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
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()
