I’d like to drive the following stepper controller with the imp:
The stepper requires more than 3.3 volts so I’d like to power the stepper controller using a separate supply from an AC-based transformer. So can I have a mixed circuit where the imp is powered by the standard 5V USB wall wart, and the stepper controller is powered by a different supply, and they share a common ground? It’s the common ground that has me concerned since I recall there is a possibility of a potential difference between the grounds.
Yes, I know I could hang a voltage regulator off the higher voltage supply but I don’t have one handy and am trying to keep the circuitry a little simpler.
all supplies must have their grounds connected. also, the driver needs a logic supply voltage.
The board you picked has several options for it.
It is important to keep in mind that logic powerd from 5V does not always detect 3.3V as ‘high’. so in this case, you need to run the chips logic at 3.3V too. you can either remove SJ1 from the stepper board, or leave it in place and close SJ2 to set the logic suply to 3.3V
Also, if for example your usb wall wart would be 7V+, keep in mind that VIN-GND = 7v.