I have a RasPi model B rev. 2.0 and two DS18B20 1-wire temperature sensors and they are working individually fine. I know I should be able to connect multiple 1-wire sensors in parallel but I can't detect any sensors when connecting more than one at the same time (to the same GPIO pin). Individually I can detect each sensor.
This is one of the sensors and the only one connected:
This is the other and the only one connected:
When I connect both in parallel it shows nothing under
I have connected my sensors to pin 7 (GPIO 7) which is the dedicated 1-wire pin.
As they work individually, I am pretty sure I am connecting it correctly:
- Red to
- Yellow to
- Black to
And when having multiple sensors I am just connecting both reds, both yellows and both blacks in to a terminal strip.
Is this my sensors being faulty or am I doing something wrong?
UPDATE #1, 2014-Dec-18, 22:42
I am using the built-in pull-up resistor in my Python programming and it has been suggested by @joan that I should try with a real 4.7K Ohm resistor instead as the built-in may be too weak to support multiple sensors.