ir_tx/__init__.py

   1 # __init__.py Nonblocking IR blaster
   2 # Runs on Pyboard D or Pyboard 1.x (not Pyboard Lite) and ESP32
   3
   4 # Released under the MIT License (MIT). See LICENSE.
   5
   6 # Copyright (c) 2020 Peter Hinch
   7 from sys import platform
   8 ESP32 = platform == 'esp32'  # Loboris not supported owing to RMT
   9 if ESP32:
  10     from machine import Pin, PWM
  11     from esp32 import RMT
  12 else:
  13     from pyb import Pin, Timer  # Pyboard does not support machine.PWM
  14
  15 from micropython import const
  16 from array import array
  17 from time import ticks_us, ticks_diff
  18 # import micropython
  19 # micropython.alloc_emergency_exception_buf(100)
  20
  21 # On ESP32 gate hardware design is led_on = rmt and carrier
  22
  23 # Shared by NEC
  24 STOP = const(0)  # End of data
  25
  26 # IR abstract base class. Array holds periods in μs between toggling 36/38KHz
  27 # carrier on or off. Physical transmission occurs in an ISR context controlled
  28 # by timer 2 and timer 5. See TRANSMITTER.md for details of operation.
  29 class IR:
  30     _active_high = True  # Hardware turns IRLED on if pin goes high.
  31     _space = 0  # Duty ratio that causes IRLED to be off
  32     timeit = False  # Print timing info
  33
  34     @classmethod
  35     def active_low(cls):
  36         if ESP32:
  37             raise ValueError('Cannot set active low on ESP32')
  38         cls._active_high = False
  39         cls._space = 100
  40
  41     def __init__(self, pin, cfreq, asize, duty, verbose):
  42         if ESP32:
  43             self._pwm = PWM(pin[0])  # Continuous 36/38/40KHz carrier
  44             self._pwm.deinit()
  45             # ESP32: 0 <= duty <= 1023
  46             self._pwm.init(freq=cfreq, duty=round(duty * 10.23))
  47             self._rmt = RMT(0, pin=pin[1], clock_div=80)  # 1μs resolution
  48         else:  # Pyboard
  49             if not IR._active_high:
  50                 duty = 100 - duty
  51             tim = Timer(2, freq=cfreq)  # Timer 2/pin produces 36/38/40KHz carrier
  52             self._ch = tim.channel(1, Timer.PWM, pin=pin)
  53             self._ch.pulse_width_percent(self._space)  # Turn off IR LED
  54             # Pyboard: 0 <= pulse_width_percent <= 100
  55             self._duty = duty
  56             self._tim = Timer(5)  # Timer 5 controls carrier on/off times
  57         self._tcb = self._cb  # Pre-allocate
  58         self._arr = array('H', 0 for _ in range(asize))  # on/off times (μs)
  59         self._mva = memoryview(self._arr)
  60         # Subclass interface
  61         self.verbose = verbose
  62         self.carrier = False  # Notional carrier state while encoding biphase
  63         self.aptr = 0  # Index into array
  64
  65     def _cb(self, t):  # T5 callback, generate a carrier mark or space
  66         t.deinit()
  67         p = self.aptr
  68         v = self._arr[p]
  69         if v == STOP:
  70             self._ch.pulse_width_percent(self._space)  # Turn off IR LED.
  71             return
  72         self._ch.pulse_width_percent(self._space if p & 1 else self._duty)
  73         self._tim.init(prescaler=84, period=v, callback=self._tcb)
  74         self.aptr += 1
  75
  76     # Public interface
  77     # Before populating array, zero pointer, set notional carrier state (off).
  78     def transmit(self, addr, data, toggle=0, validate=False):  # NEC: toggle is unused
  79         t = ticks_us()
  80         if validate:
  81             if addr > self.valid[0] or addr < 0:
  82                 raise ValueError('Address out of range', addr)
  83             if data > self.valid[1] or data < 0:
  84                 raise ValueError('Data out of range', data)
  85             if toggle > self.valid[2] or toggle < 0:
  86                 raise ValueError('Toggle out of range', toggle)
  87         self.aptr = 0  # Inital conditions for tx: index into array
  88         self.carrier = False
  89         self.tx(addr, data, toggle)  # Subclass populates ._arr
  90         self.trigger()  # Initiate transmission
  91         if self.timeit:
  92             dt = ticks_diff(ticks_us(), t)
  93             print('Time = {}μs'.format(dt))
  94
  95     # Subclass interface
  96     def trigger(self):  # Used by NEC to initiate a repeat frame
  97         if ESP32:
  98             self._rmt.write_pulses(tuple(self._mva[0 : self.aptr]), start = 1)
  99         else:
 100             self.append(STOP)
 101             self.aptr = 0  # Reset pointer
 102             self._cb(self._tim)  # Initiate physical transmission.
 103
 104     def append(self, *times):  # Append one or more time peiods to ._arr
 105         for t in times:
 106             self._arr[self.aptr] = t
 107             self.aptr += 1
 108             self.carrier = not self.carrier  # Keep track of carrier state
 109             self.verbose and print('append', t, 'carrier', self.carrier)
 110
 111     def add(self, t):  # Increase last time value (for biphase)
 112         assert t > 0
 113         self.verbose and print('add', t)
 114         # .carrier unaffected
 115         self._arr[self.aptr - 1] += t
 116
 117
 118 # Given an iterable (e.g. list or tuple) of times, emit it as an IR stream.
 119 class Player(IR):
 120
 121     def __init__(self, pin, freq=38000, verbose=False):  # NEC specifies 38KHz
 122         super().__init__(pin, freq, 68, 33, verbose)  # Measured duty ratio 33%
 123
 124     def play(self, lst):
 125         for x, t in enumerate(lst):
 126             self._arr[x] = t
 127         self.aptr = x + 1
 128         self.trigger()