ESP32 TTGO T1 power demo

ChargeLevelTTGO.ino

//this code will show you the battery charge left on the screen
//and dim the screen (to conserve power)
//and go to sleep when you press the left builtin button
//to wake it up again, just hit the reset button on the side


//download as zip and add to libraries folder in Arduino folder https://github.com/pangodream/18650CL
#include <Pangodream_18650_CL.h> 

#define ADC_PIN 34
#define CONV_FACTOR 1.8
#define READS 20
Pangodream_18650_CL BL(ADC_PIN, CONV_FACTOR, READS);

#include <TFT_eSPI.h>
#include <SPI.h>

TFT_eSPI tft = TFT_eSPI();  // Invoke library, pins defined in User_Setup.h

#define BUTTON_PIN_BITMASK 0x800000000 // 2^35 in hex

void IRAM_ATTR goToSleep() {
  esp_deep_sleep_start();
}

void setup() {
  tft.init();
  tft.setRotation(1);
  attachInterrupt(0, goToSleep, CHANGE);

  //set screen Back Light brightness
  pinMode(TFT_BL, OUTPUT);
  ledcSetup(0, 5000, 8); // 0-15, 5000, 8
  ledcAttachPin(TFT_BL, 0); // TFT_BL, 0 - 15
  ledcWrite(0, 1); // 0-15, 0-255 (with 8 bit resolution); 0=totally dark;255=totally shiny
}

void loop() {
  tft.fillScreen(TFT_BLACK);
  tft.setTextColor(TFT_WHITE, TFT_BLACK);  
  tft.drawFloat(BL.getBatteryChargeLevel(), 3, 0, 80, 4);

  delay(1000);
}