There is an error in the WDT driver SDK15.2

[kxct]

nrfx_err_t nrfx_wdt_init(nrfx_wdt_config_t const * p_config,
                         nrfx_wdt_event_handler_t  wdt_event_handler)
{
    NRFX_ASSERT(p_config);
    NRFX_ASSERT(wdt_event_handler != NULL);
    nrfx_err_t err_code;
    m_wdt_event_handler = wdt_event_handler;

    if (m_state == NRFX_DRV_STATE_UNINITIALIZED)
    {
        m_state = NRFX_DRV_STATE_INITIALIZED;
    }
    else
    {
        err_code = NRFX_ERROR_INVALID_STATE;
        NRFX_LOG_WARNING("Function: %s, error code: %s.",
                         __func__,
                         NRFX_LOG_ERROR_STRING_GET(err_code));
        return err_code;
    }

    nrf_wdt_behaviour_set(p_config->behaviour);

    nrf_wdt_reload_value_set((p_config->reload_value * 32768) / 1000);

    NRFX_IRQ_PRIORITY_SET(WDT_IRQn, p_config->interrupt_priority);
    NRFX_IRQ_ENABLE(WDT_IRQn);

    err_code = NRFX_SUCCESS;
    NRFX_LOG_INFO("Function: %s, error code: %s.", __func__, NRFX_LOG_ERROR_STRING_GET(err_code));
    return err_code;
}

When the value of reload_value is too large, the calculation will exceed the maximum allowed by uint32_t。

[Simon]

This is not an error, it is not the intention that the reload value should be bigger than 4294967295 (largest number that a 32 bit variable can hold), see WDT_CONFIG_RELOAD_VALUE in the sdk_config.h:

// <o> WDT_CONFIG_RELOAD_VALUE - Reload value  <15-4294967295> 


#ifndef WDT_CONFIG_RELOAD_VALUE
#define WDT_CONFIG_RELOAD_VALUE 2000
#endif

Best regards,

Simon

[kxct]

Please take a look at this code. Data overflow when performing multiplication。

    nrf_wdt_reload_value_set((p_config->reload_value * 32768) / 1000);

[Simon]

You are completely right, thanks for reporting it. This bug was discovered in SDK 11 as well, and has been reported and fixed (look at SDK 14.X.0). However, it seems like the the bug is reintroduced with the new nrfx drivers. I have reported the bug internally.

Best regards,

Simon

[awneil]

Another case today:

https://devzone.nordicsemi.com/f/nordic-q-a/50147/wdt-triggered-too-early