Arduino Uno and Quectel EC25

Projects Networking, Protocols, and Devices
5

I have a number of Quectel modems but are in the main on custom PCBs
the exception is a Quectel Mini PCIe EVB Kit fitted with a EC21 evaluation module

using an ESP32 with a RS232-TTL module I cross connected 9-pin D-type connector pins 2 and 3 to the RS232 9-pin D-type connector on the kit, e.g.

image
image1037×778 103 KB

ran the following code

// ESP32  Serial1 test - for loopback test connect pins 16 and 17

#define RXD1 16
#define TXD1 17

void setup() {
  // initialize both serial ports:
  Serial.begin(115200);
  //Serial1.begin(115200, SERIAL_8N1, RXD1, TXD1);
  Serial1.begin(115200, SERIAL_8N1, RXD1, TXD1);
  Serial.println();
  Serial.println("\n\nESP32 serial1  test Rx pin 16 Tx pin 17");
  Serial.write("   for loopback test connect pin 16 to pin 17\n");
}

void loop() {
  // read from port 1, send to port 0:
  if (Serial1.available()) {
    int inByte = Serial1.read();
    Serial.write(inByte);
  }

  // read from port 0, send to port 1:
  if (Serial.available()) {
    int inByte = Serial.read();
    //Serial.write(inByte);
    Serial1.write(inByte);
  }
}

typing AT commands on the serial monitor I get response

ESP32 serial1  test Rx pin 16 Tx pin 17
   for loopback test connect pin 16 to pin 17
at
OK
at+cgmi
Quectel
OK
at+cgmr
EC21EFAR06A06M4G
OK
at+cgmm
EC21
OK
at+csq
+CSQ: 15,99
OK
at+cimi
+CME ERROR: 3

I get an error to AT+CIMI (returns IMSI of the SIM card) becuase I don't have a SIM card in the holder

how is your EC25 connected to the UNO and how is it powered?