Interfacing A9G with Arduino for AT commands testing

Question

I am trying to hook up to an A9G Pudding GSM board via an Arduino. I intend to use the onboard UART chip to facilitate TTL-UART conversion between PC and A9G.

I have initiated a software serial instance and using this to pass communication to/from the A9G and the Arduino.

Here's my code. However, all I'm getting is gibberish stuff. I've checked my connections, the link seems to exist but the encoding is mismatched. I'm communicating with the A9G at 115200 and my emulated serial is at 9600.

Could this be an issue?

#include <SoftwareSerial.h>
SoftwareSerial mySerial(10, 11); // RX, TX
void setup() {
 Serial.begin(9600); // Monitor baud rate
 mySerial.begin(57600); // Set to detected baud rate
 Serial.println("A9G Module Communication Test");
 
 // Send AT command with carriage return and line feed
 mySerial.print("AT\r\n");
 delay(1000); // Wait for response
}
void loop() {
 // Check if data is available from the A9G module
 if (mySerial.available()) {
 // Read the data from the A9G module
 while (mySerial.available()) {
 char c = mySerial.read();
 Serial.write(c); // Send it to the Serial Monitor
 }
 }
 // Check if data is available from the Serial Monitor
 if (Serial.available()) {
 // Read the data from the Serial Monitor
 while (Serial.available()) {
 char c = Serial.read();
 mySerial.write(c); // Send it to the A9G module
 }
 }
}

Here's the output on the serial monitor.

Serial console output

• hcheung: Type "AT" and press "Send" from your Serial Monitor, what do you get?
• Lee-xp: Try it with mySerial.begin(115200); since that is the default baud rtate of the A9G.
• jsotola: please do not write in all capitals ... it indicates SHOUTING which is considered impolite ... use the edit button to correct the title
• jsotola: please do not post pictures of text ... post the text instead... format as code for readability

Answer 1

You can edit your code like this.

#include <SoftwareSerial.h>
SoftwareSerial mySerial(10, 11); // RX, TX
void setup() {
 Serial.begin(9600); // Monitor baud rate to match A9G
 mySerial.begin(115200); // Set to A9G baud rate
 Serial.println("A9G Module Communication Test");
 
 // Send AT command with carriage return and line feed
 mySerial.print("AT\r\n");
 delay(1000); // Wait for response
}
void loop() {
 // Check if data is available from the A9G module
 if (mySerial.available()) {
 // Read the data from the A9G module
 while (mySerial.available()) {
 char c = mySerial.read();
 Serial.write(c); // Send it to the Serial Monitor
 }
 }
 // Check if data is available from the Serial Monitor
 if (Serial.available()) {
 // Read the data from the Serial Monitor
 while (Serial.available()) {
 char c = Serial.read();
 mySerial.write(c); // Send it to the A9G module
 }
 }
}

• Juraj: why? what is changed?
• tepalia: My serial baud rate has been changed from 57600 to 115200.
• Juraj: and why is that the right value. please write an answer without the sketch if only the baud rate is changed.
• tepalia: The serial monitor is showing garbage value. That's why I thought, the defined baud rate for A9G might not be correct.
• Juraj: but that should be in your answer. not a copy of the sketch. arduino.stackexchange.com/help/how-to-answer