read_code.py

   1 import utime
   2
   3
   4 def read_code(pin):
   5     raw = []
   6
   7     # Signal is inverted:
   8     # 0 - high signal
   9     # 1 - low signal
  10
  11     # wait for the leading pulse
  12     while pin.value() == 1:
  13         pass
  14
  15     # 9ms leading pulse
  16     # 4.5ms space
  17     utime.sleep_us(13500)
  18
  19     # Sample signal every 562.5µs
  20     # Time sensitive
  21     for i in range(1000):
  22         raw.append(pin.value())
  23         utime.sleep_us(56)
  24
  25     code = ""
  26     count = 0
  27
  28     for sample in raw:
  29         if sample == 1:
  30             # count low signal
  31             count += 1
  32         else:
  33             # ignore high signal
  34             if count > 0:
  35                 # if low signal is longer than 562.5µs it 1 otherwise 0
  36                 code += "1" if count > 10 else "0"
  37                 count = 0
  38
  39     # trim message transmission and repeat codes
  40     return code[0:32]