I have a TIC834 stepper motor controller (https://www.pololu.com/product/3133) which works great for my stepper motor. It's however a 5 V based system. And my stepper motor includes a 3.3 V limit switch where the limit switch output requires 10k ohm pull-up.
Now I want to interface this output to one of the TIC inputs. But it's not clear to me how I can do this. Some input pins on this model already have a pull-up to 5 V. See for example the RX and TX pins which can be configured as inputs (https://www.pololu.com/docs/0J71/all#4.5).
What is the easiest way for me to interface this 3.3 V output that requires a pull-up to the TIC board?
Any help is appreciated.
Best Answer
The 5V input might be able to still properly interpret a pull-up to 3.3V as a logic HI which would allow you to just pull up to 3.3V and connect directly.
There's also a chance that even the switch on your stepper motor, being open-drain might be able to tolerate being pulled to 5V despite it accepting 3.3V elsewhere. You would need to check the datasheet to be sure.
But if none of this works then you can do the following:
If you can live with an inverted output, you can have less circuitry.
simulate this circuit – Schematic created using CircuitLab
You can also just use a level translator or a logic buffer gate that takes a 5V supply and outputs 5V but whose logic high threshold interprets a 3.3V input as a logic HI.