DS18x20 -> ds.convert_temp() Question

[Armen]

Hello PyLovers

Can anyone describe me about

ds.convert_temp() module ?

Code: Select all

# https://github.com/micropython/micropython/blob/master/drivers/onewire/ds18x20.py

_CONVERT = const(0x44)
def convert_temp(self):
        self.ow.reset(True)
        self.ow.writebyte(self.ow.SKIP_ROM)
        self.ow.writebyte(_CONVERT)

What happen if I don't use it in this sample?

Code: Select all

import time, ds18x20
ds = ds18x20.DS18X20(ow)
roms = ds.scan()
ds.convert_temp()
time.sleep_ms(750)
for rom in roms:
    print(ds.read_temp(rom))

# http://docs.micropython.org/en/latest/esp8266/quickref.html

Thanks
Armen

[fe2o3]

That's fine. convert_temp() is for when there is only ONE 1-wire temperature device
on the bus. Notice the SKIP_ROM command? It doesn't address any particular device.
Using it when there are multiple devices will cause some confusion.

[kevinkk525]

AFAIK convert_temp() instructs all ds18 on the bus to start the temperature conversion and is need before attempting to read from any sensor. But you don't need to call it before reading every single sensor, just before you start to read all sensors.