Quadrature encoder input

[ozindfw]

Before I dig into the source, has anyone done this yet? I want to be able to use a cheap encoder with a switch as a selection device.

Oz (in DFW)

[zranger1]

I do more software than hardware, but as far as I know, nobody has done anything like this. It would be helpful to know your application – do you want to use a rotary switch to choose patterns, or are you using the quadrature encoder to monitor some other device?

For use within a pattern, you could hook the output of your encoder to a couple of GPIO pins and make decisions in the pattern code based on that. Switching patterns via hardware might be harder.

Current Pixelblazes have a button attached to GPIO0 that, if pressed momentarily, increments the pattern and if pressed longer resets the Pixelblaze. To run through the patterns in one direction, you could replace that button with another controller, but I’m not aware of a hardware method for moving backwards through the list.

There’s good information on hardware switching in this thread:

Sensor Expansion board - use switches to change patterns?

Hi Frank! First, I just want to see if I understand what you want to do correctly. Do you want to use a combination of multiple external switches (or remote-controlled relays) to set which pattern is active (e.g. the state of 4 switches selecting one of 16 patterns)? Or was it that there are 4 independent sensors/switches/events and when any is activated, it should advance the pattern to the next one? Or were you saying you want to wire up a switch to advance through 4 different patterns, but t…

[wizard]

Hi @ozindfw,

You are the first that I know of

The best quadrature encoder systems on microcontrollers I’ve seen use either dedicated peripherals or GPIO interrupts to detect edge level changes. Unfortunately, these aren’t supported, and there isn’t first class encoder support.

You can poll the GPIO pin states in beforeRender() and with a small state machine decode the signals, but if you rotate it too fast compared to the frame rate, it can miss transitions.