Power failure comparator, nRF52811

[Aftab]

Hello,

nRFSD5 v16.0, softdevice v.7.0.1, nRF52811

I want to detect power failure/low battery voltage using POF feature of nRF52811 chip. Here is the code I'm using:

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#include "nrf_gpio.h"
#include "nrfx_uart.h"
#include "nrfx_comp.h"
#include "nrfx_systick.h"
#include "nrf_log.h"

#include "cue_driver.h"

static void sys_evt_dispatch(uint32_t sys_evt) { 
    if (sys_evt == NRF_EVT_POWER_FAILURE_WARNING) { 
        //testData = 0; 
        NRF_LOG_INFO("Power failure...");
    } 
}

void pof_init(){
    uint32_t err_code;

    err_code = sd_power_pof_enable(POWER_POFCON_POF_Enabled << POWER_POFCON_POF_Pos);
    APP_ERROR_CHECK(err_code);

    err_code = sd_power_pof_threshold_set(POWER_POFCON_THRESHOLD_V27);
    APP_ERROR_CHECK(err_code);

    // Subscribe for Sys events.
    err_code = softdevice_sys_evt_handler_set(sys_evt_dispatch);
    APP_ERROR_CHECK(err_code);
}

When I compile, get following error:

undefined reference to `softdevice_sys_evt_handler_set'

I searched online but cannot find the cause of error. I found an example here but that is for SDK11. How can I do the same for SDK16.0? 

[Simonr]

Hi

The softdevice_sys_evt_handler_set is not a part of SDK v16.0.0, which is why it isn't recognized when compiling. I don't think this should be necessary in your pof_init() function. In order to enable the POF feature in newer SDKs, all you should have to do is to call the nrf_drv_power_pof_initI() function (and include the nrf_drv_power.c and .h files in your project), as that function will check whether the SoftDevice is present or not.

Best regards,

Simon

[Aftab]

Hi, thanks for reply.

I'm not sure how to use nrf_drv_power_pof_init(), like basically what parameters go into nrf_drv_power_pofwarn_config_t  and how interrupt function is used. Is there any example of it?

[Simonr]

Hi

Here are diff files of what you would need to implement in your project in order to add the POF warning in an application using the SoftDevice:

main.c:

#include "nrf_drv_power.h"

//...

static void pow_warn_evt_handler(void)
{
    NRF_LOG_ERROR("POF warning!");
    bsp_board_led_on(BSP_BOARD_LED_3);
}


/**@brief Function for initializing POF driver.
 */
static void pof_warn_init(void)
{
    ret_code_t err_code;

    static const nrf_drv_power_pofwarn_config_t pof_config =
    {
        .handler    = pow_warn_evt_handler,
        .thr        = NRF_POWER_POFTHR_V20,
    };

    static nrfx_power_config_t power_config;
    memset(&power_config, 0, sizeof(power_config));
    err_code = nrf_drv_power_init(&power_config);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_power_pof_init(&pof_config);
    APP_ERROR_CHECK(err_code);
}

//Call the pof_warn_init(); function in your main loop to init

In sdk_config.h, set NRFX_POWER_ENABLED to 1 and POWER_ENABLED to 1.

Alternatively, you can check out the documentation for the nrf_drv_power_pof_init function in the Infocenter here.

Best regards,

Simon

[Aftab]

Thank you Simonr, that will greatly help. I'll test it assap.