Arduino_AT_Debug.ino

// Please select the corresponding model

// #define SIM800L_IP5306_VERSION_20190610
// #define SIM800L_AXP192_VERSION_20200327
// #define SIM800C_AXP192_VERSION_20200609
//  #define SIM800L_IP5306_VERSION_20200811

#include <Arduino.h>
#include "utilities.h"

// Set serial for debug console (to the Serial Monitor, default speed 115200)
#define SerialMon Serial
// Set serial for AT commands (to the module)
#define SerialAT  Serial1

uint32_t AutoBaud()
{
    static uint32_t rates[] = {115200, 9600, 57600,  38400, 19200,  74400, 74880,
                               230400, 460800, 2400,  4800,  14400, 28800
                              };
    for (uint8_t i = 0; i < sizeof(rates) / sizeof(rates[0]); i++) {
        uint32_t rate = rates[i];
        Serial.printf("Trying baud rate %u\n", rate);
        SerialAT.updateBaudRate(rate);
        delay(10);
        for (int j = 0; j < 10; j++) {
            SerialAT.print("AT\r\n");
            String input = SerialAT.readString();
            if (input.indexOf("OK") >= 0) {
                Serial.printf("Modem responded at rate:%u\n", rate);
                return rate;
            }
        }
    }
    SerialAT.updateBaudRate(115200);
    return 0;
}

void setupModem()
{
#ifdef MODEM_RST
    // Keep reset high
    pinMode(MODEM_RST, OUTPUT);
    digitalWrite(MODEM_RST, HIGH);
#endif

    pinMode(MODEM_PWRKEY, OUTPUT);
    pinMode(MODEM_POWER_ON, OUTPUT);

    // Turn on the Modem power first
    digitalWrite(MODEM_POWER_ON, HIGH);

    // Pull down PWRKEY for more than 1 second according to manual requirements
    digitalWrite(MODEM_PWRKEY, HIGH);
    delay(100);
    digitalWrite(MODEM_PWRKEY, LOW);
    delay(1000);
    digitalWrite(MODEM_PWRKEY, HIGH);

    // Initialize the indicator as an output
    pinMode(LED_GPIO, OUTPUT);
    digitalWrite(LED_GPIO, LED_OFF);
}

void setup()
{
    // Set console baud rate
    SerialMon.begin(115200);

    setupModem();

    if (AutoBaud()) {
        Serial.println(F("***********************************************************"));
        Serial.println(F(" You can now send AT commands"));
        Serial.println(F(" Enter \"AT\" (without quotes), and you should see \"OK\""));
        Serial.println(F(" If it doesn't work, select \"Both NL & CR\" in Serial Monitor"));
        Serial.println(F(" DISCLAIMER: Entering AT commands without knowing what they do"));
        Serial.println(F(" can have undesired consiquinces..."));
        Serial.println(F("***********************************************************\n"));
    } else {
        Serial.println(F("***********************************************************"));
        Serial.println(F(" Failed to connect to the modem! Check the baud and try again."));
        Serial.println(F("***********************************************************\n"));
    }

}

void loop()
{
    while (SerialAT.available()) {
        SerialMon.write(SerialAT.read());
    }
    while (SerialMon.available()) {
        SerialAT.write(SerialMon.read());
    }

}