Hi,
What can cause my signals to not possibly be strong enough? Faulty board?
No, I don't think its a faulty board, and I think its close enough to work as intended, we would know for sure one way
or another if you would only measure the current!
These are from the PoKeys 57CNC manual, I assume you have it?
On page 16 is the listing of the pin types in the motor output header, note all three outputs are of type DO_5.
On page 18 is a representative circuit of the DO_5 type output. The signal originates in the MCU and is buffered, that is the triangular symbol,
the current passes through the 100 Ohm resistor. PoKeys have put the resistor in the circuit to protect the buffer IC. If you accidentally shorted the
output to ground the current would be limited to about 50mA, probably just low enough that the IC doesn't fry up!
The downside is that if the output has to either source or sink any current the output voltage will suffer. With zero or near zero current from the output
the voltage of the pin will be 4.5V to 5V when high and 0.5V to 0V when low ie full TTL voltage swing. If the output is required to source/sink 10mA then the high voltage
will be reduced to 3.5V - 4.0V and the low voltage will increase to 1.5V - 1.0V. That is to say that the overcurrent protection resistor is now affecting the voltage swing of the output
so much that its borderline for TTL output.
Note that PoKeys determined that the output voltage swing is still acceptable if the input has to source/sink 8 mA.
Your stepper driver inputs require 10mA to switch so your PoKeys is borderline to drive the signals into the stepper driver. This is why I want you
to measure the current. Its going to be touch and go whether it will work without some modification. I think it will work but we absolutely NEED TO MEASURE
THE INPUT CURRENT TO THE DRIVER INPUTS.
If you cant do it yourself find someone who can.
If it turns out that the current is not enough don't panic we can fix that with a amplifier or MOSFET...easy. Still I think that the combination should work as is
if only you would knuckle down and make the required measurement.
Craig