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 2020-2022 Released under the MIT license
   6
   7 # With thanks to J.E. Tannenbaum for information re Samsung protocol
   8 from micropython import const
   9 from ir_tx import IR, STOP
  10
  11 _TBURST = const(563)
  12 _T_ONE = const(1687)
  13
  14 class NEC(IR):
  15     valid = (0xffff, 0xff, 0)  # Max addr, data, toggle
  16     samsung = False
  17
  18     def __init__(self, pin, freq=38000, verbose=False):  # NEC specifies 38KHz also Samsung
  19         super().__init__(pin, freq, 68, 33, verbose)  # Measured duty ratio 33%
  20
  21     def _bit(self, b):
  22         self.append(_TBURST, _T_ONE if b else _TBURST)
  23
  24     def tx(self, addr, data, _):  # Ignore toggle
  25         if self.samsung:
  26             self.append(4500, 4500)
  27         else:
  28             self.append(9000, 4500)
  29         if addr < 256:  # Short address: append complement
  30             if self.samsung:
  31               addr |= addr << 8
  32             else:
  33               addr |= ((addr ^ 0xff) << 8)
  34         for _ in range(16):
  35             self._bit(addr & 1)
  36             addr >>= 1
  37         data |= ((data ^ 0xff) << 8)
  38         for _ in range(16):
  39             self._bit(data & 1)
  40             data >>= 1
  41         self.append(_TBURST)
  42
  43     def repeat(self):
  44         self.aptr = 0
  45         self.append(9000, 2250, _TBURST)
  46         self.trigger()  # Initiate physical transmission.