For my next build I need to drive 4 NEMA23 in parallel mode as Z-stepppers.
Therefore I will use 4x Wantai DQ542MA Stepper drivers.
These driver have opto-coupler inputs and will need about 20mA to drive them.
The GPIO pins will be configured as "open drain"
In parallel connection I would need about ~80mA to drive the steppers
In series connection I would need only ~20mA to drive them.
What is the max current the GPIO pins can supply?
In the data-sheet for the LPC I could find
1.) I-latch current in the data sheet specified @ 100mA
but I also found
2.)I OHS HIGH-level short-circuit output current @ -45mA
3.)I OLS LOW-level short-circuit output current @ 50mA
I guess the last 2, are the values I need to know.
I guess that also means it will never exceed those currents, regardless of what is connected, right? (current limited outputs?)
If the max. current is only ~45/50mA, I will connect the drivers opto-coupler diodes in series connection and supply Vcc @12V using a 470Ohm resistor to limit the current at ~20mA. ( this will be the safest, I guess)
If the max. current is 100mA then parallel connecting the opto-couplers, supplying Vcc @5V to the drivers , should be OK.
thanks for helping