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Xinyuan-LilyGO / LilyGo-EPD47

GNU General Public License v3.0
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Powersave mode for the touchscreen? #17

Closed ElementW closed 2 years ago

ElementW commented 3 years ago

At idle, the touchscreen sold with the EPD47 consumes approximately 2 mA. The ESP32, when in deep sleep, consumes power in the range of microamperes; thus making the touchscreen the biggest power consumer on the board.

For wire-powered applications this is acceptable, however when battery-powered from e.g. a 2200 mAh 18650 cell this would drain power in under 1100 h = ~48 days. Not too short in its own regard, but considering the device will probably be idle most of the time it would be great if the touchscreen power draw could be reduced further.

Removing power from the screen could've been a possibility in certain scenarios but the schematics show it is directly connected to VDD3V3 which can't be disabled through PWR_EN like 3V3 can.

I know the touchscreen controller isn't identified (https://github.com/Xinyuan-LilyGO/LilyGo-EPD47/issues/2#issuecomment-757579958), but is there information on how to trigger some sort of powersave mode, or to reduce the idle screen scanning rate?

lewisxhe commented 3 years ago

Unfortunately, for the touch controller, we do not have detailed information. Although the manufacturer provides a sleep command, I have tested it and it can reduce about 500uA, the minimum is only 1.5mA, if there is no need to touch, I think it is still disabled to save power consumption.