Inability to sleep the nRF52832. Number of possible buttons in using the BSP module?

[BendaEng]

Hi, 

We have a custom device that has 15 buttons. Presently we use the following code to initialize and use the button interrupts. I am using a __WFE(); to wait for the next event (i.e. a button press) however when I press two specific buttons (by design) together it brings the device partially into sleep_mode. This method works sufficient for detecting the button presses, but in attempting to put the device into a lower power mode it seems that some sort of interrupt is triggering the device to come right out of the low power mode or not completely go into low power mode. The device does come out of the "low power (5mA)" mode but completes a reset in the process. The current draw drops from about 9 mA (with I2C device) down to 5 mA (likely, just without I2C device), but never drops to uA levels. My thought is that another interrupt triggers the device to come right out while keeping the I2C device off, but I'm not sure which one would do that.

/*
*
* The following contain the interrupt handlers for all button presses
*
*/
void in_pin_handler(nrf_drv_gpiote_pin_t pin, nrf_gpiote_polarity_t action)
{
   buttons_pressed = true;
   chirp_led(BLUE_LED);

   ret_code_t err_code; 
   
   if(power_off_mode)
      {
              
            //Disable power-down button to prevent System-off wakeup
                      
            for(int i = 0; i < NUM_BUTTONS; i++) {
                    
                    nrf_drv_gpiote_in_uninit(buttons[i]);
                    nrf_drv_gpiote_in_event_disable(buttons[i]);      
            }

            //Configure wake-up button
           
            for(int i = 0; i < NUM_BUTTONS; i++) {
                nrf_drv_gpiote_in_config_t in_config = GPIOTE_CONFIG_IN_SENSE_LOTOHI(false);    //Configure to generate interrupt and wakeup on pin signal high.
                in_config.pull = NRF_GPIO_PIN_PULLDOWN;                                         //Configure pulldown for input pin to prevent it from floating.
                err_code = nrf_drv_gpiote_in_init(buttons[i], &in_config, in_pin_handler);      //Initialize the wake-up pin
                APP_ERROR_CHECK(err_code);                                                      //Check error code returned
                nrf_drv_gpiote_in_event_enable(buttons[i], true);                               //Enable event and interrupt for the wakeup pin
            }
          
          //Enter System-off
          NRF_POWER->SYSTEMOFF = 1;
      }
}


//
//@brief Function for configuring: PIN_IN pin for input, PIN_OUT pin for output,
// and configures GPIOTE to give an interrupt on pin change.
//
static void gpio_init(void)
{
    ret_code_t err_code;

    nrf_gpio_cfg_output(BLUE_LED);
    nrf_gpio_cfg_output(RED_LED);
    
    if(nrf_drv_gpiote_is_init() == false)
    {
        err_code = nrf_drv_gpiote_init();
        APP_ERROR_CHECK(err_code);  
    }

    for(int i = 0; i < NUM_BUTTONS; i++) {
        nrf_drv_gpiote_in_config_t in_config = GPIOTE_CONFIG_IN_SENSE_LOTOHI(false);
        in_config.pull = NRF_GPIO_PIN_PULLDOWN;

        err_code = nrf_drv_gpiote_in_init(buttons[i], &in_config, in_pin_handler);
        APP_ERROR_CHECK(err_code);

        nrf_drv_gpiote_in_event_enable(buttons[i], true);
    }
}

Searching around I found a handful of explanations of using the BSP module along with a sleep_mode_enter() based on a button press. However, all of the documentation only shows 8 buttons available in the BSP module. Is there the ability to handle more buttons than that, 15 or more? If so what steps would need to be taken to modify the included files to allow for this? Do I need to modify the pca10040.h, bsp.h/c, boards.h/c, others? How so?

Thanks for the help!

[Jared]

Hi,

The prouduct specification states:"When the system wakes up from System OFF mode, it gets reset. For more details, see Reset behavior". You could check the reason for the reset by reading register RESETREAS. Are you using the button handling library? The library handles debouncing which could otherwise cause a pin reset. You should use a custom board file if you're using a custom board with the BSP module.

regards

Jared. 

[BendaEng]

Hi, 

Thanks for the suggestions. I am not presently using the button handling library, I've defined a buttons.h file and have initialized them as GPIOTE_CONFIG_IN_SENSE_LOTOHI as shown above. I may want to use it though as I still cannot identify the root issue of the high power. 

I've looked into the RESETREAS register before and after applying the power settings. The value never changes from 0x00000006 indicating the following. 

         1. Reset from watchdog detected

         2. Reset from soft reset detected

I am using a watchdog, but based on the value never changing and the fact that our current draw reduces to only 5 mA (from 9mA by putting our I2C device into sleep mode) it still seems like the device never actually enters a lower power mode. Could the Watch Dog be preventing entry into the sleep mode? Or what else could prevent this?

Additionally I tried to use an idle_state_handler(); which calls nrf_pwr_mgmt_run(); to set the device into System ON mode (to preserve the state of the machine better). This eliminates the resetting on wake-up button pressing, but again it doesn't seem like the device even enters a lower power mode (just turns off our I2C device).  

/**@brief Function for handling the idle state (main loop).
 *
 * @details If there is no pending log operation, then sleep until next the next event occurs.
 */
static void idle_state_handle(void)
{
    if (NRF_LOG_PROCESS() == false)
    {
        nrf_pwr_mgmt_run();
    }
}

Also, 

So I'm gathering If I define a custom_board.h file the only limitation on number of inputs to track and use with BSP is the number of I/O the device has? Is that correct that I can define 15 or more buttons this way? I may have to try this route of detecting button presses if I cannot get the power draw lower since it seems like the power management is more defined and functional with it. 

Thanks for the help!