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esp-01 won't boot with servo connected to gpio 2

PostPosted: Sat Jun 11, 2016 1:16 am
by jayekub
i'm guessing the state of gpio 2 is influencing the boot loader somehow? i know that the state of gpio 0 on boot controls whether to enter programming mode, but it seems gpio 2 has an effect too?

when i apply power with gpio 2 connected to the control wire of a futaba s3003, both the red and blue LEDs stay lit, and the servo makes a chugging sound. if i pull gpio 2 low with a 10k resistor, the lights do the same thing. with gpio 2 floating or high, it boots normally.

once booted, i can connect the servo and control it without problems. so i think that rules out any sort of power stability issues caused by the draw from the servo (i have a 10uF cap before my 3.3v regulator and a 100uF cap after)?

i feel like i saw a table somewhere showing that gpio 2 affects the boot loader, but i can't find it now. if it does, and i need to keep it high/floating when powering on, how can i do this (my electronics knowledge isn't very deep)? can i use a diode or transistor to prevent the servo control wire from influencing the gpio pin? or maybe a pull-up resistor to keep it high until driven?

any ideas are appreciated!

Re: esp-01 won't boot with servo connected to gpio 2

PostPosted: Sat Jun 11, 2016 1:10 pm
by jayekub
and right after posting that i tested a pull-up resistor. works like a charm!