Using mbedTLS MQTT in Tiva C series without RTOS

Mbed TLS
22

I believe the code uses ring buffer to get data using mbedtls_net_recv function. : Yes; you will have to implement ring buffer functions in rng1.c files.
You donot need CS1.h and other files while implementing and using rin1.c/.h files.

Create rng1.c/.h files and then Place these .c and .h files in mbedtls folder.

23

Hi Urvi,

I’m facing couple of issue here. Can you please help me with it?

  1. The CS1.c/.h files are not needed but RNG1.c.h use it if #define RNG1_CONFIG_REENTRANT is 1. So should I make it 0?

  2. The function call for my_mqtt_publish in MqttDoStateMachine function has less arguments than needed. I think that function was modified later and called in beginning using this piece of code
    res = xQueueReceive(APP_MsgQueue, &msg, 0);
    if (res==errQUEUE_EMPTY) {
    /* nothing in queue /
    } else {
    if (msg.msgKind==APP_MQTT_MSG_CONNECT) {
    MQTT_state = MQTT_STATE_DO_CONNECT;
    } else if (msg.msgKind==APP_MQTT_MSG_DISCONNECT) {
    MQTT_state = MQTT_STATE_DO_DISCONNECT;
    } else if (msg.msgKind==APP_MQTT_MSG_PUBLISH) {
    LWIP_DEBUGF(MQTT_APP_DEBUG_TRACE,(“Publish to broker\r\n”));
    my_mqtt_publish(mqtt_client, msg.publish.topic, msg.publish.payload, NULL);
    if (msg.publish.topic!=NULL) {
    vPortFree((void    )msg.publish.topic);
    }
    if (msg.publish.payload!=NULL) {
    vPortFree((void*)msg.publish.payload);
    }
    MQTT_state = MQTT_STATE_CONNECTED;
    }
    }

I think the xQueueReceiveis used for freeRTOS and not for our projects. So I called the function in one of the switch cases but that is this

case MQTT_STATE_DO_PUBLISH:
  LWIP_DEBUGF(MQTT_APP_DEBUG_TRACE,("Publish to broker\r\n"));
  my_mqtt_publish(mqtt_client, NULL);
  MQTT_state = MQTT_STATE_CONNECTED;
  break;

and this gives error because the function deffinition is different.
Any idea how to do this?

  1. In function ProcessLWIP there is function call for ethernetif_input which I’m not able to locate. I think this is defined in #include “ethernetif.h” which is not available anywhere.

  2. The request to the broker needs to be POST and GET which I think I saw in some file but I’m not able to locate it. Do you have an example where you’re making a request for POST or GET using these files and functions? I’ll be able to implement using that as a reference.

Thank you. And sorry for so many questions. I have an existing project and I’m trying to implement mqtt and I don’t have too much time.

Regards,
Deepak

24

Hi,

  1. Make it 0 if you are not using RTOS: #define RNG1_CONFIG_REENTRANT 0
  2. YOu can generate events fro your application code viz. Connect to broker/ publish data to broker etc. By doing so you can remove piece of code given at starting of “MqttDoStateMachine()” function.
  3. You can modify publish function definition as : my_mqtt_publish(mqtt_client, msg.publish.topic, msg.publish.payload, NULL);
  4. YOu can avoid that “ethernetif_input()” if you are aware of using lwip stack.
  5. While using mqtt, you don’t need POST/GET method. It is required when you go for WS protocol i.e. web socket protocol.