def _res(self, addr): ow = OneWire(Pin(self.pin)) ow.reset() ow.select_rom(addr) ow.writebyte(0x4E) if self.res == 12: ow.writebyte(0x7F) ow.writebyte(0x7F) ow.writebyte(0x7F) print("12 bit mode") if self.res == 11: ow.writebyte(0x5F) ow.writebyte(0x5F) ow.writebyte(0x5F) print("11 bit mode") if self.res == 10: ow.writebyte(0x3F) ow.writebyte(0x3F) ow.writebyte(0x3F) print("10 bit mode") if self.res == 9: ow.writebyte(0x1F) ow.writebyte(0x1F) ow.writebyte(0x1F) print("9 bit mode") ow.reset()
class TemperatureSensor: class _Const: CONVERT = const(0x44) RD_SCRATCH = const(0xbe) def __init__(self, pin): self._onewire = OneWire(pin) self._buffer = bytearray(9) self._rom = [rom for rom in self._onewire.scan() if rom[0] in (0x10, 0x22, 0x28)][0] self._convert_temp() def _convert_temp(self): self._onewire.reset(True) self._onewire.writebyte(self._onewire.SKIP_ROM) self._onewire.writebyte(self._Const.CONVERT) def _read_scratch(self): self._onewire.reset(True) self._onewire.select_rom(self._rom) self._onewire.writebyte(TemperatureSensor._Const.RD_SCRATCH) self._onewire.readinto(self._buffer) if self._onewire.crc8(self._buffer): raise Exception('Temperature sensor::CRC error') return self._buffer def read(self): buffer = self._read_scratch() if self._rom[0] == 0x10: if self._buffer[1]: t = self._buffer[0] >> 1 | 0x80 t = -((~t + 1) & 0xff) else: t = self._buffer[0] >> 1 return t - 0.25 + (self._buffer[7] - self._buffer[6]) / self._buffer[7] else: t = self._buffer[1] << 8 | self._buffer[0] if t & 0x8000: t = -((t ^ 0xffff) + 1) return t / 16
def _request(self, addr): _res(self, addr) ow = OneWire(Pin(self.pin)) ow.reset() ow.select_rom(addr) ow.writebyte(0x44) # command to take reading if self.res == 12: # the resolution determines the amount of time needed time.sleep_ms(1000) if self.res == 11: time.sleep_ms(400) if self.res == 10: time.sleep_ms(200) if self.res == 9: time.sleep_ms(100) ow.reset() # reset required for data ow.select_rom(addr) ow.writebyte(0xBE) # command to send temperature data # all nine bytes must be read LSB = ow.readbyte() # least significant byte MSB = ow.readbyte() # most significant byte ow.readbyte() ow.readbyte() ow.readbyte() # this is the configuration byte for resolution ow.readbyte() ow.readbyte() ow.readbyte() ow.readbyte() ow.reset() # reset at end of data transmission # convert response to binary, format the binary string, and perform math d_LSB = float(0) d_MSB = float(0) count = 0 b = bin(LSB) b2 = bin(MSB) b3 = "" l = 10 - len(b2) for i in range(l): if len(b2) < 10: b3 += "0" b2 = b3 + b2 b4 = "" l = 10 - len(b) for i in range(l): if len(b) < 10: b4 += "0" b5 = b4 + b for i in b5: if count == 2: if i == '1': d_LSB += 2**3 if count == 3: if i == '1': d_LSB += 2**2 if count == 4: if i == '1': d_LSB += 2**1 if count == 5: if i == '1': d_LSB += 2**0 if count == 6: if i == '1': d_LSB += 2**-1 if count == 7: if i == '1': d_LSB += 2**-2 if count == 8: if i == '1': d_LSB += 2**-3 if count == 9: if i == '1': d_LSB += 2**-4 count += 1 count = 0 sign = 1 for i in b2: if count == 6: if i == '1': sign = -1 if count == 7: if i == '1': d_MSB += 2**6 if count == 8: if i == '1': d_MSB += 2**5 if count == 9: if i == '1': d_MSB += 2**4 count += 1 temp = (d_LSB + d_MSB) * sign if self.unit == 'c' or self.unit == 'C': print("TEMP is: " + str(temp) + " degrees C") if self.unit == 'f' or self.unit == 'F': temp = (temp * 9 / 5) + 32 print("TEMP F is: " + str(temp)) return temp
class DS18X20(object): def __init__(self, pin): self.ow = OneWire(pin) # Scan the 1-wire devices, but only keep those which have the # correct # first byte in their rom for a DS18x20 device. self.roms = [rom for rom in self.ow.scan() if rom[0] == 0x10 or rom[0] == 0x28] def _select_rom(self, rom): if rom: self.ow.select_rom(rom) else: self.ow.skip_rom() def read_temp(self, rom=None): """ Read and return the temperature of one DS18x20 device. Pass the 8-byte bytes object with the ROM of the specific device you want to read. If only one DS18x20 device is attached to the bus you may omit the rom parameter. """ ow = self.ow ow.reset() self._select_rom(rom) ow.write_byte(0x44) # Convert Temp while True: if ow.read_bit(): break ow.reset() self._select_rom(rom) ow.write_byte(0xbe) # Read scratch data = ow.read_bytes(9) return self.convert_temp(rom[0], data) def read_temps(self): """ Read and return the temperatures of all attached DS18x20 devices. """ temps = [] for rom in self.roms: temps.append(self.read_temp(rom)) return temps def convert_temp(self, rom0, data): """ Convert the raw temperature data into degrees celsius and return as a float. """ temp_lsb = data[0] temp_msb = data[1] if rom0 == 0x10: if temp_msb != 0: # convert negative number temp_read = temp_lsb >> 1 | 0x80 # truncate bit 0 by shifting, fill high bit with 1. temp_read = -((~temp_read + 1) & 0xff) # now convert from two's complement else: temp_read = temp_lsb >> 1 # truncate bit 0 by shifting count_remain = data[6] count_per_c = data[7] temp = temp_read - 0.25 + (count_per_c - count_remain) / count_per_c return temp elif rom0 == 0x28: return (temp_msb << 8 | temp_lsb) / 16 else: assert False