Pull-ups? We need no @#$@$ pull-ups!

A project log for D1 Mini X-Pad Shield

Adds some buttons to your ESP8266 board.

de∫hipude∫hipu 09/28/2017 at 09:503 Comments

Turns out that I have over-engineered this shield a little bit — I wanted to make sure the pins are pulled up when the buttons are not pressed, so I added a pull-up resistor to each button. But looking at the #LAMEBOY - another ESP12 handheld project, I noticed that @davedarko didn't use any pull-ups, and it works reliably for him. We dived into the datasheet a bit and did some experiments, and it turns out you really don't need them. So now I'm leaving the pads for the pull-up resistors un-populated. Perhaps I will design another version of the PCB, with the chip on the bottom side and without any pull-ups whatsoever, but for now this simplified second version works well for me.


davedarko wrote 09/28/2017 at 14:36 point

I still feel a bit uncomfortable with that, although my source is an article at, the datasheet is even weirder (having a 100k Ohm resistor pulling up the pin and a switch that connects to VCC over 100kOhm when closed)

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davedarko wrote 09/28/2017 at 14:46 point

"The internal Power-On Reset (POR) initializes the I/Os as inputs with a weak internal pull-up 100 uA current source." Page one of the datasheet... 

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