NRFX GPIOTE API and sensing with multiple pins recovering from system off

[Christopher Hunt]

Hi there,

I've configured the NRFX API of GPIOTE to sense four pins to go from low to high. This works well while the device is on. When the device is off (via having called sd_power_system_off) then the sensing no longer appears to work. However, if I sense just one or two pins then it does work... I'm using nRF5_SDK_17.0.2_d674dde with an s140 soft device on the nRF52840 DK.

I'm wondering if I'm experiencing some race conditions as discussed in other threads.

Here's how my main calls up the GPIOTE initialisation function:

static void gpio_init()
{
    ret_code_t err_code;
    nrfx_gpiote_in_config_t pir_pin_config = NRFX_GPIOTE_CONFIG_IN_SENSE_LOTOHI(false);

    if (!nrfx_gpiote_is_init())
    {
        err_code = nrfx_gpiote_init();
        APP_ERROR_CHECK(err_code);
    }

    err_code = nrfx_gpiote_in_init(m_left_entry_exit_outside_pir_pin, &pir_pin_config, on_gpio_in_evt);
    APP_ERROR_CHECK(err_code);
    nrfx_gpiote_in_event_enable(m_left_entry_exit_outside_pir_pin, true);

    err_code = nrfx_gpiote_in_init(m_left_entry_exit_inside_pir_pin, &pir_pin_config, on_gpio_in_evt);
    APP_ERROR_CHECK(err_code);
    nrfx_gpiote_in_event_enable(m_left_entry_exit_inside_pir_pin, true);

    err_code = nrfx_gpiote_in_init(m_right_entry_exit_outside_pir_pin, &pir_pin_config, on_gpio_in_evt);
    APP_ERROR_CHECK(err_code);
    nrfx_gpiote_in_event_enable(m_right_entry_exit_outside_pir_pin, true);

    err_code = nrfx_gpiote_in_init(m_right_entry_exit_inside_pir_pin, &pir_pin_config, on_gpio_in_evt);
    APP_ERROR_CHECK(err_code);
    nrfx_gpiote_in_event_enable(m_right_entry_exit_inside_pir_pin, true);
}

This function is called each time the device wakes up from sleep. I'm assuming that the NRFX GPIOTE API is built to handle the situation where GPIO events exist on entry otherwise the one/two sensing scenario wouldn't work.

Thanks for any pointers. This behaviour has been troubling me for a few days.

[Christopher Hunt]

ovrebekk said:

Do you know if there is any chance that one of the 4 input pins are already set when you enter sleep?

I’m unsure. However, I’m thinking that the nrfx interrupt handler should see this not to be the case. 

[ovrebekk]

Hi 

Have you checked that the code is actually entering sleep, or might it be continuing after the call to sd_power_system_off?

Is the issue consistent, or will it only happen a certain percentage of the time?

Best regards
Torbjørn

[Christopher Hunt]

ovrebekk said:

Have you checked that the code is actually entering sleep, or might it be continuing after the call to sd_power_system_off?

I’m reasonably sure it is going to sleep given that the log messages on startup are displayed when I cause a gpio event. How else might I tell?

[Christopher Hunt]

ovrebekk said:

Is the issue consistent, or will it only happen a certain percentage of the time?

The issue is consistent. When the device is reset then all is well. After the first sleep, causing a gpio event always fails to be handled.

[ovrebekk]

Hi 

Are you able to share your code project, so I can take a closer look at the code, and try to reproduce the issue?

I can make the case private if you want, so you don't have to make the code available in public. 

Best regards
Torbjørn

[Christopher Hunt]

ovrebekk said:

Are you able to share your code project, so I can take a closer look at the code, and try to reproduce the issue?

Sure thing. I’ll share a reproducer tomorrow (+11 UTC here). Thanks for the follow up.