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tures specific to the task, cost is relatively low. needed, customers might choose a 4, 8, 16, or 32 bit microcontroller. Figure 1. Typical MCU Block Diagram storing a program in a microcontroller, especially for high volume manufacturing.

endurance can be either 100 or 300,000 program/erase cycles. must be saved through a power down cycle. in order to execute a program, the CPU will read the first instruction from program memory. repeated until the end of the program (or an endless loop) is found. Figure 2. Typical Microcontroller Block Organization events. The power of the timers varies greatly between different MCUs.

1 TYPICAL MICROCONTROLLER APPLICATIONS

items, more than one processor can be found. Figure 5. Typical MCU Applications Figure 6. Example of MCU Task Management.

2 ADDITIONAL MICROCONTROLLER FEATURES

2.1 TIMERS

least the system has a way to recover. This is especially useful for unattended systems. counting value when the count is over, therefore sparing a waste of CPU resource. Figure 9. Standard Timer and Auto-Reload Timer Principle Figure 10. PWM Principle pulse accumulator register, recording the number of times this event has occurred.

side the output compare register. Figure 11. Input Capture and Output Capture Timer Functions

2.2 DIGITAL SIGNAL PROCESSORS (DSP)

capability and DSPs with on-chip microcontrollers.

2.3 ANALOG AND DIGITAL SIGNALS

trial control systems and automotive systems.

Figure 12. Mixed A/D System Example alog world. Various types of A/D converters that can be found. output signals are available on the microcontroller bus.

2.4 COMMUNICATION

multiplexed automotive wiring standard that is currently in use in North America. Figure 13. CAN Principle tions. In addition to microcontrollers, several peripherals also exist that support the I2C bus. The I2C bus is a two line, multi-master, multi-slave network interface with collision detection. node (microcontroller or peripheral) may initiate a message, and then transmit or receive data. nodes. Since only 2 wires are needed, it is easy to interconnect a number of devices. asynchronous serial communications. using a USART are typically much faster (as much as 16 times) than with a UART.

2.5 INTERRUPTS

depending on which flags have been set. Figure 14. Polling versus Interrupt tinually asking peripherals if they have any data ready). can be a pain but is not susceptible to glitches).

3 POWER SUPPLY ISSUES IN MCUs

offer a performance level comparable to 5 volt devices. as big, it dissipates half as much power. Figure 15. Transistor Parameter Scheme tually 3.3) Volt logic, and this will certainly lead to lower voltages in the next few years.

MICROCONTROLLERS MADE EASY “THE PRESENT NOTE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS WITH INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE CONTENT OF SUCH A NOTE AND/OR THE USE MADE BY CUSTOMERS OF THE INFORMATION CONTAINED HEREIN IN CONNEXION WITH THEIR PRODUCTS.” Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without the express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics  2000 STMicroelectronics - All Rights Reserved. Purchase of I2C Components by STMicroelectronics conveys a license under the Philips I2C Patent. Rights to use these components in an I2C system is granted provided that the system conforms to the I2C Standard Specification as defined by Philips. STMicroelectronics Group of Companies Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco - Singapore - Spain Sweden - Switzerland - United Kingdom - U.S.A. http://www.st.com