ir_rx/__init__.py

   1 # ir_rx __init__.py Decoder for IR remote control using synchronous code
   2 # IR_RX abstract base class for IR receivers.
   3
   4 # Author: Peter Hinch
   5 # Copyright Peter Hinch 2020 Released under the MIT license
   6
   7 from machine import Timer, Pin
   8 from array import array
   9 from utime import ticks_us
  10
  11 # Save RAM
  12 # from micropython import alloc_emergency_exception_buf
  13 # alloc_emergency_exception_buf(100)
  14
  15
  16 # On 1st edge start a block timer. While the timer is running, record the time
  17 # of each edge. When the timer times out decode the data. Duration must exceed
  18 # the worst case block transmission time, but be less than the interval between
  19 # a block start and a repeat code start (~108ms depending on protocol)
  20
  21 class IR_RX():
  22     # Result/error codes
  23     # Repeat button code
  24     REPEAT = -1
  25     # Error codes
  26     BADSTART = -2
  27     BADBLOCK = -3
  28     BADREP = -4
  29     OVERRUN = -5
  30     BADDATA = -6
  31     BADADDR = -7
  32
  33     def __init__(self, pin, nedges, tblock, callback, *args):  # Optional args for callback
  34         self._pin = pin
  35         self._nedges = nedges
  36         self._tblock = tblock
  37         self.callback = callback
  38         self.args = args
  39         self._errf = lambda _ : None
  40         self.verbose = False
  41
  42         self._times = array('i',  (0 for _ in range(nedges + 1)))  # +1 for overrun
  43         pin.irq(handler = self._cb_pin, trigger = (Pin.IRQ_FALLING | Pin.IRQ_RISING))
  44         self.edge = 0
  45         self.tim = Timer(-1)  # Sofware timer
  46         self.cb = self.decode
  47
  48     # Pin interrupt. Save time of each edge for later decode.
  49     def _cb_pin(self, line):
  50         t = ticks_us()
  51         # On overrun ignore pulses until software timer times out
  52         if self.edge <= self._nedges:  # Allow 1 extra pulse to record overrun
  53             if not self.edge:  # First edge received
  54                 self.tim.init(period=self._tblock , mode=Timer.ONE_SHOT, callback=self.cb)
  55             self._times[self.edge] = t
  56             self.edge += 1
  57
  58     def do_callback(self, cmd, addr, ext, thresh=0):
  59         self.edge = 0
  60         if cmd >= thresh:
  61             self.callback(cmd, addr, ext, *self.args)
  62         else:
  63             self._errf(cmd)
  64
  65     def error_function(self, func):
  66         self._errf = func
  67
  68     def close(self):
  69         self._pin.irq(handler = None)
  70         self.tim.deinit()