Using a Mega 2560 Rev3. The ILI9486 screen I acquired from AliExpress — a shield — has no screen-off function. I need one since this will control an audio preamplifier and I want to have a standby function where the screen is dark but the IR remote and tap power button will both activate the preamp.
So I need to know if anyone can point me to a color 3.5 inch Tft screen that will accept a screen off command and still has a SD card reader (i am storing data on it that I read for configuration).
Hi. That does not shut off the screen; it merely blackens the LCD and leaves the backlight still on.
I’m looking for something that lets me keep power to the micro-controller but not to the screen. I tried writing each of the control pins low but to no avail.
I ordered a few alternative screens so I can try to work the issue. I have a little hope for the ST7796s. Just hoping that someone knew of something. I can’t be the first person to want to do this.
I have an ILI9486 shield that I identified the current limiting resistor for the backlight on it. I replaced that resistor with a higher value to reduce the amount of current used by the backlight; I was able to cut it in half w/o appreciably dimming the display.
You could do something similar; remove the resistor, add a transistor, appropriately sized base and collector resistors and control the backlight with an I/O pin. If memory serves, A5 is unused on most shields but populated with a header pin so that would likely work w/o too much effort.