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.


1 Answer 1


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

also: https://github.com/espressif/esp-idf/tree/master/examples/system/ulp


This can handle the keypad feauture with wakeup for main core.

Hope it helped.

  • \$\begingroup\$ Welcome to electronics.stackexchange.com. Keep up the good work. \$\endgroup\$
    – Maple
    Commented Jun 17, 2018 at 8:35
  • \$\begingroup\$ No problem, without help of others on this and many other forums or websites i would not have the knowledge I have. So if there is a way to give back to others what i have received when needed, i'm always willing to help. That's what community stands for, right? :) \$\endgroup\$ Commented Jun 20, 2018 at 23:54

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