Add standby mode function for TFT

[matthieuweber]

Hello !

I added and tested with success
(at least for my TFT TJCTM24024 (ILI9341 2.8" SPI)
a sleep /wake-up function to switch off/on my screen

Code could be added into TFT_eSPI.cpp / TFT_eSPI.h

TFT_eSPI.cpp 
...
/***************************************************************************************
** Function name:           sleep
** Description:             Allows the display to be put to sleep then awake again
***************************************************************************************/
void TFT_eSPI::sleep(bool value)
{
    if (value)
    {
        writecommand(0x10);         // Send command to put the display to sleep.
        delay(150);                   // Delay for shutdown time before another command can be sent.
    }
    else
    {
      //  writecommand(0x11);         // Send command to wakeup the display.
      //  delay(120);                 // Wait for the display power supplies to stabilise.
      init();               // This sends the wake up command and initialises the display
    	delay(50);            // Extra delay to stop a "white flash" while the TFT is initialising.
    }
}

TFT_eSPI.h
....
void sleep(bool value);  // Put TFT in sleep mode / and wake it up again

Best,

Matthieu

[Bodmer]

I prefer simple low level functions like this to be in the sketch rather than the base library. Alternatively an extension library can be created using the approach described here:
https://github.com/Bodmer/TFT_eFX/tree/master