Hey folks! I'm building my own CNC Radial Axis machine, and I'm running into a bit of a snag. My CNC controller seems to operate at 3V, while my stepper driver requires a 5V input. I've been struggling to check the signals with my multimeter since it doesn't seem fast enough, and I don't have an oscilloscope to help out. Currently, I'm using a bi-directional logic shifter, but I'm worried it might not be up to the task. ChatGPT suggested I try a 74LS245 shifter instead, which is on its way, but I'm not completely confident this will solve the issue. Am I on the right track, or is there something else I should consider? I'm really invested in making this project work and would appreciate any guidance! Thanks a ton! - Ashes
3 Answers
Have you considered using a simple transistor switch? It could be a reliable way to shift signals from 3V to 5V if the timing's not too critical.
It sounds like you're really close! Just a heads up, the 74LS245 might not drive the 5V requirement fully. It's worth double-checking the exact voltage needs of your stepper driver; sometimes it can run on slightly less than 5V, which could work with something like a CMOS 245. Make sure to look at the datasheets to confirm!
Thanks for the tip! I'll make sure to check the datasheets when I get home.
For 5V TTL signals, remember there’s a 1.5V threshold for high signal. You could measure the voltage when nothing’s moving to get a better idea of the logic level. Also, checking the stepper board directly might help clarify the voltage it needs. If you see a voltage of only ~95mV on the pul/dir, it definitely seems low compared to the 5V requirement.
Good to know! I’ll check what I can on the stepper board to see if I can get more accurate readings.
I hadn't thought about that! Can you give me more details about what type of transistor switch I should look for?