stm8s development (VI) Use of EXIT: Make an external interrupt button

　　In the previous articles, the use of GPIO: Light up the LED! only described the output of the IO port, not the input. Because I recommend using the interrupt method for IO as input, which can greatly reduce the CPU running time. The most commonly used function is the button function, of course, there is also the function of communicating with other chips.

　　The previous article mentioned that GPIO can be set as interrupt input through registers.

　　Configuration mode DDRCR1CR2 Configuration mode pull-up resistor

　　Input 000 Suspension input OFF

　　010 Pull-up input ON

　　001 Interrupt suspension input OFF

　　011 Interrupt pull-up input ON

　　Output 100 Open drain output OFF

　　110 push-pull output

　　1x1 output (maximum speed 10MHZ)

　　xxxTrue open-drain output is not used

　　Here we choose PC3 as the external interrupt

　　void EXIT_GPIO_Init(void)

　　{

　　PC_DDR &= 0xf7;

　　PC_CR1 |= 0x08; // Set PC3 to interrupt pull-up input

　　PC_CR2 |= 0x08;

　　EXTI_CR1 = 0x20; //PC is set to falling edge trigger

　　}

　　It should be noted here that the interrupt vector specifies the PC, that is, if several PC ports are set as interrupts, as long as one of the interrupts is responded to, the same function will be entered.

　　If you have several buttons on the same port, you can get the status of an IO port after entering the interrupt function, determine which IO is interrupted, and then perform corresponding operations.

　　#pragma vector = EXIT_PORTC_vector //0x07

　　__interrupt void EXIT_PORTC_RQHandler(void) //Interrupt service function

　　{

　　if((PC_IDR & 0x08)==0)

　　{

　　delay_nms(50); //delay 50ms, debounce

　　if((PC_IDR & 0x08)==0) // Check if it is pressed

　　{

　　while(!(PC_IDR & 0x08)); // Release detection

　　//ALL

　　}

　　}

　　}

　　Since mechanical buttons are used, there will generally be a mechanical jitter process, so after entering the interrupt function, we first do a jitter elimination process, so that we can determine the state of the button, and also prevent jitter from causing repeated interrupt functions. Finally, add a release detection to determine that the button action is completed. (TODO here you can add the operations you need)

　　Attached is the project of stm8s in IAR environment, including the initialization code of on-chip hardware such as SPI, IIC, PWM, AWU, USART, EEPROM, etc.

　　http://download.csdn.net/detail/devintt/9454188