circuitpython/docs/esp8266/tutorial/onewire.rst

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Controlling 1-wire devices
==========================
The 1-wire bus is a serial bus that uses just a single wire for communication
(in addition to wires for ground and power). The DS18B20 temperature sensor
is a very popular 1-wire device, and here we show how to use the onewire module
to read from such a device.
For the following code to work you need to have at least one DS18S20 or DS18B20 temperature
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sensor with its data line connected to GPIO12. You must also power the sensors
and connect a 4.7k Ohm resistor between the data pin and the power pin. ::
import time
import machine
import onewire, ds18x20
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# the device is on GPIO12
dat = machine.Pin(12)
# create the onewire object
ds = ds18x20.DS18X20(onewire.OneWire(dat))
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# scan for devices on the bus
roms = ds.scan()
print('found devices:', roms)
# loop 10 times and print all temperatures
for i in range(10):
print('temperatures:', end=' ')
ds.convert_temp()
time.sleep_ms(750)
for rom in roms:
print(ds.read_temp(rom), end=' ')
print()
Note that you must execute the ``convert_temp()`` function to initiate a
temperature reading, then wait at least 750ms before reading the value.