SimcomA76xx

Arduino library for the SimCom A76xx series (including A7670E, A7682E, A7600) LTE modems.

This library focuses on stability, predictable AT command parsing, and advanced network management, specifically designed for Arduino environments.

⚠️ DISCLAIMER: This library is in its early development phase. APIs are subject to change as we refine the features. Use with caution in production environments.

Why this library?

• Strict Band Management: Easily restrict the modem to specific LTE/GSM bands to match your antenna's tuning.
• Smart Parsing: Handles command echoes and modem URCs (Unsolicited Result Codes) gracefully without crashing.
• Reliable Networking: Built-in methods for APN configuration and network registration validation.

Installation

PlatformIO

Add to your platformio.ini:

lib_deps =
    soosp/SimcomA76xx @ ^0.2.0

Arduino IDE

Search for SimcomA76xx in the Library Manager (Sketch → Include Library → Manage Libraries).

Install manually

1. Download the repository as a ZIP.
2. In the Arduino IDE, go to Sketch -> Include Library -> Add .ZIP Library. For PlatformIO, extract the ZIP file into the lib directory in your project folder.

Quick Example

#include <Arduino.h>
#include <SimcomA76xx.h>

SimcomA76xx modem;

void setup() {
    // For logging
    Serial.begin(115200);
    // Underlying modem interface (RX pin 40, TX pin 39)
    Serial2.begin(115200, SERIAL_8N1, 40, 39);

    // Modem power pin connected to pin 6
    modem.begin(Serial2, 6);

    Serial.println(F("Waiting for modem to boot..."));
    if (modem.waitForReady()) {
      Serial.println(F("Modem is READY."));
    } else {
      Serial.println(F("Modem timeout. Check wiring/power."));
      while(1);
    }    
}

void loop() {
    // Get Signal Quality
    int csq = modem.getSignalQuality();
    Serial.print(F("Signal: ")); Serial.println(csq);

    delay(1000);
}

Using with SafeSerial on ESP32

#include <Arduino.h>
#include <SafeSerial.h>
#include <SimcomA76xx.h>

SafeSerialClass modemPort;
SimcomA76xx modem;

void setup() {
    // For logging (using Serial as physical port)
    SafeSerial.begin(115200);
    vTaskDelay(pdMS_TO_TICKS(1500));
    // Underlying SafeSerial object (RX pin 40, TX pin 39) for modem using Serial2 as physical interface
    modemPort.begin(Serial2, 115200, SERIAL_8N1, 40, 39);
    // Modem is using SafeSerial. Power pin connected to pin 6
    modem.begin(modemPort, 6);

    SafeSerial.println(F("Waiting for modem to boot..."));
    if (modem.waitForReady()) {
      SafeSerial.println(F("Modem is READY."));
    } else {
      SafeSerial.println(F("Modem timeout. Check wiring/power."));
      while(1);
    }    
}

void loop() {
    // Get Signal Quality
    int csq = modem.getSignalQuality();
    SafeSerial.printf(F("Signal: %u\n"), csq);

    vTaskDelay(pdMS_TO_TICKS(1000));
}

Thread Safety (ESP32)

On ESP32, all AT transactions are protected by a recursive FreeRTOS mutex, making it safe to call library methods from multiple tasks simultaneously.

The default lock timeout is 10000 ms. If your application uses long-running concurrent operations, increase it with:

modem.setMutexTimeout(15000);

On other platforms (AVR, STM32, ESP8266) the mutex is a no-op and has no overhead.

Recommendations:

• For fully thread-safe operation on ESP32 series MCUs, recommended to use SafeSerial library instead of using the low level Serial ports directly.

Contributing

As this is an early-stage project, feedback and Pull Requests are welcome!

License

Distributed under the MIT License. See LICENSE for more information.

Notice: Portions of this software were generated using AI language models. This code is provided "as is".

Authors

Created in 2026 by Péter Soós.