Troubleshooting • Issues using a logic level converter driven by the Pi GPIO

Hey folks,

I'm stuck on something I thought would be simple. I am trying to use the GPIO on the PI to drive a stepper motor driver. Because the GPIO on the Pi sources 3.3V I am using a logic level converter to step the voltage up to 5V.

Without the stepper motor driver connected to the high side pins on the logic level converter the device is operating as expected. When I enable a GPIO pin to high (3.3V) the HV pin on the logic level converter goes to 5v.

However when I attach the HV pins on the logic level converter to the stepper motor driver and try to enable a GPIO pin my input voltage is pulled down to 2.3 volts and the output does not shift to 5 volts - instead is around 2.3 volts as well.

It appears as if the Pi cannot source enough current to run a logic level converter when that converter in turn is hooked up to a stepper motor driver - does this seem to make sense?

Schematic attached.

Any ideas?

Thanks!

Statistics: Posted by davef_dci — Tue Aug 27, 2024 8:46 pm — Replies 1 — Views 10

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