Marlin 2.0.X > Setting output pins as open collector

Hi All,

I am about to finish a port of Marlin to Alfawise U20, and I have still a small problem.

Heater control pins are driving mosfets, and I need to have an open collector output pin on the STM32 CPU.

Is there any specific Marlin way of setting a pin as Open drain / Open collector? Or we have to dive in the code for that?

Please advise.

not that I have seen..

only thing close is the macros

#define SET_INPUT(IO) _SET_MODE(IO, INPUT) /*!< Input Floating Mode */
#define SET_INPUT_PULLUP(IO) _SET_MODE(IO, INPUT_PULLUP) /*!< Input with Pull-up activation */
#define SET_INPUT_PULLDOWN(IO) _SET_MODE(IO, INPUT_PULLDOWN) /*!< Input with Pull-down activation */
#define SET_OUTPUT(IO) OUT_WRITE(IO, LOW)
#define SET_PWM(IO) pinMode(IO, PWM)

So easy enough to add your own but using OUTPUT_OPEN_DRAIN or PWM_OPEN_DRAIN

You could use an NPN (or N-channel MOSFET - better still) to provide open collector from any CPU output if need be.

Scuse the quick and messy drawing ..