How does the pins work

This list is made with only mentioning how it handles digital logic and interrupts

DRV8825: https://www.pololu.com/product/2133

Pin	Function	Status
EN	Logic high to disable device output and indexer	Input, Internal pulldown
M0	Set step mode	Input, Internal pulldown
M1	Set step mode	Input, Internal pulldown
M2	Set step mode	Input, Internal pulldown
RST	Logic low to reset indexer and disable output	Input, Internal pulldown
SLP	Logic low to enter low-power sleep	Input, Internal pulldown
STP	Rising edge move stepper one step	Input, Internal pulldown
DIR	Logic level sets direction	Input, Internal pulldown
FLT	Logic low when in fault condition	Output, open-drain, pullup to sleep pin

Limit switch:

Pin	Function	Status
1	Endstop, need interrupt pin preferably	Output, Normaly Open

This means that we need 8 outputs that doesn't have fixed pullups and can handle boot with pulldowns on the pins. And 2 interrupt inputs with at least one that has a pullup.

As seen in the list below this means that D3 and D4 need to be inputs and one of the serial lines as output.

NodeMCU v1.0 Amica ESP-12E:

Pin	Function	Status	Can be used as
D0	GPIO16	Not usable with deepsleep, Hi-Z DIO, no interrupt	Output
D1	GPIO5	Hi-Z DIO	Output, Input, Interrupt
D2	GPIO4	Hi-Z DIO	Output, Input, Interrupt
D3	GPIO0	No Hi-Z DIO (prefere pullup)	Input, Interrupt
D4	GPIO2	Don’t connect to ground at boot time (prefere pullup)	Input, Interrupt
D5	GPIO14	Hi-Z DIO	Output, Input, Interrupt
D6	GPIO12	Hi-Z DIO	Output, Input, Interrupt
D7	GPIO13	Hi-Z DIO	Output, Input, Interrupt
D8	GPIO15	Can't have pullup (only pulldown DIO)	Output
RX	GPIO3	Not usable during Serial transmission	Output, Input, Interrupt (if serial not used)
TX	GPIO1	Not usable during Serial transmission, Don’t connect to ground at boot time	Output, Input, Interrupt (if serial not used)
A0	ADC0	Analog	Not usable as DIO
SD3	GPIO10	Might be connected to flashmemory!!!	Not usable
SD2	GPIO9	Might be connected to flashmemory!!!	Not usable
SD1	MOSI		Unknown
CMD	CS		Unknown
SDO	MISO		Unknown
CLK	SCLK		Unknown
EN	Enable	DigitalWrite/Read not possible	Not usable
RST	Reset	DigitalWrite/Read not possible	Not usable

Don't use TX and it's alive

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