Gear motor encoder gives no pulses: power, phases and pull-ups

The encoder has its own power pins. Check that it has the supply voltage, then watch A and B on a pin while you turn the shaft.

What the message means

A Hall encoder needs its own supply and gives two pulse signals. A missing supply or a wrong wire gives no pulses at all.

Fix it in this order

1. Check the encoder power and ground wires, and the voltage the encoder accepts.
2. Turn the shaft by hand and read A and B on two input pins.
3. Use INPUT_PULLUP, or add external pull-ups, where the outputs are open collector.
4. Use interrupt-capable pins when the speed is high.
5. Keep the encoder wires away from the motor wires.

If you see this, do this

Related

wrong encoder counts, interrupt variables.

Last reviewed: November 2026. These are the usual causes and the order that finds them fastest. Test on your own board; clones and cables differ.