drivers/onewire: Fix ds18x20.read_temp so it works when no rom given.
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@ -7,14 +7,13 @@ temperature sensors. It supports multiple devices on the same 1-wire bus.
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The following example assumes the ground of your DS18x20 is connected to
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Y11, vcc is connected to Y9 and the data pin is connected to Y10.
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>>> gnd = Pin('Y11')
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>>> gnd.init(Pin.OUT_PP)
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>>> from pyb import Pin
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>>> gnd = Pin('Y11', Pin.OUT_PP)
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>>> gnd.low()
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>>> vcc = Pin('Y9')
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>>> vcc.init(Pin.OUT_PP)
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>>> vcc = Pin('Y9', Pin.OUT_PP)
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>>> vcc.high()
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>>> from ds18x20 import DS18X20
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>>> d = DS18X20(Pin('Y10'))
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Call read_temps to read all sensors:
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@ -47,27 +46,22 @@ class DS18X20(object):
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# correct # first byte in their rom for a DS18x20 device.
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self.roms = [rom for rom in self.ow.scan() if rom[0] == 0x10 or rom[0] == 0x28]
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def _select_rom(self, rom):
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if rom:
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self.ow.select_rom(rom)
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else:
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self.ow.skip_rom()
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def read_temp(self, rom=None):
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"""
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Read and return the temperature of one DS18x20 device.
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Pass the 8-byte bytes object with the ROM of the specific device you want to read.
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If only one DS18x20 device is attached to the bus you may omit the rom parameter.
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"""
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rom = rom or self.roms[0]
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ow = self.ow
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ow.reset()
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self._select_rom(rom)
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ow.select_rom(rom)
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ow.write_byte(0x44) # Convert Temp
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while True:
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if ow.read_bit():
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break
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ow.reset()
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self._select_rom(rom)
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ow.select_rom(rom)
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ow.write_byte(0xbe) # Read scratch
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data = ow.read_bytes(9)
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return self.convert_temp(rom[0], data)
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