MCU8MASS-481 Temporary fix for timing out waiting for start character for payload

This commit addresses the bug where the modem does not respond after issuing a publish or receieve message with a temporary fix. It also restructures the mqtt examples to publish before reading the message.

Author: M65649

examples/mqtt_polling/mqtt_polling.ino

@@ -65,16 +65,6 @@ void setup() {
 }
 
 void loop() {
-
-    String message = MqttClient.readMessage(MQTT_SUB_TOPIC);
-
-    // Read message will return an empty string if there were no new
-    // messages, so anything other than that means that there was a new
-    // message
-    if (message != "") {
-        Log.infof("Got new message: %s\r\n", message.c_str());
-    }
-
     String message_to_publish = String("Hello world: " + String(counter));
 
     bool publishedSuccessfully =
@@ -87,5 +77,16 @@ void loop() {
         Log.error("Failed to publish");
     }
 
-    delay(5000);
+    delay(2000);
+
+    String message = MqttClient.readMessage(MQTT_SUB_TOPIC);
+
+    // Read message will return an empty string if there were no new
+    // messages, so anything other than that means that there was a new
+    // message
+    if (message != "") {
+        Log.infof("Got new message: %s\r\n", message.c_str());
+    }
+
+    delay(2000);
 }

examples/mqtt_polling_aws/mqtt_polling_aws.ino

@@ -44,7 +44,6 @@ bool initMQTTTopics() {
 
 void setup() {
     Log.begin(115200);
-
     LedCtrl.begin();
     LedCtrl.startupCycle();
 
@@ -86,15 +85,6 @@ void setup() {
 
 void loop() {
 
-    String message = MqttClient.readMessage(mqtt_sub_topic);
-
-    // Read message will return an empty string if there were no new
-    // messages, so anything other than that means that there were a
-    // new message
-    if (message != "") {
-        Log.infof("Got new message: %s\r\n", message.c_str());
-    }
-
     bool published_successfully =
         MqttClient.publish(mqtt_pub_topic, "{\"light\": 9, \"temp\": 9}");
 
@@ -104,5 +94,16 @@ void loop() {
         Log.error("Failed to publish\r\n");
     }
 
-    delay(1000);
+    delay(2000);
+
+    String message = MqttClient.readMessage(mqtt_sub_topic);
+
+    // Read message will return an empty string if there were no new
+    // messages, so anything other than that means that there were a
+    // new message
+    if (message != "") {
+        Log.infof("Got new message: %s\r\n", message.c_str());
+    }
+
+    delay(2000);
 }

src/http_client.cpp

@@ -101,6 +101,10 @@ static HttpResponse sendData(const char *endpoint,
 
     SequansController.clearReceiveBuffer();
 
+    // Fix for bringing the modem out of idling and prevent timeout whilst
+    // waiting for modem response during the next AT command
+    SequansController.retryCommand("AT");
+
     // Setup and transmit SEND command before sending the data
     const uint32_t digits_in_data_length = trunc(log10(buffer_size)) + 1;
 
@@ -110,7 +114,6 @@ static HttpResponse sendData(const char *endpoint,
 
     // We receive one start bytes of the character '>', so we wait for
     // it
-
     uint64_t start = millis();
     int16_t start_character = 0;
 
@@ -191,6 +194,10 @@ static HttpResponse queryData(const char *endpoint, const uint8_t method) {
 
     SequansController.clearReceiveBuffer();
 
+    // Fix for bringing the modem out of idling and prevent timeout whilst
+    // waiting for modem response during the next AT command
+    SequansController.retryCommand("AT");
+
     // Set up and send the query
     char command[strlen(HTTP_QUERY) + strlen(endpoint)];
     sprintf(command, HTTP_QUERY, method, endpoint);
@@ -332,6 +339,10 @@ int16_t HttpClientClass::readBody(char *buffer, const uint32_t buffer_size) {
 
     SequansController.clearReceiveBuffer();
 
+    // Fix for bringing the modem out of idling and prevent timeout whilst
+    // waiting for modem response during the next AT command
+    SequansController.retryCommand("AT");
+
     // We send the buffer size with the receive command so that we only
     // receive that. The rest will be flushed from the modem.
     char command[HTTP_RECEIVE_LENGTH] = "";

src/mqtt_client.cpp

@@ -583,6 +583,11 @@ bool MqttClientClass::publish(const char *topic,
     Log.debugf("Starting publishing on topic %s\r\n", topic);
 
     SequansController.clearReceiveBuffer();
+
+    // Fix for bringing the modem out of idling and prevent timeout whilst
+    // waiting for modem response during the next AT command
+    SequansController.retryCommand("AT");
+
     const size_t digits_in_buffer_size = trunc(log10(buffer_size)) + 1;
     char command[MQTT_PUBLISH_LENGTH_PRE_DATA + digits_in_buffer_size];
 
@@ -697,6 +702,10 @@ bool MqttClientClass::readMessage(const char *topic,
 
     SequansController.clearReceiveBuffer();
 
+    // Fix for bringing the modem out of idling and prevent timeout whilst
+    // waiting for modem response during the next AT command
+    SequansController.retryCommand("AT");
+
     // We determine all message IDs lower than 0 as just no message ID passed
     if (message_id < 0) {
         char command[MQTT_RECEIVE_LENGTH] = "";
@@ -738,14 +747,10 @@ bool MqttClientClass::readMessage(const char *topic,
         }
     }
 
-    // Then we retrieve the payload
-    ResponseResult result =
+    // Then we retrieve the payload (if any)
+    const ResponseResult result =
         SequansController.readResponse((char *)buffer, buffer_size);
 
-    if (result != ResponseResult::OK) {
-        Log.warn("Failed whilst retrieving the MQTT message payload");
-    }
-
     return (result == ResponseResult::OK);
 }