Duet3 MBHC GPIO (input on output and vice versa)

pfn

I'm running out of IO ports, is there any way to use an output pin on the IO0-8 ports as an input or vice versa? To clarify, the question is more along the lines of what features are supported on which pins? Which of the IO pins capable of ADC? Which are capable of PWM? etc.

Thanks!

dc42

@pfn this is documented at https://duet3d.dozuki.com/Wiki/Duet_3_Mainboard_6HC_Hardware_Overview#Section_IO.

pfn

@dc42 so, to be clear, there is no capability for doing in on an out pin or vice versa?

peter247

@pfn Strange I was going to ask the same question .

on the duet 5 mini you have 7 inputs to use for triggers and end stops , which 1 is shared with the display.
So x , y , z end stops take 3 inputs , that leaves 1 filament run out and 2 triggers.

Phaedrux

@pfn said in Duet3 MBHC GPIO (input on output and vice versa):

@dc42 so, to be clear, there is no capability for doing in on an out pin or vice versa?

I don't understand the question. The IO ports have both in and out pins, do you want 2 in pins on a single IO port? Why would you need to go in on an out pin?

peter247

@phaedrux I think what he is asking is that he as spare output pins can he turn them to input pins. ( and vice versa)

pfn

@peter247 precisely, I've run out of output pins actually, it would be good if I could re-use in pins as out.

dc42

@pfn said in Duet3 MBHC GPIO (input on output and vice versa):

@dc42 so, to be clear, there is no capability for doing in on an out pin or vice versa?

The IN pins have 10K protection resistors in series with them, so you would need to bypass that to use them as outputs. It should be possible to use the OUT pins as inputs on the MB6HC.

pfn

@dc42 Thanks for the clarity!

pfn

@dc42 I forgot to ask before. To what voltage levels are the OUTs safe if used as IN? 3.3v? 5v?

Thank you!

T3P3Tony

@pfn the outputs only have 470R series resistors so only use 3.3V

dc42

@pfn the output pins have no protection diodes and only a 470R series resistor, so 3.3V only.

pfn

I'm finally getting around to using an out pin as an input. Like follows for my X end stop:

M574 X1 S1 P"io7.out"

However, when I do this, it seems like there's a delay before the endstop signal is recognized, if I home at full speed, the motor stalls for a little bit before it stops and re-probes the endstop. If I slow down homing, it stalls less.

It seems like there's a delay in signal processing/polling on the out pins. Is there something that can be done to change this?

dc42

@pfn if the endtop is a simple 2 wire switch then you will need to either enable the pullup resistor in the M574 command or add an external pullup resistor.

pfn

@dc42 oh duh! It totally slipped my mind. Thank you!