us100.py

   1 import utime
   2
   3 class US100UART:
   4     """Read the US-100 sonar sensor in UART mode."""
   5
   6     def __init__(self, uart):
   7         self.uart = uart
   8         uart.init(baudrate=9600, bits=8, parity=None, stop=1)
   9         utime.sleep_ms(100)
  10         self.buf = bytearray(2)
  11         self.t = 0
  12
  13     def distance(self):
  14         """Read the temperature compensated distance im millimeters."""
  15         self.buf[0] = 0
  16         self.buf[1] = 0
  17         self.uart.write(b'\x55')
  18         self.t = utime.ticks_ms()
  19         while not self.uart.any():
  20             if utime.ticks_diff(utime.ticks_ms(), self.t) > 100:
  21                 raise Exception('Timeout while reading from US100 sensor!')
  22             utime.sleep_us(100)
  23         self.uart.readinto(self.buf, 2)
  24         return (self.buf[0] * 256) + self.buf[1]
  25
  26     def temperature(self):
  27         """Read the temperature in degree celcius."""
  28         self.buf[0] = 0
  29         self.uart.write(b'\x50')
  30         self.t = utime.ticks_ms()
  31         while not self.uart.any():
  32             if utime.ticks_diff(utime.ticks_ms(), self.t) > 100:
  33                 raise Exception('Timeout while reading from US100 sensor!')
  34             utime.sleep_us(100)
  35         self.uart.readinto(self.buf, 1)
  36         return self.buf[0] - 45