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I have connected a Reyax RYLR998 LoRa module to an ESP32's UART2, but AT commands passed through Hardware serial are not working.

#define RXD2 16
#define TXD2 17

void setup() {
    Serial.begin(115200);
    Serial2.begin(115200, SERIAL_8N1, RXD2, TXD2);

    Serial.print("\nSetting Lora Module \n");

    Serial2.print("AT+BAND=865000000\r\n");
    if (Serial2.available())
        Serial.println(Serial2.read());
    delay(1000);

    Serial2.print("AT+ADDRESS=1\r\n");
    if (Serial2.available())
        Serial.println(Serial2.read());
    delay(1000);

    Serial2.print((String)"AT+NETWORKID=5\r\n");
    if (Serial2.available())
        Serial.println(Serial2.read());
    delay(1000);
}

void loop() {
    while (Serial2.available()) {
        Serial.print(char(Serial2.read()));
    }
}

I tried

Serial2.print((String)"AT+NETWORKID=5\n");
Serial2.println((String)"AT+NETWORKID=5\r");
Serial2.print((String)"AT+NETWORKID=5\r");

Nothing worked, no response from AT command. Please help me I have been working on this problem for 2 days.

Connection of RYLR998 with EPS32

[![Here all AT commands works well][2]][2]

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  • 3
    Add a wiring diagram to your question and a link to the documentation for your Lora module. You appear to have set the baud rate of the Lora module's UART to 9600 but Serial2 of the ESP32 is still at 115200. These have to match. The 9600 is stored in the Lora flash for subsequent connections. Commented May 30, 2023 at 3:41
  • It is a good idea to try using an FTDI device to connect between the LORA module and the PC so you can issue commands through the serial console to LORA as your second picture shows. However, you appear to connected TX and RX incorrectly. These must be crossed over. TX on one device to RX on the other etc. Experiment with the baud rate on the serial console say 9600 or 115200. Commented May 31, 2023 at 6:10
  • Sorry, i connected it correct, wrong in image, i taken it from other place, i connected tx to rx and rx to tx Commented May 31, 2023 at 12:30
  • The documentation is here: reyax.com/products/RYLR998 . Try using the FTDI device connected to the Lora module with the USB cable connected to your PC. Ignore the ESP32 for the moment. Simply issue the command "AT" then <enter> on the serial console and it should give a response "+OK". Start with a baud rate of 115200 on the serial console. If that fails, try down to 9600. The FTDI may not be able to supply enough power for the transmit function but should be enough for the "AT" test. Commented May 31, 2023 at 16:54
  • Yes, it works perfectly when connected to USB and give AT command. How long to wait and how to wait after i give AT command to lora module through ESP32 SoftwareSerial? Commented May 31, 2023 at 18:45

1 Answer 1

Reset to default
2

I am new to Lora module and ESP32 and only playing around for a week.

I have successfully sent AT commands to RYLR998 module via ESP32 and received messages via other RYLR998 connected to another computer via USB UART serial. You need use trim() before you send your string to Serial2.(ryltr998)

trim()
[StringObject Function]
Description
Get a version of the String with any leading and trailing whitespace removed. The trim() function modifies the String in place rather than returning a new one.

Syntax
myString.trim()
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