Hello fellow creators,
im quite new to the entire Arduino world, but eager to get deeper in this topic. I have an Arduino UNO board and I have connected it (over two SoftwareSerial interfaces, one for communication with the GSM interface and one for the GPS interface) with an AI Thinker A9G Pudding board. I can send without any problems, and I also receive information back, but the issue I'm struggling with is, that I get a lot of disturbed bytes (that's at least my interpretation).
When I print my retrieved information on the serial monitor, I see some lines which are OK:
$GPGSV,3,1,11,04,79,204,30,39,34,167,*7A
and others are distorted:
$GNGGA,074953.000,4706.8611,r��b�ʊr�bj�43.5,M,,*40
I have followed the tutorials from the forum (and others) and I came up with this function to receive data
const unsigned int MAX_MESSAGE_LENGTH = 85;
void readGPSSerialData(){
GPSData.listen();
//delay(25);
while (GPSData.available() < 63) {}; // I get the best result, if I wait till the buffer is really full before I start reading, otherwise I get even more distorted bytes
while (GPSData.available() > 0) {
char inByte = GPSData.read(); // Get one byte of the GPS data and deletes it from the buffer
static char message[MAX_MESSAGE_LENGTH];
static unsigned int message_pos = 0;
if (inByte != '\n' && (message_pos < MAX_MESSAGE_LENGTH - 1)) {
message[message_pos] = inByte; //Add the incoming byte to our message
message_pos++;
} else {
message[message_pos] = '\0'; //Add null character to string
if (debugModus == true){
Serial.println(message); //Print the message
}
message_pos = 0; //Reset for the next message
}
nmea.process(inByte); //this function from the nmea library creates valid GPS data out of this bytes
}
AIA9G.listen(); // I'm switching back to the other SoftwareSerial
}
My baud rate is set to 9600.
I've already searched tutorials on YouTube and here, and if I follow them 1:1 I still get the same issue where others seem to work. I don't get it and would really appreciate help on this topic.
Kind regards
Chris
PS: Because more context was asked for, here is a compressed, functional version of my code, with the same issue:
#include <SoftwareSerial.h> // Library for using serial communication
#include <MicroNMEA.h> // Library for converting NEMA message
SoftwareSerial AIA9G(3, 4); // Pins 3, 4 are used as used as software serial pins RX ,TX
SoftwareSerial GPSData(10, 11); // Pins 10, 11 are used as used as software serial pins RX ,TX
const unsigned int MAX_MESSAGE_LENGTH = 85; // For retreiving serial messages
const String api_key = "XXXX"; //API Key from thingsspeak.com
char buffer[85]; // Necessary for MicroNMEA
MicroNMEA nmea(buffer, sizeof(buffer)); // Initialize NMEA convertion
const unsigned long eventInterval = 20000; // Time interval for sending GPS data
unsigned long previousTime = 0; // Timestamp for time interval
float latitude_mdeg; // Variable for extracted latitude value
float longitude_mdeg; // Variable for extracted longitude value
void setup() {
Serial.begin(19200); // baudrate for serial monitor
AIA9G.begin(115200); // baudrate for GSM shield
GPSData.begin(9600); // baudrate for GPS data
initGsmModule(); // Sends basic AT commands to configure the GPS and GSM module
}
void loop() {
unsigned long currentTime = millis(); // base for the time interval section below
readGPSSerialData();
if (currentTime - previousTime >= eventInterval) {
sendGPSData();
previousTime = currentTime;
}
AIA9G.listen();
}
void initGsmModule() {
// Enable GPS
AIA9G.println("\r");
AIA9G.print("AT+GPS=5");
AIA9G.println("\r"); //This command is used to enable GPS. When this command is sent the GPS is turned On and the LED on module for GPS starts blinking.
delay(100);
AIA9G.print("AT+GPSRD=5");
AIA9G.println("\r"); // The number defines how often the GPS data will be sent through the serial port
readA9GSerialData();
// Some more AT+Commands are sent here to AIA9G Software Serial
}
// ##### HERE ARE TWO FUNCTIONS WHERE I STRUGGLE #######
void readA9GSerialData(){
AIA9G.listen();
while (AIA9G.available() == 10) {};
while (AIA9G.available() > 0) {
char inByte = AIA9G.read(); // Get one byte of the GPS data and deletes it from the buffer
static char message[MAX_MESSAGE_LENGTH];
static unsigned int message_pos = 0;
if (inByte != '\n' && (message_pos < MAX_MESSAGE_LENGTH - 1)) {
message[message_pos] = inByte; //Add the incoming byte to our message
message_pos++;
} else {
message[message_pos] = '\0'; //Add null character to string
Serial.println(message); //Print the message
message_pos = 0; //Reset for the next message
}
}
}
void readGPSSerialData(){
GPSData.listen();
while (GPSData.available() < 63) {};
while (GPSData.available() > 0) {
char inByte = GPSData.read(); // Get one byte of the GPS data and deletes it from the buffer
static char message[MAX_MESSAGE_LENGTH];
static unsigned int message_pos = 0;
if (inByte != '\n' && (message_pos < MAX_MESSAGE_LENGTH - 1)) {
message[message_pos] = inByte; //Add the incoming byte to our message
message_pos++;
} else {
message[message_pos] = '\0'; //Add null character to string
Serial.println(message); //Print the message
message_pos = 0; //Reset for the next message
}
nmea.process(inByte); // Load the NMEA function to retreive GPS information
}
AIA9G.listen();
}
void sendGPSData() {
Serial.print("http://api.thingspeak.com/update?api_key="); // Display on Serial monitor
Serial.print(api_key);
Serial.print("&Latitude=");
Serial.print(latitude_mdeg, 6);
Serial.print("&Longitude=");
Serial.print(longitude_mdeg, 6);
Serial.println();
if (true) { //Function will follow later
AIA9G.print("AT+HTTPGET=\"https://api.thingspeak.com/update?api_key=");
AIA9G.print(api_key);
AIA9G.print("&field1=");
AIA9G.print(latitude_mdeg, 6);
AIA9G.print("&field2=");
AIA9G.print(longitude_mdeg, 6);
AIA9G.println("\r");
readA9GSerialData();
}
}
