Update examples 20 and 21 to show how to use setPacketCfgPayloadSize with custom packets

examples/Example20_SendCustomCommand/Example20_SendCustomCommand.ino

@@ -62,7 +62,13 @@ void setup()
   // Let's configure the module's navigation rate as if we were using setNavigationFrequency
 
   // Let's create our custom packet
-  uint8_t customPayload[MAX_PAYLOAD_SIZE]; // This array holds the payload data bytes
+  uint8_t customPayload[MAX_PAYLOAD_SIZE]; // This array holds the payload data bytes. MAX_PAYLOAD_SIZE defaults to 256. The CFG_RATE payload is only 6 bytes!
+
+  // setPacketCfgPayloadSize tells the library how many bytes our customPayload can hold.
+  // It is more memory-efficient to call setPacketCfgPayloadSize before .begin (to avoid creating a new buffer, copying across
+  // the contents of the old buffer and then deleting the old buffer). But let's call it here just to prove that we can.
+  myGNSS.setPacketCfgPayloadSize(MAX_PAYLOAD_SIZE);
+
   // The next line creates and initialises the packet information which wraps around the payload
   ubxPacket customCfg = {0, 0, 0, 0, 0, customPayload, 0, 0, SFE_UBLOX_PACKET_VALIDITY_NOT_DEFINED, SFE_UBLOX_PACKET_VALIDITY_NOT_DEFINED};
 

examples/Example21_ModuleInfo/Example21_ModuleInfo.ino

@@ -69,6 +69,13 @@ void setup()
 
     //myGNSS.enableDebugging(); // Uncomment this line to enable debug messages
 
+    // setPacketCfgPayloadSize tells the library how many bytes our customPayload can hold.
+    // If we call it after the .begin, the library will attempt to resize the existing 256 byte payload buffer
+    // by creating a new buffer, copying across the contents of the old buffer, and then delete the old buffer.
+    // This uses a lot of RAM and causes the code to fail on the ATmega328P. (We are also allocating another 341 bytes for minfo.)
+    // To keep the code ATmega328P compliant - don't call setPacketCfgPayloadSize after .begin. Call it here instead.    
+    myGNSS.setPacketCfgPayloadSize(MAX_PAYLOAD_SIZE);
+
     if (myGNSS.begin() == false) //Connect to the u-blox module using Wire port
     {
         Serial.println(F("u-blox GNSS not detected at default I2C address. Please check wiring. Freezing."));
@@ -119,6 +126,13 @@ boolean SFE_UBLOX_GPS_ADD::getModuleInfo(uint16_t maxWait)
     // Let's create our custom packet
     uint8_t customPayload[MAX_PAYLOAD_SIZE]; // This array holds the payload data bytes
 
+    // setPacketCfgPayloadSize tells the library how many bytes our customPayload can hold.
+    // If we call it here, after the .begin, the library will attempt to resize the existing 256 byte payload buffer
+    // by creating a new buffer, copying across the contents of the old buffer, and then delete the old buffer.
+    // This uses a lot of RAM and causes the code to fail on the ATmega328P. (We are also allocating another 341 bytes for minfo.)
+    // To keep the code ATmega328P compliant - don't call setPacketCfgPayloadSize here. Call it before .begin instead.
+    //myGNSS.setPacketCfgPayloadSize(MAX_PAYLOAD_SIZE);
+
     // The next line creates and initialises the packet information which wraps around the payload
     ubxPacket customCfg = {0, 0, 0, 0, 0, customPayload, 0, 0, SFE_UBLOX_PACKET_VALIDITY_NOT_DEFINED, SFE_UBLOX_PACKET_VALIDITY_NOT_DEFINED};
 

examples/Example3_GetPosition/Example3_GetPosition.ino

@@ -43,6 +43,8 @@ void setup()
 
   Wire.begin();
 
+  //myGNSS.enableDebugging(); // Uncomment this line to enable helpful debug messages on Serial
+
   if (myGNSS.begin() == false) //Connect to the u-blox module using Wire port
   {
     Serial.println(F("u-blox GNSS not detected at default I2C address. Please check wiring. Freezing."));