MQTT data_publish() in timer handler !!

[Neculai Agavriloaie]

Hi,

Using the "mqtt_simple" example I found that the data_publish () function does not work for a timer handler.

In the case of the example below, when the data_publish () function is called by the timer, a memory violation occurs and the system is reset.

How can I resolve this issue where the data_publish () function can be called by the timer?

Regards,
Neculai

s

static void button_handler(uint32_t button_states, uint32_t has_changed)
{
      if (has_changed & button_states &
          BIT(CONFIG_BUTTON_EVENT_BTN_NUM - 1)) {


      int ret;

      ret = data_publish(&client,                               // OK, Working well !
                        MQTT_QOS_1_AT_LEAST_ONCE,
                        CONFIG_BUTTON_EVENT_PUBLISH_MSG,
                        sizeof(CONFIG_BUTTON_EVENT_PUBLISH_MSG)-1);
      if (ret) {
                   LOG_ERR("Publish failed: %d", ret);
                }
      }
}


static void data_interval_timer_handler(struct k_timer *timer)
{
    ARG_UNUSED(timer);

    int ret;
    ret = data_publish(&client,                                         // Error !!, system violation !!
                        MQTT_QOS_1_AT_LEAST_ONCE,
                        CONFIG_BUTTON_EVENT_PUBLISH_MSG,
                        sizeof(CONFIG_BUTTON_EVENT_PUBLISH_MSG)-1);
    if (ret) {
                  LOG_ERR("Publish failed: %d", ret);
              }

}

in main() function
k_timer_start(&data_interval_timer,      // start timer, OK!
                K_MINUTES(1),
                K_MINUTES(1));

[Håkon Alseth]

Hi,

 

timer and button handlers are running in interrupt context.

Socket operations cannot be called from interrupt context, so you should use a workqueue (https://docs.zephyrproject.org/latest/reference/kernel/threads/workqueue.html) or other means to run the publish function in thread context.

 

Kind regards,

Håkon

[Neculai Agavriloaie]

Hi,

I'm sorry, I had to specify that I don't use the data_publish () function simultaneously in the two interrupts: button and timer.

I just wanted to show that in the button interrupt this function works correctly (as in the mqtt_simple example in the SDK).

When I use this function in the timer interrupt it does not work and a system violation results.

In this case, the following messages appear in my terminal:

[00: 01: 10.208,160] <err> os: Exception occurred in Secure State

[00: 01: 10.208,160] <err> os: ***** HARD FAULT *****

[00: 01: 10.208,160] <err> os: Fault escalation (see below)

[00: 01: 10.208,160] <err> os: ***** BUS FAULT *****

[00: 01: 10.208,160] <err> os: Precise data bus error

[00: 01: 10.208,190] <err> os: BFAR Address: 0x50008158

Kind regards,

Neculai

[Håkon Alseth]

Hi,

 

Neculai Agavriloaie said:

I'm sorry, I had to specify that I don't use the data_publish () function simultaneously in the two interrupts: button and timer.

You shall not call socket functions in any interrupt handlers, as this will cause a fault condition.

You should use workqueue's instead, or other means to schedule the function to main (thread) context.

 

Note: button_handler is already a workqueue item, as shown here in the library itself: https://github.com/nrfconnect/sdk-nrf/blob/v1.9.0/lib/dk_buttons_and_leds/dk_buttons_and_leds.c#L294 

 

Kind regards,

Håkon