ir_tx/nec.py

   1 # nec.py Encoder for IR remote control using synchronous code
   2 # NEC protocol.
   3
   4 # Author: Peter Hinch
   5 # Copyright Peter Hinch 2020 Released under the MIT license
   6
   7 from micropython import const
   8 from ir_tx import IR, STOP
   9
  10 _TBURST = const(563)
  11 _T_ONE = const(1687)
  12
  13 class NEC(IR):
  14
  15     def __init__(self, pin, freq=38000, verbose=False):  # NEC specifies 38KHz
  16         super().__init__(pin, freq, 68, 33, verbose)  # Measured duty ratio 33%
  17
  18     def _bit(self, b):
  19         self.append(_TBURST, _T_ONE if b else _TBURST)
  20
  21     def tx(self, addr, data, _):  # Ignore toggle
  22         self.append(9000, 4500)
  23         if addr < 256:  # Short address: append complement
  24             addr |= ((addr ^ 0xff) << 8)
  25         for _ in range(16):
  26             self._bit(addr & 1)
  27             addr >>= 1
  28         data |= ((data ^ 0xff) << 8)
  29         for _ in range(16):
  30             self._bit(data & 1)
  31             data >>= 1
  32         self.append(_TBURST)
  33
  34     def repeat(self):
  35         self.aptr = 0
  36         self.append(9000, 2250, _TBURST)
  37         self.trigger()  # Initiate physical transmission.