inkplate-6-arduino-library/examples/2. Advanced Inkplate Features/02-Inkplate_Low_Power/02-Inkplate_Low_Power.ino

/*
   2_Inkplate_Low_Power example for e-radionica.com Inkplate 6
   For this example you will need USB cable and Inkplate 6.
   Select "Inkplate 6(ESP32)" from Tools -> Board menu.
   Don't have "Inkplate 6(ESP32)" option? Follow our tutorial and add it: 
   https://e-radionica.com/en/blog/add-inkplate-6-to-arduino-ide/

   This example will show you how you can use low power functionality of Inkplate board. 
   In deep sleep, whole board will consume about 25uA from battery.
   Inkplate will wake every 20 seconds change content on screen. 

   NOTE: Because we are using deep sleep, everytime the board wakes up, it starts program from begining. 
   Also, whole content from RAM gets erased, so you CAN NOT use partial updates.

   Want to learn more about Inkplate? Visit www.inkplate.io
   Looking to get support? Write on our forums: http://forum.e-radionica.com/en/
   15 July 2020 by e-radionica.com
*/

#include "Inkplate.h" //Include Inkplate library to the sketch
#include "picture1.h" //Include .h files of 3 pictures. All three pictures were converted using LCD Image Converter software
#include "picture2.h"
#include "picture3.h"
#include "driver/rtc_io.h"                      //ESP32 library used for deep sleep and RTC wake up pins
const uint8_t *pictures[] = {pic1, pic2, pic3}; //This array of pinters holds address of every picture in the memory,
                                                //so we can easly select it by selecting index in array

#define uS_TO_S_FACTOR 1000000 //Conversion factor for micro seconds to seconds
#define TIME_TO_SLEEP 20       //How long ESP32 will be in deep sleep (in seconds)
RTC_DATA_ATTR int slide = 0;

Inkplate display(INKPLATE_3BIT); //Create an object on Inkplate library and also set library into 3 Bit mode (gray)

void setup()
{
  display.begin();                                         //Init Inkplate library (you should call this function ONLY ONCE)
  display.clearDisplay();                                  //Clear frame buffer of display
  display.drawBitmap3Bit(0, 0, pictures[slide], 800, 600); //Display selected picture at location X=0, Y=0. All three pictures have resolution of 800x600 pixels
  display.display();                                       //Refresh the screen with new picture
  slide++;                                                 //Update counter for pictures. With this variable, we choose what picture is going to be displayed on screen
  if (slide > 2)
    slide = 0; //We do not have more than 3 images, so roll back to zero

  rtc_gpio_isolate(GPIO_NUM_12);                                 //Isolate/disable GPIO12 on ESP32 (only to reduce power consumption in sleep)
  esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR); //Activate wake-up timer -- wake up after 20s here
  esp_deep_sleep_start();                                        //Put ESP32 into deep sleep. Program stops here.
}

void loop()
{
  //Nothing! If you use deep sleep, whole program should be in setup() because each time the board restarts, not in a loop()! loop() must be empty!
}