transmitted password is different from the stored full-access password or a mission is not in progress, the Stop Mission with Password command fails. The device stops communicating and waits for a reset pulse. If the password was correct or if pass- words were not enabled, the device clears the MIP bit in the General Status register and restores write access to the register pages. The WFTA bit is not cleared. See the description of the General Status register for a method to clear the WFTA bit.
odically a temperature sample is taken and logged. to detect this interference, and how to work around it. and to take measures to work around it. Table 3. Memory Access Conflicts and Solutions CRC-16 at the end of the command flow. the command flow, despite a valid password. the CRC-16 at the end of the memory page. FFh or the MIP bit is 1 while bits 0, 2, and 5 are 0. is 0, Stop Mission was successful.
lent to that shown in Figure 10. pullup resistor of maximum 2.2k Ω at any speed. adapters that are based on these driver chips.
- Initialization
- ROM Function Command
- Memory/Control Function Command
- Transaction/Data Rx RPUP IL VPUP BUS MASTER OPEN-DRAIN PORT PIN 100Ω MOSFET Tx Rx Tx DATA DS1922L/DS1922T 1-Wire PORT Rx = RECEIVE Tx = TRANSMIT
Figure 10. Hardware Configuration
Temperature Logger iButton with 8KB Data-Log Memory Initialization All transactions on the 1-Wire bus begin with an initializa- tion sequence. The initialization sequence consists of a reset pulse transmitted by the bus master followed by presence pulse(s) transmitted by the slave(s). The pres- ence pulse lets the bus master know that the DS1922L/DS1922T are on the bus and are ready to oper- ate. For more details, see the 1-Wire Signalingsection. 1-Wire ROM Function Commands Once the bus master has detected a presence, it can issue one of the eight ROM function commands that DS1922L/DS1922T support. All ROM function com- mands are 8 bits long. A list of these commands follows (see the flowchart in Figure 11). Read ROM [33h] This command allows the bus master to read the DS1922L/DS1922T’s 8-bit family code, unique 48-bit serial number, and 8-bit CRC. This command can only be used if there is a single slave on the bus. If more than one slave is present on the bus, a data collision occurs when all slaves try to transmit at the same time (open drain produces a wired-AND result). The resul- tant family code and 48-bit serial number results in a mismatch of the CRC. Match ROM [55h] The Match ROM command, followed by a 64-bit ROM sequence, allows the bus master to address a specific DS1922L/DS1922T on a multidrop bus. Only the DS1922L/DS1922T that exactly matches the 64-bit ROM sequence responds to the following memory func- tion command. All other slaves wait for a reset pulse. This command can be used with a single device or multiple devices on the bus. Search ROM [F0h] When a system is initially brought up, the bus master might not know the number of devices on the 1-Wire bus or their registration numbers. By taking advantage of the wired-AND property of the bus, the master can use a process of elimination to identify the registration numbers of all slave devices. For each bit of the regis- tration number, starting with the least significant bit, the bus master issues a triplet of time slots. On the first slot, each slave device participating in the search outputs the true value of its registration number bit. On the sec- ond slot, each slave device participating in the search outputs the complemented value of its registration num- ber bit. On the third slot, the master writes the true value of the bit to be selected. All slave devices that do not match the bit written by the master stop participat- ing in the search. If both of the read bits are zero, the master knows that slave devices exist with both states of the bit. By choosing which state to write, the bus master branches in the ROM code tree. After one com- plete pass, the bus master knows the registration num- ber of a single device. Additional passes identify the registration numbers of the remaining devices. Refer to Application Note 187: 1-Wire Search Algorithm for a detailed discussion, including an example. Conditional Search ROM [ECh] The Conditional Search ROM command operates simi- larly to the Search ROM command except that only those devices that fulfill certain conditions participate in the search. This function provides an efficient means for the bus master to identify devices on a multidrop system that have to signal an important event. After each pass of the conditional search that successfully determined the 64-bit ROM code for a specific device on the multidrop bus, that particular device can be indi- vidually accessed as if a Match ROM had been issued, since all other devices have dropped out of the search process and are waiting for a reset pulse. The DS1922L/DS1922T respond to the conditional search ROM command if one of the three alarm flags of the Alarm Status register (address 0214h) reads 1. The temperature alarm only occurs if enabled (see the Temperature Sensor Alarm section). The BOR alarm is always enabled. The first alarm that occurs makes the device respond to the Conditional Search ROM command.
Temperature Logger iButton with 8KB Data-Log Memory Skip ROM [CCh] This command can save time in a single-drop bus sys- tem by allowing the bus master to access the memory functions without providing the 64-bit ROM code. For example, if more than one slave is present on the bus and a read command is issued following the Skip ROM command, data collision occurs on the bus as multiple slaves transmit simultaneously (open-drain pulldowns produce a wired-AND result). Resume [A5h] The DS1922L/DS1922T must be accessed several times before a mission starts. In a multidrop environment this means that the 64-bit ROM code after a Match ROM command must be repeated for every access. To maxi- mize the data throughput in a multidrop environment, the Resume command was implemented. This com- mand checks the status of the RC bit and, if it is set, directly transfers control to the memory/control func- tions, similar to a Skip ROM command. The only way to set the RC bit is through successfully executing the Match ROM, Search ROM, or Overdrive-Match ROM command. Once the RC bit is set, the device can repeatedly be accessed through the Resume command function. Accessing another device on the bus clears the RC bit, preventing two or more devices from simulta- neously responding to the Resume command. Overdrive-Skip ROM [3Ch] On a single-drop bus this command can save time by allowing the bus master to access the memory/control functions without providing the 64-bit ROM code. Unlike the normal Skip ROM command, the Overdrive-Skip ROM command sets the DS1922L/DS1922T in the over- drive mode (OD = 1). All communication following this command must occur at overdrive speed until a reset pulse of minimum 690µs duration resets all devices on the bus to standard speed (OD = 0). When issued on a multidrop bus, this command sets all overdrive-supporting devices into overdrive mode. To subsequently address a specific overdrive-supporting device, a reset pulse at overdrive speed must be issued followed by a Match ROM or Search ROM com- mand sequence. This speeds up the time for the search process. If more than one slave supporting overdrive is present on the bus and the Overdrive-Skip ROM command is followed by a read command, data collision occurs on the bus as multiple slaves transmit simultaneously (open-drain pulldowns produce a wired- AND result). Overdrive-Match ROM [69h] The Overdrive-Match ROM command followed by a 64-bit ROM sequence transmitted at overdrive speed allows the bus master to address a specific DS1922L/ DS1922T on a multidrop bus and to simultaneously set it in overdrive mode. Only the DS1922L/DS1922T that exactly matches the 64-bit ROM sequence respond to the subsequent memory/control function command. Slaves already in overdrive mode from a previous Overdrive-Skip ROM or successful Overdrive-Match ROM command remain in overdrive mode. All over- drive-capable slaves return to standard speed at the next reset pulse of minimum 690µs duration. The Overdrive-Match ROM command can be used with a single or multiple devices on the bus.
Temperature Logger iButton with 8KB Data-Log Memory DS1922 Tx PRESENCE PULSE BUS MASTER Tx RESET PULSE BUS MASTER Tx ROM FUNCTION COMMAND DS1922 Tx CRC BYTE DS1922 Tx FAMILY CODE (1 BYTE) DS1922 Tx SERIAL NUMBER (6 BYTES) OD = 0 RC = 0 MASTER Tx BIT 0 RC = 0 RC = 0 RC = 0 Y OD RESET PULSE? YY Y Y Y Y N 33h READ ROM COMMAND? N 55h MATCH ROM COMMAND? BIT 0 MATCH? BIT 0 MATCH? N N N N N N N F0h SEARCH ROM COMMAND? N ECh CONDITIONAL SEARCH COMMAND? N Y RC = 1 MASTER Tx BIT 1 MASTER Tx BIT 63 BIT 1 MATCH? BIT 63 MATCH? Y Y RC = 1 FROM MEMORY/CONTROL FUNCTION FLOWCHART (FIGURE 9) DS1922 Tx BIT 0 DS1922 Tx BIT 0 MASTER Tx BIT 0 BIT 1 MATCH? BIT 63 MATCH? DS1922 Tx BIT 1 DS1922 Tx BIT 1 MASTER Tx BIT 1 DS1922 Tx BIT 63 DS1922 Tx BIT 63 MASTER Tx BIT 63 Y BIT 0 MATCH?N N N Y Y RC = 1 DS1922 Tx BIT 0 DS1922 Tx BIT 0 MASTER Tx BIT 0 CONDITION MET? N Y BIT 1 MATCH? BIT 63 MATCH? DS1922 Tx BIT 1 DS1922 Tx BIT 1 MASTER Tx BIT 1 DS1922 Tx BIT 63 DS1922 Tx BIT 63 MASTER Tx BIT 63 Y FROM FIGURE 11b TO FIGURE 11b TO FIGURE 11b FROM FIGURE 11b TO MEMORY/CONTROL FUNCTION FLOWCHART (FIGURE 9) Figure 11a. ROM Functions Flowchart
Temperature Logger iButton with 8KB Data-Log Memory MASTER Tx BIT 0 RC = 0; OD = 1 RC = 0; OD = 1 OD = 0 (SEE NOTE) NOTE: THE OD FLAG REMAINS AT 1 IF THE DEVICE WAS ALREADY AT OVERDRIVE SPEED BEFORE THE OVERDRIVE-MATCH ROM COMMAND WAS ISSUED. (SEE NOTE) (SEE NOTE) RC = 1? Y N Y A5h RESUME COMMAND? N Y 3Ch OVERDRIVE- SKIP ROM? N RC = 0 Y CCh SKIP ROM COMMAND? Y 69h OVERDRIVE- MATCH ROM? N N OD = 0N OD = 0N MASTER Tx BIT 1 MASTER Tx BIT 63 Y Y RC = 1 Y BIT 0 MATCH? MASTER Tx RESET? BIT 63 MATCH? BIT 1 MATCH? N Y N YMASTER Tx RESET? N TO FIGURE 11a FROM FIGURE 11a FROM FIGURE 11a TO FIGURE 11a Figure 11b. ROM Functions Flowchart (continued)
Temperature Logger iButton with 8KB Data-Log Memory Master-to-Slave For a write-one time slot, the voltage on the data line must have crossed the VTH threshold before the write-one low time tW1LMAX is expired. For a write-zero time slot, the voltage on the data line must stay below the V TH threshold until the write-zero low time tW0LMIN is expired. The voltage on the data line should not exceed V ILMAX during the entire t W0L or t W1L window. After the V TH threshold has been crossed, the DS1922L/DS1922T need a recovery time t REC before they are ready for the next time slot. Slave-to-Master A read-data time slot begins like a write-one time slot. The voltage on the data line must remain below V TL until the read low time t RL is expired. During the t RL window, when responding with a 0, the DS1922L/ DS1922T start pulling the data line low; their internal timing generator determines when this pulldown ends and the voltage starts rising again. When responding with a 1, the DS1922L/DS1922T do not hold the data line low at all, and the voltage starts rising as soon as t RL is over. The sum of tRL + δ (rise time) on one side and the inter- nal timing generator of the DS1922L/DS1922T on the other side define the master sampling window (t MSRMIN to tMSRMAX) in which the master must perform a read from the data line. For most reliable communication, t RL should be as short as permissible and the master should read close to but no later than t MSRMAX. After reading from the data line, the master must wait until t SLOT is expired. This guarantees sufficient recovery time tREC for the DS1922L/DS1922T to get ready for the next time slot. Improved Network Behavior (Switchpoint Hysteresis) In a 1-Wire environment line termination is possible only during transients controlled by the bus master (1-Wire driver). 1-Wire networks, therefore, are suscep- tible to noise of various origins. Depending on the physical size and topology of the network, reflections from end points and branch points can add up or can- cel each other to some extent. Such reflections are vis- ible as glitches or ringing on the 1-Wire communication line. Noise coupled onto the 1-Wire line from external sources can also result in signal glitching. A glitch dur- ing the rising edge of a time slot can cause a slave device to lose synchronization with the master and, as a consequence, result in a search ROM command coming to a dead end or cause a device-specific func- tion command to abort. For better performance in net- work applications, the DS1922L/DS1922T use a new 1-Wire front-end, which makes them less sensitive to noise and also reduces the magnitude of noise inject- ed by the slave device itself. The DS1922L/DS1922T’s 1-Wire front-end differs from traditional slave devices in four characteristics: 1) The falling edge of the presence pulse has a con- trolled slew rate. This provides a better match to the line impedance than a digitally switched transistor, converting the high-frequency ringing known from traditional devices into a smoother low-bandwidth transition. The slew-rate control is specified by the parameter t FPD, which has different values for stan- dard and overdrive speed. 2) There is additional lowpass filtering in the circuit that detects the falling edge at the beginning of a time slot. This reduces the sensitivity to high-frequency noise. This additional filtering does not apply at over- drive speed. 3) There is a hysteresis at the low-to-high switching threshold V TH. If a negative glitch crosses V TH but does not go below V TH - V HY, it is not recognized (Figure 14, Case A). The hysteresis is effective at any 1-Wire speed. 4) There is a time window specified by the rising edge hold-off time t REH during which glitches are ignored, even if they extend below V TH - V HY threshold (Figure 14, Case B, t GL < t REH ). Deep voltage droops or glitches that appear late after crossing the V TH threshold and extend beyond the t REH window cannot be filtered out and are taken as the begin- ning of a new time sl ot (Figure 14, Case C, t GL ≥ tREH). Devices that have the parameters t FPD, VHY, and t REH specified in their electrical characteristics use the improved 1-Wire front-end.
Figure 13. Read/Write Timing Diagrams
Temperature Logger iButton with 8KB Data-Log Memory ing in the command code, the target addresses TA1 and TA2, and all the data bytes. The DS1922L/DS1922T transmit this CRC only if the data bytes written to the scratchpad include scratchpad ending offset 11111b. The data can start at any location within the scratchpad. With the Read Scratchpad command, the CRC is gen- erated by first clearing the CRC generator and then shifting in the command code, the target addresses TA1 and TA2, the E/S byte, and the scratchpad data starting at the target address. The DS1922L/DS1922T transmit this CRC only if the reading continues through the end of the scratchpad, regardless of the actual ending offset. For more information on generating CRC values, refer to Application Note 27. Command-Specific 1-Wire Communication Protocol—Legend SYMBOL DESCRIPTION RST 1-Wire reset pulse generated by master. PD 1-Wire presence pulse generated by slave. Select Command and data to satisfy the ROM function protocol. WS Command “Write Scratchpad.” RS Command “Read Scratchpad.” CPS Command “Copy Scratchpad with Password.” RMC Command “Read Memory with Password and CRC.” CM Command “Clear Memory with Password.” FC Command “Forced Conversion.” SM Command “Start Mission with Password.” STP Command “Stop Mission with Password.” TA Target Address TA1, TA2. TA-E/S Target Address TA1, TA2 with E/S byte. <Data to EOS> Transfer of as many data bytes as are needed to reach the scratchpad offset 1Fh. <Data to EOP> Transfer of as many data bytes as are needed to reach the end of a memory page. <Data to EOM> Transfer of as many data bytes as are needed to reach the end of the data-log memory. <PW/Dummy> Transfer of 8 bytes that either represent a valid password or acceptable dummy data. <32 Bytes> Transfer of 32 bytes. <Data> Transfer of an undetermined amount of data. FFh Transmission of one FFh byte. CRC-16 Transfer of an inverted CRC-16. FF Loop Indefinite loop where the master reads FF bytes. AA Loop Indefinite loop where the master reads AA bytes.
Temperature Logger iButton with 8KB Data-Log Memory RST Write Scratchpad, Reaching the End of the Scratchpad (Cannot Fail) PD WS TASelect CRC-16 FF Loop<Data to EOS> CRC-16 FF Loop CRC-16 RST Read Scratchpad (Cannot Fail) PD RS TA-E/SSelect <Data to EOS> AA LoopRST Copy Scratchpad with Password (Success) PD CPS TA-E/SSelect <PW/Dummy> FF Loop FF Loop Loop RST Copy Scratchpad with Password (Fail TA-E/S or Password) PD CPS TA-E/SSelect <PW/Dummy> FF Loop FF Loop RST Read Memory with Password and CRC (Fail Password or Address) PD RMC FFh Select <PW/Dummy> RST TA TA Read Memory with Password and CRC (Success) PD RMCSelect <PW/Dummy> <Data to EOP> RST CM Clear Memory with Password PD Select <PW/Dummy> CRC-16<32 Bytes> To verify success, read the General Status register at address 0215h. If MEMCLR is 1, the command was executed successfully. Command-Specific 1-Wire Communication Protocol—Color Codes Master-to-Slave Slave-to-Master 1-Wire Communication Examples
Temperature Logger iButton with 8KB Data-Log Memory Mission Example: Prepare and Start a New Mission Assumption: The previous mission has been ended by using the Stop Mission command. Passwords are not enabled. The device is a DS1922L. Starting a mission requires three steps: Step 1: Clear the data of the previous mission. Step 2: Write the setup data to register page 1. Step 3: Start the new mission. Step 1: Clear the data of the previous mission. With only a single device connected to the bus master, the communication of step 1 looks like this: RST Forced Conversion PD FCSelect FF LoopFFh To read the result and to verify success, read the addresses 020Ch to 020Fh (results) and the Device Samples Counter at address 0223h to 0225h. If the count has incremented, the command was executed successfully. FF LoopRST Start Mission with Password PD SMSelect <PW/Dummy> FFh To verify success, read the General Status register at address 0215h. If MIP is 1 and MEMCLR is 0, the command was executed successfully. RST Stop Mission with Password PD STPSelect FF Loop<PW/Dummy> FFh To verify success, read the General Status register at address 0215h. If MIP is 0, the command was executed successfully. 1-Wire Communication Examples (continued) MASTER MODE DATA (LSB FIRST) COMMENTS Tx (Reset) Reset pulse Rx (Presence) Presence pulse Tx CCh Issue “Skip ROM” command Tx 96h Issue “Clear Memory” command Tx <8 FFh bytes> Send dummy password Tx FFh Send dummy byte Tx (Reset) Reset pulse Rx (Presence) Presence pulse
Temperature Logger iButton with 8KB Data-Log Memory Step 2: Write the setup data to register page 1. During the setup, the device needs to learn the follow- ing information:
- Time and Date
- Sample Rate
- Alarm Thresholds
- Alarm Controls (Response to Conditional Search)
- General Mission Parameters (e.g., Channels to Log and Logging Format, Rollover, Start Mode)
- Mission Start Delay The following data sets up the DS1922L for a mission that logs temperature using 8-bit format. ADDRESS DATA EXAMPLE VALUES FUNCTION 0200h 00h 0201h 30h 0202h 15h 15:30:00 hours Time 0203h 01h 0204h 04h 0205h 02h 1st of April in 2002 Date 0206h 0Ah 0207h 00h Every 10 minutes (EHSS = 0) Sample rate 0208h 52h 0209h 66h 0°C low 10°C high Temperature Alarm Thresholds 020Ah 00h 020Bh FFh (Don’t care) (Not applicable with DS1922L/DS1922T) 020Ch FFh 020Dh FFh 020Eh FFh 020Fh FFh (Don’t care) Clock through read-only registers 0210h 02h Enable high alarm Temperature Alarm Control 0211h FCh Disabled (Not applicable with DS1922L/DS1922T) 0212h 01h On (enabled), EHSS = 0 (low sample rate) RTC Oscillator Control, sample rate selection 0213h C1h Normal start; no rollover; 8-bit temperature log General Mission Control 0214h FFh 0215h FFh (Don’t care) Clock through read-only registers 0216h 5Ah 0217h 00h 0218h 00h 90 minutes Mission Start Delay
Temperature Logger iButton with 8KB Data-Log Memory With only a single device connected to the bus master, the communication of step 2 looks like this: MASTER MODE DATA (LSB FIRST) COMMENTS Tx (Reset) Reset pulse Rx (Presence) Presence pulse Tx CCh Issue “Skip ROM” command Tx 0Fh Issue “Write Scratchpad” command Tx 00h TA1, beginning offset = 00h Tx 02h TA2, address = 02 00h Tx <25 Data Bytes> Write 25 bytes of data to scratchpad Tx <7 FFh Bytes> Write through the end of the scratchpad Tx (Reset) Reset pulse Rx (Presence) Presence pulse Tx CCh Issue “Skip ROM” command Tx AAh Issue “Read Scratchpad” command Rx 00h Read TA1, beginning offset = 00h Rx 02h Read TA2, address = 02 00h Rx 1Fh Read E/S, ending offset = 1Fh, flags = 0h Rx <32 Data Bytes> Read scratchpad data and verify Tx (Reset) Reset pulse Rx (Presence) Presence pulse Tx CCh Issue “Skip ROM” command Tx 99h Issue “Copy Scratchpad” command Tx 00h TA1 Tx 02h TA2 Tx 1Fh E/S (AUTHORIZATION CODE) Tx <8 FFh Bytes> Send dummy password Tx (Reset) Reset pulse Rx (Presence) Presence pulse MASTER MODE DATA (LSB FIRST) COMMENTS Tx (Reset) Reset pulse Rx (Presence) Presence pulse Tx CCh Issue “Skip ROM” command Tx CCh Issue “Start Mission” command Tx <8 FFh Bytes> Send dummy password Tx FFh Send dummy byte Tx (Reset) Reset pulse Rx (Presence) Presence pulse Step 3: Start the new mission. With only a single device connected to the bus master, the communication of step 3 looks like this: If step 3 was successful, the MIP bit in the General Status register is 1, the MEMCLR bit is 0, and the Mission Start Delay counts down.
Temperature Logger iButton with 8KB Data-Log Memory Software Correction Algorithm for Temperature The accuracy of high-resolution temperature conver- sion results (forced conversion as well as temperature logs) can be improved through a correction algorithm. The data needed for this software correction is stored in the calibration memory (memory page 18, duplicated in page 19). This data consists of reference tempera- ture (T r) and conversion result (Tc) for two different tem- peratures. See the Temperature Conversion section for the binary number format. The software correction algorithm requires two addi- tional values, which are not stored in the device. These values, Tr1 and Offset, are derived from the device configuration byte. The correction algorithm consists of two steps: prepa- ration and execution. By means of the family code the preparation step verifies whether the device actually is a DS1922. Then the configuration byte is checked to identify the type of DS1922 (L or T). If it is the correct device, the data for software correction is read and converted from binary to decimal °C format. Next, three coefficients A, B, and C are computed. In the execution step, the temperature reading as delivered by the DS1922 is first converted from the low- byte/high-byte format (TcL, TcH) to °C (T c) and then corrected to T CORR. Once step 1 is performed, the three coefficients can be used repeatedly to correct any temperature reading and temperature log of the same device. ADDRESS DESIGNATOR DESCRIPTION 0240h Tr2H Cold-reference temperature, high byte 0241h Tr2L Cold-reference temperature, low byte 0242h Tc2H Conversion result at cold-reference temperature, high byte 0243h Tc2L Conversion result at cold-reference temperature, low byte 0244h Tr3H Hot-reference temperature, high byte 0245h Tr3L Hot-reference temperature, low byte 0246h Tc3H Conversion result at hot-reference temperature, high byte 0247h Tc3L Conversion result at hot-reference temperature, low byte Step 1. Preparation Read the 64-bit ROM to obtain the family code. If family code ≠ 41h, then stop (wrong device). Read the configuration byte at address 0226h. If code = 40h, then Tr1 = 60, Offset = 41 (DS1922L) If code = 60h, then Tr1 = 90, Offset = 1 (DS1922T) For all other codes, stop (wrong device). Tr2 = Tr2H/2 + Tr2L/512 - Offset (convert from binary to °C) Tr3 = Tr3H/2 + Tr3L/512 - Offset (convert from binary to °C) Tc2 = Tc2H/2 + Tc2L/512 - Offset (convert from binary to °C) Tc3 = Tc3H/2 + Tc3L/512 - Offset (convert from binary to °C) Err2 = Tc2 - Tr2 Err3 = Tc3 - Tr3 Err1 = Err2 B = (Tr2 2 - Tr12) x (Err3 - Err1)/[(Tr22 - Tr12) x (Tr3 - Tr1) + (Tr32 - Tr12) x (Tr1 - Tr2)] A = B x (Tr1 - Tr2) / (Tr22 - Tr12) C = Err1 - A x Tr12 - B x Tr1 Step 2. Execution T C = TcH/2 + TcL/512 - Offset (convert from binary to °C) TCORR = Tc - (A x Tc2 + B x Tc + C) (the actual correction)
Temperature Logger iButton with 8KB Data-Log Memory Numerical Correction Example CONVERTED DATA FROM CALIBRATION MEMORY ERROR VALUES Tr1 = 60°C — Tr2 = -10.1297°C Err2 = 0.0672°C Tr3 = 24.6483°C Err3 = -0.1483°C Tc2 = -10.0625°C Err1 = 0.0672°C Tc3 = 24.5°C — RESULTING CORRECTION COEFFICIENTS APPLICATION OF CORRECTION COEFFICIENTS TO SAMPLE READING B = -0.008741 — A = 0.000175/°C T C = 22.500°C C = -0.039332°C T CORR= 22.647°C Note: The software correction requires floating-point arithmetic (24 bit or better). Suitable math libraries for microcontrollers are found on various websites and are included in cross compilers. A1 41 000000FBC52B 1-Wire® iBut t o n® . com YYWW ZZZ DS1922L#F50 16.25mm 5.89mm 0.51mm 17.35mm BRANDING F5 SIZE GND IO Thermochron® Pin Configuration Thermochron is a registered trademark of Maxim Integrated Products, Inc.
Package Information
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. F5 iButton IB#6CB 21-0266 —
Temperature Logger iButton with 8KB Data-Log Memory Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circu it patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 52 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
Added bullet “Water resistant or waterproof if placed inside DS9107 i Button capsule (Exceeds Water Resistant 3 ATM requirements)”; deleted “application pending” from UL bullet and safety statement; added text to Application section: Note that the initial sealing level of DS1922L/DS1922T achieves IP56. Aging and use conditions can degrade the integrity of the seal over time, so for applications with significant exposure to liquids, sprays, or other similar environments, it is recommended to place the Thermochron in the DS9107 i Button capsule. The DS9107 provides a watertight enclosure that has been rated to IP68 (See www.maximic.com/AN4126 ) 1, 4, 12 8 4/09 Created newer template-styled data sheet All 9 10/09 Deleted the standard part numbers from the Ordering Information table 1 10 4/11 Updated UL certificate reference; deleted from the tW1L specification in the Electrical Characteristics table; applied note 14 to the t W0L specification in the Electrical Characteristics table; added more details to Electrical Characteristics table notes 5, 14, and 15; revised the last sentence of the Parasite Power section for more clarity; added paragraph on validation certificates to Detailed Description section; added more details on the Device Samples Counter in the Other Indicators section 1, 3, 4, 13, 25