Datasheet > ST72251

ST72251

更新时间： 2024-11-20 22:42:43

品牌	Logo	应用领域
意法半导体 - STMICROELECTRONICS		/
页数	文件大小	规格书
11页	70K
描述
ST7 KEYPAD DECODING TECHNIQUES, IMPLEMENTING WAKE-UP ON KEYSTROKE

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ST72251 数据手册

APPLICATION NOTE

ST7 KEYPAD DECODING TECHNIQUES, IMPLEMENTING

WAKE-UP ON KEYSTROKE

by Microcontroller Division Application Team

INTRODUCTION

The goal of this application note is to present an example of the use of the HALT mode.

In this application, the MCU (here a ST72251) is waked up by an external interrupt caused by

someone pressed a key on the 4x4 matrixed keypad.

1 ST7 / KEYBOARD INTERFACE

Rows are connected to inputs with pull-up and interrupts (Port C). Columns are connected to

Port A configured as output. The result of the interrupt (the value of the pressed key) is sent on

LEDS (Port B) and stored into the X register. In our configuration, we have to add 4 pull-up re-

sistors on Port A (from PA0 to PA3) to be able to apply a high level on the corresponding pads.

Figure 1. ST7 / keypad interface set-up

4x100k

8x560

PC0

PC1

PC2

PC3

ST7

PA0

PA1

PA2

PA3

GND

AN980/1098

1/10

12 3 4 5 6 7...11

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型号	品牌	获取价格	描述	数据表
ST722511R6T1	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN
ST722511R6T1S	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN
ST722511R6T3	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN
ST722511R6T3S	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN
ST722511R6T6	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN
ST722511R6T6S	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN
ST722511R6T7	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN
ST722511R6T7S	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN
ST722511R7T1	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN
ST722511R7T1S	STMICROELECTRONICS	获取价格	8-BIT MCU WITH NESTED INTERRUPTS, EEPROM, ADC, 16-BIT TIMERS, 8-BIT PWM ART, SPI, SCI, CAN