UM1542 STMICROELECTRONICS | Alldatasheet
Document overview
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Technical content
Datasheet sections
- 1 Kit introduction
- 1.1 Package contents
- 1.2 Board presentation
- 2 Functional description
- 2.1 Performance
- 2.2 Ensured functions
- 2.2.1 Temperature control
- 2.2.2 Compressor control
- 2.2.3 Light bulb and buzzer control
- 2.2.4 Defrost resistor and fan control
- 2.3 Hardware features
- 2.3.1 ACS and ACST devices
- 2.3.2 STM8S003 microcontroller
- 2.3.3 Control side and communication side power supplies
- 2.3.4 STM32F103 microcontroller
- 2.4 Graphic user interface (GUI)
- 3 Using the STEVAL-IHT001V2 ther mostat kit
- 3.1 Thermostat versions
- 3.2 Loads power
- 3.3 Measure points
- 3.4 Pulse control
- 3.5 Getting started
- 3.5.1 Jumper configuration for standalone or PC-driven modes
- 3.5.2 Getting started
- 3.5.3 Operating modes
- 3.5.4 Instructions for the GUI software
- 3.6 GUI windows description
- 3.6.1 Temperature control tab
- 3.6.2 Timing control tab
- 3.6.3 Force debug
- 3.6.4 Parameter measurements
cold appliances market to be addressed. capacitor must be chosen for a 30 mA output DC current (see Appendix H). maximum temperature depends on the power of the loads (Section 3.2). Figure 1. STEVAL-IHT001V2 board between the PC and STM8 MCU, only in order to allow communication through the GUI.
1 Kit introduction
1.1 Package contents
- A thermostat board (ref.: STEVAL-IHT001V2)
- An M2020 5k NTC from EPCOS (ref.: M2020/5k/A20)
- A CD-ROM, including product presentations and datasheets, user manual (this document), application notes, firmware and the GUI software.
1.2 Board presentation
Figure 2. All devices dedicated to thermostat control are placed on the left side (control Figure 2. Board details
These two parts consist of (see Appendix B for the schematic):
- Control side: – Capacitive power supply, supplying only the control side of the board. The average output current of the capacitor power supply is about 25 mA with the embedded 1 µF C29 capacitor (for a 230 V-50 Hz line RMS voltage) – STM8S003 microcontroller, low-cost MCU dedicated to thermostat control – AC switches: an ACST610-8FP , an ACS110-7SN and two ACS102-6TA, which control a compressor, a defrost resistor, a light bulb and a fan, respectively – One red ON/OFF LED. This LED turns ON when the board is powered – Five green LEDs for temperature set point visualization – Two push buttons to increase/decrease the temperature set point: Temp+ and Temp- – A buzzer to warn the user if the appliance door has been open for long time – Connectors for the NTC and door switch – One switch to simulate the door switch
- Interface side: – STM32F103 microcontroller to implement USB interface – Opto-insulators to implement safety insulation between the board and the computer to allow communication with the GUI when the board is plugged into the line voltage – DC/DC converter to supply the opto-couplers from the USB supply – Switches for standalone/PC-driven configuration (see Section 3.5.1) – Mini-USB connector The control side is independent from the interface side, i.e. control is ensured by powering on the control side only (in this case no GUI interfacing is allowed, of course). Warning: Safety insulation is implemented between the board and the computer to allow GUI communication when the board is plugged into the line voltage, but the control side of the board is not electrically isolated from the AC input. The STM8 microcontroller is directly linked to the mains voltage. There is no insulation between the accessible parts and the high voltage. The STEVAL-IHT001V2 kit must be used with care and only by persons qualified for working with electricity at mains voltage levels. Any measurement equipment must be isolated from the mains before powering the board. To use an oscilloscope with the kit, it is safer to isolate it from the AC line. This prevents a shock from occurring as a result of touching any single point in the circuit, but does not prevent shocks when touching two or more points in the circuit.
Functional description UM1542 8/43 Doc ID 023172 Rev 1
2 Functional description
2.1 Performance
This board has been developed to fulfill the following requirements:
- Suitability for a wide range of cold appliances: this thermostat board can control the loads traditionally used in low, medium and high-end cold appliances - compressor, light, defrost resistor (if present), fan (if present).
- All AC loads are switched on at mains zero voltage, and operate in full-cycle conduction mode. This allows suppressing any EMI conduction noise.
- Electromagnetic compatibility: the board is able to withstand bursts up to 3.1 kV during IEC61000-4-4 standard tests without any operational problem. Surge tests have also been performed (IEC61000-4-5 standard) with bursts of 2 kV applied without any damage to the semiconductors.
- Compliance to safety standards: a 2 mm gap is ensured between all high-voltage and low-voltage parts (to obtain a functional level of isolation). The thermal sensor (NTC) is a class-2 sensor and can be put on non-earthed accessible and conductive parts. The STEVAL-IHT001V2 kit provides added value in terms of:
- Low-cost solution for spark-free thermostat – No need for a sealed version – Low-cost STM8S microcontroller for thermostat control – Low-cost capacitive power supply
- Efficiency – Fridge consumption lowered by adjusting and reducing the hysteresis threshold of the temperature control (not easy with mechanical thermostats) – Improved efficiency by turning on the defrost resistor only when it's useful and not at each OFF cycle of the compressor (as done in some mechanical thermostats)
- Flexibility – Customization: program setting with PC interface to change firmware variables – Industrialization: end-of-production MCU programming thanks to FLASH, for soft upgrade and efficient MCU stock management
2.2 Ensured functions
2.2.1 Temperature control
For the thermal sensor, an insulated class-2 NTC resistor has been used. The part number is B57020M2502A020 from EPCOS which is commonly used for these applications. The value of this resistor increases when temperature decreases according to an exponential law. In order to linearize this relation, thus allowing an easier measurement, a series resistor has been added (see Appendix A for details). The NTC must be placed on the evaporator of the fridge or the freezer. The controlled evaporator temperature should be in the range: [-40 to 10] °C. Temperature regulation is achieved by hysteresis control (see Figure 3).
Figure 3. Hysteresis law while the hysteresis value can only be changed using the GUI.
Functional description UM1542 10/43 Doc ID 023172 Rev 1
2.2.2 Compressor control
The ACST610-8FP device (referred to as Q1 in Appendix B) is used to turn on and off the compressor according to the evaporator temperature, sensed through the NTC resistor. Enough room around this AC switch has been left available to add a heatsink if needed.
2.2.3 Light bulb and buzzer control
The slider SW2 on the thermostat board has been placed on the board in order to simulate the fridge/freezer door. A light bulb is switched on or off according to the position of the door switch, open or closed respectively. The embedded switch may be replaced by an external switch using connector J15, in which case switch SW2 must be set in the “Open” position. If the fridge door or the door switch remains in the open position more than one minute, the buzzer PZ1 sounds and the LEDs D4, D5, D7, D8, D9 flashes. The buzzer can be stopped by pressing the Temp+ or Temp- button once (the LEDs keeps on flashing while the door is in the open position). In the PC GUI driven mode the buzzer can be stopped with the GUI software (refer to the “Help” menu of the GUI). When the door is open, the temperature order can only be changed using the GUI software. The light bulb is driven by the ACS102-6TA, Q4 on the thermostat board (Appendix B). It should be noted that an R23 resistor has been added in series with Q4. Indeed, as the lamp lifetime ends, the filament breaks. The overall filament can be short-circuited by the flashover, and the load current is no longer limited. This current can exceed the i²t capability of the ACS and destroy it (cf. AN1172). To avoid destroying the ACS102 at each lamp flashover, a power resistor is added in series with the light. This resistor is rated in order to limit the ACS current to its I TSM value (10 A for a 10 ms half sinus conduction). In this case, a 33 Ω 1/2 W resistor is sufficient. These resistor pads could be also used to put an inductor to limit the dI/dt if a CFL/LED lamp is used in dimming mode.
2.2.4 Defrost resistor and fan control
Defrost resistor is controlled only when the thermostat is set to “Defrost” or to “air circulation” versions; while the fan is controlled only in the “air circulation” version. The defrost resistor is driven by the ACS110-7SB2, Q2 on the thermostat board (see Appendix B). This device is turned on following the “Defrost activation delay” parameter time defined in the GUI software. This time is compared to the sum of the compressor ACST ON times. When this sum is higher than the “Defrost activation delay”, defrost resistor ACST is enabled and then switched on as soon as the evaporator temperature is higher than T HIGH_lim (Figure 4). It remains on during the “Defrost duration” time defined in the GUI software. The conduction starts just before the conduction cycle of the compressor in order to reduce power consumption.
Figure 4. Defrost control ACS102-6T, Q3 on the thermostat board (Appendix B). the fan is turned off while the compressor is still running).
2.3 Hardware features
2.3.1 ACS and ACST devices
Table 1. ACS vs. TRIAC devices
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2.3.2 STM8S003 microcontroller
The MCU used in the thermostat kit is the STM8S003F3P6 belonging to the STM8S003 MCU family. It embeds a large number of features at minimum cost. This part number is used in order to minimize the number of pins. This causes some pins to be shared for different function recovery (LED3/SWIM_line, LED4/USART_CTS and LED5/USART_TX, Figure 12). The functions shared are functions dedicated to communication, i.e. no pin sharing in standalone mode. In order to further reduce costs, the internal oscillator has been used in order to generate the clock.
2.3.3 Control side and communi cation side power supplies
A capacitive power supply is used for the control side of the board. A 1 µF capacitor, C29, has been chosen to supply the board - i.e. the control side of the board - with 25 mA, which is the maximum average current sunk by the control board (230 V-50 Hz line RMS voltage). For more information about the design of the capacitive power supply, please refer to the application note AN1476. In order to reduce the surge current, an R25 resistor is used in series with the C29 capacitor. Even if the power dissipation of this resistor is limited to ½ W for a 30 mA output DC average current (for R25 = 47 Ω and 230 V line RMS voltage), a 2 W resistor has to be used on the board to sustain the inrush current. One particularity of STEVAL-ITH001V2 board power supply is that it is “negative”. Indeed, the Vdd terminal is connected to neutral which means that the GND voltage is 5 V below neutral. This type of connection is mandatory to drive ACS devices. Indeed, ACSs can only be triggered by a negative current (i.e. sourced from the gate). The communication side (with the STM32F103 microcontroller), is only supplied by the PC, by means of the USB connector, through the voltage regulator U2 (see Appendix B).
2.3.4 STM32F103 microcontroller
As for the connection between the PC and the STM8 microcontroller, a USB bus is used. Since the low-cost MCU dedicated to thermostat control does not embed a USB interface, a second MCU has been used to work as a gateway between the PC and the STM8. This MCU is an STM32F103C6, belonging to the STM32F103 family. It is only used for demonstrative purposes, i.e. for communication in PC GUI driven mode.
2.4 Graphic user interface (GUI)
The graphical user interface (GUI) was developed in order to allow the user to set some control parameters, to configure the thermostat for the different versions (basic, defrost, air circulation), and to acquire variables during tests. The user can also choose to program the STM8 microcontroller with new control parameters. The connection with the PC, using the USB interface, is ensured by the STM32 MCU embedding a USB peripheral.
UM1542 Functional description Doc ID 023172 Rev 1 13/43 The GUI provides the following features (refer to the “Help” menu of the GUI software for more information):
- Slide bars to change the MCU parameters (refer to Figure 7 and 8): – Temperature hysteresis – Evaporator temperature set point for each thermostat order – Gate current pulse widths and delays – Time before defrost activation and defrost duration – ZVS delay (synchronization of MCU commands with the mains voltage)
- Virtual knob to set the evaporator temperature level
- Virtual switch (“debug active”) to force the loads to on or off states (compressor, light, defrost, fan) for easier board validation
- Measurement and storage of several parameters during operation (duty cycle and running period of the compressor, evaporator temperature evolution, mains frequency and load status). The most recently modified variables with the GUI can be stored for operation in standby mode. It can be noted from Figure 2 that the part of the PCB dedicated to the PC interface is clearly separated from that part of PCB dedicated to thermostat control in order to easily visualize the component count dedicated only to the thermostat application. By means of opto-couplers, safety insulation is implemented between the board and the PC to allow communication with the GUI when the board is plugged into the line voltage. These opto-couplers, U3, U4, and U5 are supplied from the USB connector CN1 and the DC-DC converter J1 in order to not sink current from the capacitive power supply (Appendix B).
Using the STEVAL-IHT001V2 thermostat kit UM1542 14/43 Doc ID 023172 Rev 1
3 Using the STEVAL-IHT001V2 thermostat kit
3.1 Thermostat versions
The target market of the STEVAL-IHT001V2 kit is represented by low-end to high-end cold appliances, thus addressing a wide range of the COLD market. In particular, the MCU firmware is configurable to work in:
- Basic version: compressor and light bulb control
- Defrost version: compressor, light bulb and defrost resistor control
- Air circulation version (default): compressor, light bulb, defrost resistor and fan control When the target thermostat is selected using the GUI, the gates associated with non- operating loads are no longer controlled, and remain uncontrolled even if the GUI is disconnected. To allow again fan or defrost heater control, the user has to re-program the STM8 MCU using the GUI.
3.2 Loads power
There is no heatsink mounted on the package of ACST610-8FP devices. In this case, the maximum permanent allowed current is 1.5 A RMS, for an ambient temperature lower than 40 °C (which is usually the highest operating temperature as the thermostat is either inside the fridge or outside on top, so at room temperature). If the ACST610-8FP must sink a higher current, or works at a higher temperature, a heatsink can be added. If its case temperature is kept below 92 °C, these devices can control a 6 A RMS current (as shown in Fig. 3 of the ACST6 datasheet). Refer to AN533 for further information on thermal management. Refer also to AN1354 for more information on single-phase compressor control. The ACS102-6T, in the TO-92 package, can withstand a 0.2 A RMS permanent current up to an ambient temperature of 100 °C. The ACS102-6T can drive the common light bulbs or fan found in the fridge or freezer without any problem. Indeed, a 25 W bulb always sinks a current lower than 150 mA and ACS102-6T can drive a maximum power fan of 40 W. The ACS110 can drive a maximum 160 W defrost resistor for an ambient temperature lower than 40 °C. Indeed, the ACS110 cooling PCB pad of the thermostat kit demonstration board is cut down to the SOT223 tab size. As shown in fig. 2-2 of the ACS110-7SN datasheet, it can withstand a 1 A RMS permanent current up to an ambient temperature of 60 °C (with a copper surface of 5 cm² under the SOT223 tab) and can then drive a 200 W defrost resistor.
3.3 Measure points
definitions of the measurement points. Figure 5. Placement of test points
3.4 Pulse control
both the mains rising and falling edges to synchronize the gate pulse with the mains voltage.
- T1 is the mains voltage / compressor current phase shift. It helps to apply the gate current pulse just when the Q1 current reaches zero, in order to control the compressor
Table 2. List of test points
- T2 is the gate current pulse width for Q2 (defrost resistor)
- T3 is the gate current pulse width for Q1 (compressor)
- T4 is the mains voltage / fan current phase shift
- T5 is the gate current pulse width for Q3 (fan)
- T6 is the gate current pulse width for Q4 (light bulb)
Figure 6. Timing definition for gate current pulses right control of loads, otherwise the default parameters shown in Table 3 are used. Table 3. Allowable ranges for gate current pulses
3.5 Getting started
3.5.1 Jumper configuration for standalone or PC-driven modes
Default jumper positions are indicated in the silkscreen and in Table 4. insulated power source may result in damage to the PC. note that, once the thermostat board is operating, the operating mode cannot be changed. SW8 and power ON again (Section 3.5.2). Table 4. Jumper default configuration in standalone or PC-driven operating mode
Using the STEVAL-IHT001V2 thermostat kit UM1542 18/43 Doc ID 023172 Rev 1
3.5.2 Getting started
To operate the STEVA-LIHT001V2 board correctly, follow the steps below given for each mode. Standalone mode 1. Connect the NTC thermistor to the “NTC” connector on the thermostat board (control side) 2. Connect the DOOR switch (if an external door switch is going to be used) to the “DOOR SWITCH” connector on the thermostat board (control side), and set the door switch embedded on the board to the open position to allow the external switch to drive the door pin. Otherwise, if no external door switch is used, move the embedded one to the desired position: open or close. Note that when it is set in the open position, no temperature setting is allowed (except by using the GUI software in the PC-GUI driven mode). A closed position is required for temperature setting using the Temp+/Temp- push buttons. 3. Connect the loads on the thermostat board (see Figure 2) – Compressor to “J10” connector – Defrost resistor to “J11” connector – Fan to “J12” connector – Indoor light bulb to “J13” connector. 4. Ensure that jumpers and switches are set as indicated in Table 4 and 5. 5. Plug the mains wire into “MAINS” conne ctor. Plug the mains wire into the mains voltage. 6. After a few seconds, during which the MCU setup operations and frequency measurement operation take place: – The “on/off” red LED turns on – The D7 LED turns on, indicating that medium temperature is set. – The compressor and fan switch on if the sensed temperature is above the temperature order (should be the case if the NTC is at ambient temperature). – The light bulb is switched on if the DOOR switch is in an open position, in which case the fan is switched off. – The LED D8 turns on for about a half second during the setup phase, then it is switched off. Table 5. Operating mode selector
Description
Standalone mode PC-driven mode SW8
UM1542 Using the STEVAL-IHT001V2 thermostat kit Doc ID 023172 Rev 1 19/43 PC GUI driven mode 1. Repeat steps 1 to 3 of “standalone mode” 2. Ensure that the jumpers and switches are set as indicated in Table 4 and 5 (PC-driven mode) 3. Plug the USB connector into the PC 4. Plug the mains wire into th e “MAINS POWER” connector. Plug the mains wire into the mains voltage. 5. After a few seconds during which the MCU setup operations and frequency measurement operation take place, a popup window indicating that the device has been recognized appears in the PC. As soon as the popup appears, it is possible to connect the thermostat board and the thermostat GUI software by pushing the virtual button “Connect”. For troubleshooting issues in standalone mode, verify the following:
- If no LED is ON, check the jumpers (they have to be set as in Table 4, standalone mode) or replace the fuse
- If the LEDs seem OK, reset the STM8 microcontroller using button SW1. Otherwise, unplug the board from the mains, discharge the VDD supply with a short-circuit between VDD and GND and plug the board back to the mains. For troubleshooting issues in PC GUI driven mode, verify the following:
- Ensure that switch SW8 is in the “GUI MODE” position
- Check that the correct COM port is selected (refer to the GUI “Help” menu for details)
- Repeat the startup operation, in particular if mains voltage has been turned off, ensuring that the USB cable is plugged in before the mains wire is connected (i.e. the interface side must by powered on before the control side).
- If no popup appears in the PC, just wait a few seconds before connecting the GUI after the board has been powered ON.
3.5.3 Operating modes
When the board works in standalone mode, control parameters to be considered (pulses timings, temperatures, fridge version, etc.) are the last ones uploaded in the GUI. If no parameter has ever been uploaded, the default values are those shown in Table 3, factory settings. In standalone mode, the temperature order is set by means of the two push buttons TEMP + and TEMP-, indicated by the five green LEDs (see Figure 2), and the AC loads are driven according to the order, to the sensed temperature and to the door switch. In PC GUI mode, the user can upload the control parameters loaded in the STM8 MCU, check them and eventually modify them. Temperature order is no longer displayed using the
5 LEDs - D4, D5, D7, D8, D9 - but is displayed in the GUI only (virtual LEDs VL, L, M, H,
VH). AC loads can be driven not only according to temperature, but their state can be forced by the GUI in debug mode (see Section 3.6.3 for details). The user can put the STM8 in halt mode by holding button SW3 “TEMP -” for 5 s. This low- power mode can be exited by a single push on SW4, “TEMP+” button. A beep warns at each halt mode enter/exit. It should be noted that, since push buttons SW3 and SW4 are disabled when the door is open, the user cannot enter/exit halt mode if the DOOR switch SW2 (otherwise the external switch wired to connector J15) is in the open position.
Using the STEVAL-IHT001V2 thermostat kit UM1542 20/43 Doc ID 023172 Rev 1
3.5.4 Instructions for the GUI software
In order to use the GUI of the STEVAL-IHT001V2 kit, a recent version of Windows (starting from Windows XP with SP3) must be installed on the user’s computer. To install the PC software (GUI) tool:
- Put the companion CD-ROM into the PC
- Browse the CD-ROM directory to locate the GUI setup executable file
- Double-click on the GUI setup executable file
- Follow the instructions as they appear on the screen An insulated interface is embedded in the board. By means of the STM32 MCU, the user is able to manage/monitor the control parameters of the thermostat. For more details please refer to the GUI “Help” menu.
3.6 GUI windows description
3.6.1 Temperature control tab
Choosing one of the temperature orders is done using the “thermostat order” switch position on the GUI (Figure 7) or using the temp selector push buttons “TEMP+” and “TEMP-” on the board. Note: If “Thermostat order” or “Led temperature” = VL, then “evaporator temperature order” = “evaporator temperature order 1 - Very Low” If “Thermostat order” or “Led temperature” = L, then “evaporator temperature order” = “evaporator temperature order 2 - Low” If “Thermostat order” or “Led temperature” = M, then “evaporator temperature order” = “evaporator temperature order 3 - Medium” If “Thermostat order” or “Led temperature” = H, then “evaporator temperature order” = “evaporator temperature order 4 - High” If “Thermostat order” or “Led temperature” = VH, then “evaporator temperature order” = “evaporator temperature order 5 - Very High” The value of the five temperature orders and temperature hysteresis has to be set according to the appliance and the desired cabinet temperature for each operation. They is displayed through the five virtual LEDs shown in Figure 7. Thermostat order, evaporators temperature orders and temperature hysteresis are sent and received by clicking on the “Set” or “Get” buttons, respectively. Note that the default evaporators temperature orders and temperature hysteresis are given in Appendix G, and can be retrieved by clicking on the “Restore Default” push button.
Figure 7. GUI - temperature control tab
3.6.2 Timing control tab
Figure 8. GUI - timing control window zero voltage by the MCU in order to synchronize the MCU orders with the AC mains voltage.
3.6.3 Force debug
no effect until the “Debug Active” button is pushed.
- Clicking on the “Compressor/Fan” button turns on Q1 and Q3, i.e. the compressor and fan.
- Clicking on the “Light Bulb” button turns on Q4, and then the bulb lights up.
- Clicking on the “Defrost” button turns on Q2, and then the defrost resistor starts to heat. Note: The defrost and compressor loads cannot be switched on at the same time. Setting defrost resets compressor, and vice-versa. The light bulb and fan cannot be switched on at the same time. The fan switches off as soon as the light bulb switches on. In order to go back to the “normal” mode, the user must click on the “Debug” button. In this case, all the virtual button green lights turn off.
Figure 9. GUI - debug mode frame
3.6.4 Parameter measurements
information (running period and duty cycle) and the mains frequency. For more information refer to the “Help” menu of GUI software. can be set in the “Options” window.
UM1542 Using the STEVAL-IHT001V2 thermostat kit Doc ID 023172 Rev 1 23/43
3.6.5 Saving data
The user can choose to update the STM8 MCU firmware with the timing and temperature parameters used. A dedicated button allows, in fact, uploading of these parameters. Otherwise, the STM8 MCU is not updated and default parameters is used for the next switch-on of the thermostat. The current parameters can also be saved using the GUI. A .tfs file is available for uploading. Please note that in this case, the MCU is not programmed with the current values.
4 Conclusion
This document helps cold appliance designers to use STEVAL-IHT001V2 thermostat kit. The tool can be used to:
- Check the immunity of this ST solution in standalone mode
- Easily check the appliance efficiency gains by reduction of the hysteresis threshold
- Define better management of the defrost cycles to improve the overall efficiency
- Adapt the software - using the GUI - and the hardware for other dedicated designs (control of different loads (conduction time of the ACS), adapt gate pulse widths and synchronization, implement potentiometer control, implement light dimming, etc.)
UM1542 Thermal sensor linearization Doc ID 023172 Rev 1 25/43 Appendix A Thermal sensor linearization An NTC thermistor is a resistor whose value decreases when its temperature increases. The thermal law is exponential, as shown in Equation 3: Equation 3 To create a simple voltage sensor, it is better to linearize the temperature response using a constant resistor (R49 in schematic, Appendix B) added in series with the NTC. A voltage divider is then implemented. The voltage across R49 follows the supply voltage (Vdd) according to the relationship below: Equation 4 To make the relationship of Equation 4 vary linearly, it's sufficient to ensure that the second order derivative is zero. Equation 5 gives the R49 value to ensure this condition. Equation 5 To linearize the voltage response of the M2020 5 k from EPCOS, between -20 and +5 °C, a 30 kΩ resistor should be chosen for R49. In this temperature range, VS varies according to Equation 6, for a 5 V supply: Equation 6 Figure 10 gives the variation of VS and the linear value given by Equation 6, versus the temperature sensed by the NTC. )11( 0 0)( TT B NTC RTR dd NTC NTC S VRTR TRV ⋅+= 49)( )(2 49 TR TR dT d TRdT d R NTC NTC NTC Vl T() T 51.84+
Figure 10. Linear voltage in function of the NTC resistor (for a 5 V power supply)
Figure 11. Control side schematic
Figure 12. Control side schematic - STM8
Figure 13. Interface side schematic
Figure 14. Additional pads schematic
- One LED replacing the TEMP push button (remove 0 Ω resistor R19, fit LED D11 and resistor R48).
- One LED replacing the buzzer (remove 0 Ω resistor R9 and fit LED D12 and resistor R50)
- One more push button replacing LED2 (remove R33, fit R22, R45, C35 and push button SW5).
- One potentiometer replacing the TEMP+ push button (remove 0 Ω resistor R20, fit R21, C34, and potentiometer R44).
Figure 15. Placement of additional pads
Table 6. BOM
Table 6. BOM (continued)
have been taken in order to implement tests in agreement with the EN61000-4-4 standard. EUT was placed on an insulation support 0.1 m above the ground reference plane. Bursts were directly coupled with equipment. The test generator was placed directly on, and bonded to, the ground reference plane. The board was not connected to the earthing system. Figure 16. Test setup
- Polarity: positive/negative
- Burst duration: 15 ms ± 20% at 5 kHz (Figure 17) – 0,75 ms ± 20% at 100 kHz
- Burst period: 300 ms ± 20%
- Duration time: 1 minute
- Applied to: supply voltage line and neutral AM12279v1 Bursts generator Thermostat board NTC resistor Blocks of ice Loads
The generic graph of a fast transient burst is shown in Figure 17. Figure 17. General graph of a fast transient/burst performance, without operator intervention, after the disturbance ceased. available on the CD-ROM included with the STEVAL-IHT001V2.
A SWIM connector is present on the board to allow programming/debugging operations.
- Programming mode procedure: 1. Unplug the board from the mains voltage 2. Ensure that the jumpers and switches are set as indicated in Table 7 - programming mode; in order to provide the MCU with 5 V power supply from USB 3. Connect the programmer to the SWIM connector (J2 in Figure 5) 4. Plug in the mini-USB 5. Continue with usual programming procedures. Only if an insulated AC source is used to supply the mains voltage, can the board be used in debug mode, i.e. both the communication side and the control side are supplied by the USB, but the ACS are supplied by the mains voltage and the board is fully working.
- Debugging mode procedure: 1. Plug an insulated AC source to supply STEVAL-IHT001V2 board (J14 header) 2. Connect the loads on the thermostat board (see Figure 2) 3. Ensure that the jumpers and switches are set as indicated in Table 7 - debugging mode; in order to provide the MCU with 5 V power supply from USB 4. Plug in the mini-USB 5. Power on the insulated AC source 6. Continue with usual debugging procedures. This operating mode is allowed only for expert users. Warning: Please take careful note of the jumper configuration given in Table 7 before powering up the board, whatever the mode of operation. Incorrect jumper configuration with a non- insulated power source may result in damage to the PC.
Table 7. Jumper configuration in programming and debugging modes
- This debugging mode refers to the possibility to pot entially debug a new different firmware uploaded in the
operating mode offered by the PC-GUI software, nothing to do with the debugging of firmware.
- Only if an insulated power source is used.
STM32, and input is the contrary. Table 8. PC interface parameters
frequency values used in different countries. voltage) output DC current capabilities are included for information. Table 9. C29 capacitor value according to the country
102 V to
220 V to
187 V to
Revision history
Table 10. Document revision history 10-Sep-2012 1 Initial release.