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9fba618356
The OneWire class is now in its own onewire.py module, and the temperature sensor class is in its own ds18x20.py module. The latter is renamed to DS18X20 to reflect the fact that it will support both the "S" and "B" variants of the device. These files are moved to the modules/ subdirectory to take advantage of frozen bytecode.
38 lines
1008 B
Python
38 lines
1008 B
Python
# DS18x20 temperature sensor driver for MicroPython.
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# MIT license; Copyright (c) 2016 Damien P. George
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_CONVERT = const(0x44)
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_RD_SCRATCH = const(0xbe)
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_WR_SCRATCH = const(0x4e)
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class DS18X20:
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def __init__(self, onewire):
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self.ow = onewire
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def scan(self):
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return [rom for rom in self.ow.scan() if rom[0] == 0x28]
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def convert_temp(self):
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self.ow.reset(True)
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self.ow.writebyte(self.ow.SKIP_ROM)
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self.ow.writebyte(_CONVERT)
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def read_scratch(self, rom):
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self.ow.reset(True)
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self.ow.select_rom(rom)
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self.ow.writebyte(_RD_SCRATCH)
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buf = self.ow.read(9)
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if self.ow.crc8(buf):
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raise Exception('CRC error')
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return buf
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def write_scratch(self, rom, buf):
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self.ow.reset(True)
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self.ow.select_rom(rom)
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self.ow.writebyte(_WR_SCRATCH)
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self.ow.write(buf)
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def read_temp(self, rom):
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buf = self.read_scratch(rom)
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return (buf[1] << 8 | buf[0]) / 16
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