sensor gpio

[hannibal1986]

I have the temperature sensor DS18B20 connected to port 20 of the gpio as w1, if I want to connect another sensor it is as easy as adding a w2 and its port in /boot/bin/orangepiplus2e.bin

[w1_para]
w1_used = 1
gpio = 20

[w2_para]
w2_used = 1
gpio = 10

 

or

 

[w1_para]
w1_used = 1
gpio = 20

gpio = 10

 

So or something else? thanks

[martinayotte]

OneWire support multiple sensors on a single bus, so, there is no needs to have a second bus, simply place sensors in parallel ...

 

[hannibal1986]

parallel? in the same gpio pin? thanks

[martinayotte]

Yes ! OneWire is using UniqueID, so sensors won't answer to "discovery" function call at the same time, avoiding slave's answers collisions.

[Blars]

Onewire does have limitations on bus capacitance and length.  When using multiple sensors on one interface, it is best to not have stubs, wire to one sensor then the next rather than both from the pi.  You are also more likely to need to power your sensors rather than have them just on the bus.

 

[zador.blood.stained]

...but the 3.4.x legacy kernel has a limitation - you won't be able to instantiate more than one 1-wire bus without patching and recompiling the kernel.

Linear or star topology, not using parasite power, pull-up resistor value are details that would need to be adjusted for better reliability or even to make things work to start with.

I would recommend reading this application note: https://www.maximintegrated.com/en/app-notes/index.mvp/id/148

[hannibal1986]

thanks