// SIM card PIN (leave empty, if not defined)
const char simPIN[] = "";

// Your phone number to send SMS: + (plus sign) and country code,
//next digit should be your cell number
// SMS_TARGET Example for UK +44XXXXXXXXX
#define SMS_TARGET "+44XXXXXXXXXX"

// Configure TinyGSM library
#define TINY_GSM_MODEM_SIM800 // Modem is SIM800
#define TINY_GSM_RX_BUFFER 1024 // Set RX buffer to 1Kb

#include <Wire.h>
#include <TinyGsmClient.h>

// TTGO T-Call pins
#define MODEM_RST 5
#define MODEM_PWKEY 4
#define MODEM_POWER_ON 23
#define MODEM_TX 27
#define MODEM_RX 26
#define I2C_SDA 21
#define I2C_SCL 22

// Set serial for debug console (to Serial Monitor, default speed 115200)
#define SerialMon Serial
// Set serial for AT commands (to SIM800 module)
#define SerialAT Serial1

// Define the serial console for debug prints, if needed
//#define DUMP_AT_COMMANDS

#ifdef DUMP_AT_COMMANDS
#include <StreamDebugger.h>
StreamDebugger debugger(SerialAT, SerialMon);
TinyGsm modem(debugger);
#else
TinyGsm modem(SerialAT);
#endif

#define IP5306_ADDR 0x75
#define IP5306_REG_SYS_CTL0 0x00

bool setPowerBoostKeepOn(int en){
Wire.beginTransmission(IP5306_ADDR);
Wire.write(IP5306_REG_SYS_CTL0);
if (en) {
Wire.write(0x37); // Set bit1: 1 enable 0 disable boost keep on
} else {
Wire.write(0x35); // 0x37 is default reg value
}
return Wire.endTransmission() == 0;
}

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

// Keep power when running from battery
Wire.begin(I2C_SDA, I2C_SCL);
bool isOk = setPowerBoostKeepOn(1);
SerialMon.println(String("IP5306 KeepOn ") + (isOk ? "OK" : "FAIL"));

// Set modem reset, enable, power pins
pinMode(MODEM_PWKEY, OUTPUT);
pinMode(MODEM_RST, OUTPUT);
pinMode(MODEM_POWER_ON, OUTPUT);
digitalWrite(MODEM_PWKEY, LOW);
digitalWrite(MODEM_RST, HIGH);
digitalWrite(MODEM_POWER_ON, HIGH);

// Set GSM module baud rate and UART pins
SerialAT.begin(115200, SERIAL_8N1, MODEM_RX, MODEM_TX);
delay(3000);

// Restart SIM800 module, it takes quite some time
// To skip it, call init() instead of restart()
SerialMon.println("Initializing modem...");
modem.restart();
// use modem.init() if you don't need the complete restart

// Unlock your SIM card with a PIN if needed
if (strlen(simPIN) && modem.getSimStatus() != 3 ) {
modem.simUnlock(simPIN);
}

// To send an SMS, call modem.sendSMS(SMS_TARGET, smsMessage)
String smsMessage = "Hello MICRODIGISOFT!";
if(modem.sendSMS(SMS_TARGET, smsMessage)){
SerialMon.println(smsMessage);
}
else{
SerialMon.println("SMS failed to send");
}
}

void loop() {
delay(1);
}