38 lines
1008 B
Python
38 lines
1008 B
Python
|
# DS18x20 temperature sensor driver for MicroPython.
|
||
|
|
# MIT license; Copyright (c) 2016 Damien P. George
|
||
|
|
|
||
|
|
_CONVERT = const(0x44)
|
||
|
|
_RD_SCRATCH = const(0xbe)
|
||
|
|
_WR_SCRATCH = const(0x4e)
|
||
|
|
|
||
|
|
class DS18X20:
|
||
|
|
def __init__(self, onewire):
|
||
|
|
self.ow = onewire
|
||
|
|
|
||
|
|
def scan(self):
|
||
|
|
return [rom for rom in self.ow.scan() if rom[0] == 0x28]
|
||
|
|
|
||
|
|
def convert_temp(self):
|
||
|
|
self.ow.reset(True)
|
||
|
|
self.ow.writebyte(self.ow.SKIP_ROM)
|
||
|
|
self.ow.writebyte(_CONVERT)
|
||
|
|
|
||
|
|
def read_scratch(self, rom):
|
||
|
|
self.ow.reset(True)
|
||
|
|
self.ow.select_rom(rom)
|
||
|
|
self.ow.writebyte(_RD_SCRATCH)
|
||
|
|
buf = self.ow.read(9)
|
||
|
|
if self.ow.crc8(buf):
|
||
|
|
raise Exception('CRC error')
|
||
|
|
return buf
|
||
|
|
|
||
|
|
def write_scratch(self, rom, buf):
|
||
|
|
self.ow.reset(True)
|
||
|
|
self.ow.select_rom(rom)
|
||
|
|
self.ow.writebyte(_WR_SCRATCH)
|
||
|
|
self.ow.write(buf)
|
||
|
|
|
||
|
|
def read_temp(self, rom):
|
||
|
|
buf = self.read_scratch(rom)
|
||
|
|
return (buf[1] << 8 | buf[0]) / 16
|