The project folder with source codes are located on DT16.

D:\Users\tfw\Documents\Proj-IOT\04-S3_Projs\02-frtos_tasks\my_tasks

• In app_main( ), prepare the GPIO pin
  • setup pinMode, pulldown or pullup, set interrupt type.

	gpio_pad_select_gpio(BTN_PIN);
	gpio_set_direction(BTN_PIN, GPIO_MODE_INPUT);
	gpio_set_pull_mode(BTN_PIN, GPIO_PULLUP_ONLY);
	gpio_set_intr_type(BTN_PIN, GPIO_INTR_NEGEDGE);

• Then we will call gpio_install_isr_service(int intr_alloc_flags) to install the interrupt routine service (IRS) and gpio_isr_handler_add( ) to add the interrupt handler –
  • inside app_main(), add gpio_install_isr_service(0); ,
    • this function takes in a single parameter which denotes the flags for interrupt allocation. In this case, it is zero.
  • After the above, add gpio_isr_handler_add(INPUT_PIN, gpio_interrupt_handler, void *args);
    • 1st parameter – the GPIO pin
    • 2nd parameter – ISR handler function name
    • 3rd parameter – the input parameter for the ISR function. In this case, the ISR has no input parameter. Therefore, NULL is entered.

• If interrupt is triggered by the button edge of the level change, this helps to eleminate button bouncing.
• Define the interrupt handler function. This function will be called when the interrupt occurs.

void IRAM_ATTR toggleExtLedISR(void *args)
{
    gpio_intr_disable(BTN_PIN);
    isBtnPressed = true;

} // toggleExtLedISR()

• The ISR first disable the interrupt in order to avoid unnecessary triggering while handling the routine function. Then set the isBtnPressed to true.
• In Task 2 intLed, the while loop monitors the status of isBtnPressed. If true, it gets the status of Task 1 extLed and toggle its state using vTaskSuspend or vTaskResume. At the end of the toggle, it resets the isBtnPressed to false and re-enable the interrupt.
• IRAM_ATTR is to put the function in the instruction ram for better performance. There are some rules for functions in this RAM area. Search other documents for details.