ir_rx/nec.py

   1 # nec.py Decoder for IR remote control using synchronous code
   2 # Supports NEC and Samsung protocols.
   3 # With thanks to J.E. Tannenbaum for information re Samsung protocol
   4
   5 # For a remote using NEC see https://www.adafruit.com/products/389
   6
   7 # Author: Peter Hinch
   8 # Copyright Peter Hinch 2020-2022 Released under the MIT license
   9
  10 from utime import ticks_us, ticks_diff
  11 from ir_rx import IR_RX
  12
  13 class NEC_ABC(IR_RX):
  14     def __init__(self, pin, extended, samsung, callback, *args):
  15         # Block lasts <= 80ms (extended mode) and has 68 edges
  16         super().__init__(pin, 68, 80, callback, *args)
  17         self._extended = extended
  18         self._addr = 0
  19         self._leader = 2500 if samsung else 4000  # 4.5ms for Samsung else 9ms
  20
  21     def decode(self, _):
  22         try:
  23             if self.edge > 68:
  24                 raise RuntimeError(self.OVERRUN)
  25             width = ticks_diff(self._times[1], self._times[0])
  26             if width < self._leader:  # 9ms leading mark for all valid data
  27                 raise RuntimeError(self.BADSTART)
  28             width = ticks_diff(self._times[2], self._times[1])
  29             if width > 3000:  # 4.5ms space for normal data
  30                 if self.edge < 68:  # Haven't received the correct number of edges
  31                     raise RuntimeError(self.BADBLOCK)
  32                 # Time spaces only (marks are always 562.5µs)
  33                 # Space is 1.6875ms (1) or 562.5µs (0)
  34                 # Skip last bit which is always 1
  35                 val = 0
  36                 for edge in range(3, 68 - 2, 2):
  37                     val >>= 1
  38                     if ticks_diff(self._times[edge + 1], self._times[edge]) > 1120:
  39                         val |= 0x80000000
  40             elif width > 1700: # 2.5ms space for a repeat code. Should have exactly 4 edges.
  41                 raise RuntimeError(self.REPEAT if self.edge == 4 else self.BADREP)  # Treat REPEAT as error.
  42             else:
  43                 raise RuntimeError(self.BADSTART)
  44             addr = val & 0xff  # 8 bit addr
  45             cmd = (val >> 16) & 0xff
  46             if cmd != (val >> 24) ^ 0xff:
  47                 raise RuntimeError(self.BADDATA)
  48             if addr != ((val >> 8) ^ 0xff) & 0xff:  # 8 bit addr doesn't match check
  49                 if not self._extended:
  50                     raise RuntimeError(self.BADADDR)
  51                 addr |= val & 0xff00  # pass assumed 16 bit address to callback
  52             self._addr = addr
  53         except RuntimeError as e:
  54             cmd = e.args[0]
  55             addr = self._addr if cmd == self.REPEAT else 0  # REPEAT uses last address
  56         # Set up for new data burst and run user callback
  57         self.do_callback(cmd, addr, 0, self.REPEAT)
  58
  59 class NEC_8(NEC_ABC):
  60     def __init__(self, pin, callback, *args):
  61         super().__init__(pin, False, False, callback, *args)
  62
  63 class NEC_16(NEC_ABC):
  64     def __init__(self, pin, callback, *args):
  65         super().__init__(pin, True, False, callback, *args)
  66
  67 class SAMSUNG(NEC_ABC):
  68     def __init__(self, pin, callback, *args):
  69         super().__init__(pin, True, True, callback, *args)