SIM A7670C 4G LTE Development Board – Complete Setup

AT+NETOPEN         // or AT+QIOPEN / AT+QIOPEN=1,0,"TCP","example.com",80,0,0
AT+NTP?            // module-specific
AT+QIOPEN=1,0,"TCP","example.com",80,0,0  // Quectel style example
AT+QISEND=0, <len>
<send raw HTTP GET request here>
AT+QICLOSE=0

AT+QMTCFG="...",...
AT+QMTOPEN=0,"broker.hivemq.com",1883
AT+QMTCONN=0,"clientid"
AT+QMTPUB=0,0,0,0,"topic"

/* ESP32 + SIM A7670C example: HTTP POST using AT (manual TCP)
   - Connect:
     SIM_RX -> ESP32 TX2 (GPIO17)
     SIM_TX -> ESP32 RX2 (GPIO16)
     GND common
   - Power: stable VBAT for SIM module
   - Update APN, server, path, and UART pins as needed
*/

#include <HardwareSerial.h>

HardwareSerial simSerial(2); // UART2: RX2=16, TX2=17 on many ESP32
const int SIM_RX = 16; // connect to module TX
const int SIM_TX = 17; // connect to module RX
const unsigned long BAUD = 115200;

void sendAT(const char* cmd, unsigned long wait=1000) {
  simSerial.println(cmd);
  Serial.print(">> "); Serial.println(cmd);
  delay(wait);
  readResponse();
}

void readResponse(unsigned long timeout=1000) {
  unsigned long t0 = millis();
  while (millis() - t0 < timeout) {
    while (simSerial.available()) {
      char c = simSerial.read();
      Serial.write(c);
    }
  }
}

void setup() {
  Serial.begin(115200);
  simSerial.begin(BAUD, SERIAL_8N1, SIM_RX, SIM_TX);
  delay(1000);
  Serial.println("Starting SIM A7670C example...");

  // Basic check
  sendAT("AT", 500);
  sendAT("ATE0", 200); // turn off echo (optional)
  sendAT("AT+CPIN?", 500); // check SIM
  sendAT("AT+CSQ", 500); // signal
  sendAT("AT+CREG?", 500); // registration
  // Set APN - replace with your operator APN
  sendAT("AT+CGDCONT=1,\"IP\",\"internet\"");
  delay(500);

  // Optional: attach PDP
  sendAT("AT+CGATT=1", 2000);

  // Open TCP connection (module-specific; replace with your module's socket open command)
  // Example for generic module using AT+QIOPEN style - adapt as needed
  sendAT("AT+QIOPEN=1,0,\"TCP\",\"example.com\",80,0,0", 3000);
  // Wait and read +QIOPEN response...
}

void loop() {
  // Prepare HTTP POST content
  String payload = "{\"device\":\"A7670C\",\"temp\":29.5}";
  String http = "";
  http += "POST /endpoint HTTP/1.1\r\n";
  http += "Host: example.com\r\n";
  http += "Content-Type: application/json\r\n";
  http += "Content-Length: ";
  http += String(payload.length());
  http += "\r\n\r\n";
  http += payload;

  // Send length then actual data (module-specific - use appropriate send command)
  String sendCmd = "AT+QISEND=0," + String(http.length());
  simSerial.println(sendCmd);
  delay(500);
  readResponse(1000);

  // Now send raw HTTP bytes
  simSerial.print(http);
  delay(2000);
  readResponse(3000);

  // Close socket (module-specific)
  sendAT("AT+QICLOSE=0", 1000);

  // Sleep or wait before next send
  delay(60000); // send every 60s
}

AT
OK
AT+CGSN
867530912345678

AT+CPIN?
+CPIN: READY

AT+CSQ
+CSQ: 23,0   // good signal

AT+COPS?
+COPS: 0,0,"MyOperator"

AT+CREG?
+CREG: 0,1  // registered

AT+CGDCONT=1,"IP","internet"
OK
AT+CGATT=1
OK

AT+HTTPINIT
OK
AT+HTTPPARA="CID",1
OK
AT+HTTPPARA="URL","http://example.com/path"
OK
AT+HTTPACTION=0
+HTTPACTION:0,200,512
AT+HTTPREAD
... (response body)
AT+HTTPTERM
OK