Rotary encoder

[nui_de]

Hi,

wondering if somebody already has written a routine for wipy to work with a rotary encoder
and likes to share it

[nui_de]

Here is my adapted version for wipy.
Original Code thanks to Christopher Arndt.

Code: Select all

# -*- coding: utf-8 -*-
"""MicroPython rotary encoder library."""

from machine import Pin


ENC_STATES = (0, -1, 1, 0, 1, 0, 0, -1, -1, 0, 0, 1, 0, 1, -1, 0)


class Encoder(object):
    def __init__(self, pin_x = 'GP4',pin_y = 'GP5', pin_mode=Pin.PULL_UP,
                 scale=1,min=0, max=100, reverse=False):
        self.pin_x = (pin_x if isinstance(pin_x, Pin) else
                      Pin(pin_x, mode = Pin.IN, pull = pin_mode))
        self.pin_y = (pin_y if isinstance(pin_y, Pin) else
                      Pin(pin_y, mode = Pin.IN, pull = pin_mode))

        self.pin_mode = pin_mode
        self.scale = scale
        self.min = min
        self.max = max
        self.reverse = 1 if reverse else -1

        # The following variables are assigned to in the interrupt callback,
        # so we have to allocate them here.
        self._pos = -1
        self._readings = 0
        self._state = 0

        self.set_callbacks(self._callback)

    def _callback(self, line):
        self._readings = (self._readings << 2 | self.pin_x.value() << 1 |
                          self.pin_y.value()) & 0x0f

        self._state = ENC_STATES[self._readings] * self.reverse
        if self._state:
            self._pos = min(max(self.min, self._pos + self._state), self.max)

    def set_callbacks(self, callback=None):        
        self.irq_x = self.pin_x.irq(trigger = Pin.IRQ_FALLING | Pin.IRQ_RISING, handler = callback)
        self.irq_y = self.pin_y.irq(trigger = Pin.IRQ_FALLING | Pin.IRQ_RISING, handler = callback)

    @property
    def position(self):
        return self._pos * self.scale

    def reset(self):
        self._pos = 0
 

corrected typo thanks to pythoncoder

[pythoncoder]

Before Encoder Mode was supported on the Pyboard I posted some code here http://forum.micropython.org/viewtopic. ... =368#p1999 which could easily be adapted for the WiPy. The advantage is that it uses every transition on the X and Y signals and therefore offers higher resolution.

Incidentally I think your Pin.IRQ_RAISING is a typo.

[nui_de]

Pin.IRQ_RISING_FALLING is not supported by the wipy - so I used Pin.IRQ_RAISING
or what should it be?

[pythoncoder]

The docs say "The values can be ORed together, for instance mode=Pin.IRQ_FALLING | Pin.IRQ_RISING" - see http://docs.micropython.org/en/latest/w ... e.Pin.html. This indicates that you can interrupt on every edge. Note that, according to the docs, it's IRQ_RISING not IRQ_RAISING.

I'm basing this on reading the friendly manual - I haven't actually tried it on the WiPy.

[nui_de]

yep - thank you, I have read the manual but missed that statement and of course its "RISING"
Looked fine to me as I wrote it down and I got no Error with "RAISING".

[kfricke]

yep - thank you, I have read the manual but missed that statement and of course its "RISING"
Looked fine to me as I wrote it down and I got no Error with "RAISING".

This is an example of why post editing is to be prohibited in some cases. After you altering your typo in the initial post, Pythoncoders response seems to be stupid. Please at least comment your edit accordingly!

[nui_de]

I don't think that the respons seems to be stupid after you read my reply - the fact that there was a typo.
When you see any source in a posting you don't want to read the complete tread (okay, easy in this case)
to find out that this code does not work - just my opinion.

However I added a line in my posting to clearify that I corrected the mistake.