Serial communication with GSM/GPRS expansion module?

Hi Tom Thank you for this answer, it helped a lot. I have a problem when i use GPRSwebclientTinyGSM_D21G_HardwareSerial1.ino. I get power to the modem and the LED starts to blink. It then gets to "Waiting for network..." but then it says fail and tries again. I also tried to use an example from TinyGSM called ATdebug and it doesn't work either. I don't quite understand why it does't connect to the network. Best regards

Hi Tom Thank you for this answer, it helped a lot. I have a problem when i use GPRSwebclientTinyGSM_D21G_HardwareSerial1.ino. I get power to the modem and the LED starts to blink. It then gets to "Waiting for network..." but then it says fail and tries again. I also tried to use an example from TinyGSM called ATdebug and it doesn't work either. I don't quite understand why it does't connect to the network. Best regards

Hi, so are you getting any AT commands to/from the modem? If yes, can you make sure you're using a 2G compatible SIM card and network.

No, i'm not getting any AT commands to/from the modem. In the ATdebug example I am using, it says "Module does not respond! Check your serial wiring or check the module is correctly powered and turned on ". I know that the module is turned on as there is a blue blinking LED light.

Hi, can you share which hardware configuration you are using (switches inside the module, see manual) and the first lines of your code that has the modem configuration, then we can check, thanks

Hi, I am using IDC mode 2 that is given in the manual. This is my code, which I use from the GPRSwebclientTinyGSM_D21G_HardwareSerial1.ino example. I should not need a user or a password. // Select your modem: #define TINY_GSM_MODEM_SIM800 //#define TINY_GSM_MODEM_SIM900 //#define TINY_GSM_MODEM_A6 //#define TINY_GSM_MODEM_M590 #include const int pwr_pin = 6; // Your GPRS credentials // Leave empty, if missing user or pass const char apn[] = "internet"; const char user[] = ""; const char pass[] = ""; // Use Hardware Serial on Mega, Leonardo, Micro #define SerialAT Serial // or Software Serial on Uno, Nano //#include //SoftwareSerial SerialAT(2, 3); // RX, TX TinyGsm modem(SerialAT); TinyGsmClient client(modem); const char server[] = "cdn.rawgit.com"; const char resource[] = "/vshymanskyy/tinygsm/master/extras/logo.txt"; int port = 80; void setup() { //turn on modem with 1 second pulse on D6. pinMode(pwr_pin, OUTPUT); digitalWrite(pwr_pin, HIGH); delay(1000); digitalWrite(pwr_pin, LOW); Serial.print("HEllO"); // Set console baud rate SerialUSB.begin(115200); delay(10); // Set GSM module baud rate SerialAT.begin(115200); delay(3000); // Restart takes quite some time // To skip it, call init() instead of restart() SerialUSB.println(F("Initializing modem...")); modem.restart(); // Unlock your SIM card with a PIN //modem.simUnlock("1234"); }

Hi, please remove the line Serial.print("HEllO"); With IDC mode 2 you should be using the example with 'Serial' not 'Serial1' https://github.com/Industruino/democode/blob/master/GPRSwebclientTinyGSM_D21G_HardwareSerial/GPRSwebclientTinyGSM_D21G_HardwareSerial.ino But the code above looks fine, it has 'Serial' You have to keep in mind that the power button switches on OR off, so if your modem was on and you run the program, it will switch it off and the program will fail. Also, you need to power the INDIO via Vin with at least 8V. If still no luck, try with the IDC mode 1 (change 2 hardware switches on the board), and example for Serial1.

Hi, Tom. Thanks for this! It worked as soon as I uploaded an empty sketch, unplugged the INDIO, changed to IDC mode 1 and then powered it on again and uploaded the example for Serial1. I assume the problem was that I didn't know that the power button switches the device off aswell.