I want to realize a wireless keypad using ESP-32 and a matrix 4x3 keypad, connected via Bluetooth Low Energy to a master unit. I want to use deep sleep mode of ESP-32 when the keypad is not used but I need to wake up the ESP when a key is pressed, while not loosing the input. As far I understood, the matrix keypad needs the CPU running in order to understand which key has been pressed. Is there maybe some other way or component that I can use for this? Thanks for your suggestions.
There is a possibility to use lo power mcu that is build in the esp32 for reading the input while main cores are in deep sleep, but as far as i have been using it only with touch keypad.
It's not a full answer, but should help You.
Page 5, RTC block with ULP co-processor
This can handle the keypad feauture with wakeup for main core.
Hope it helped.