8 channel 1 wire expander + 1 wire temperature sensor

mrosas
Posts: 4
Joined: Tue Oct 13, 2015 12:23 pm

8 channel 1 wire expander + 1 wire temperature sensor

Postby mrosas » Tue Oct 13, 2015 12:57 pm

Hi,

I need 8 1wire temperature sensor in the unipi, but not simultaneously. When the user need the sensor, he will plug it in one of the free ports in the 8 channel expander. It's posible?

Also, can i plug 8 sensors in one expander?

Thanks

Regards

Mario
tomas_hora
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Re: 8 channel 1 wire expander + 1 wire temperature sensor

Postby tomas_hora » Wed Oct 14, 2015 9:31 am

Hello,

I do not understand what do you mean by 'not simultaneously'. You can put up to 10-20 sensors (depending on the cable length and electrical noise) right in the 1wire channel of UniPi without the expander just by using the 8port hubs.

If you need more than that thats when you should consider the 8channel expander where you could connect more than 8*(10 to 20) sensors.

Br,
Tomas
mrosas
Posts: 4
Joined: Tue Oct 13, 2015 12:23 pm

Re: 8 channel 1 wire expander + 1 wire temperature sensor

Postby mrosas » Wed Oct 14, 2015 10:08 pm

Hi Tomas,

For my project, the temperature sensors will be mobile, and i will not plug all sensors always, i want only the sensors 'active' at the time, but a maximum of the 8 sensors allowed by expander.

So, the expander will be empty, no sensor plugged at first time. I will detect the sensors when be plugged, and start the control of temperature.

When the temperature control is finished, this sensor will be removed from expander.

Thanks

Best regards

Mario
tomas_hora
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Re: 8 channel 1 wire expander + 1 wire temperature sensor

Postby tomas_hora » Thu Oct 15, 2015 7:53 am

Acutally you can use only 7 sensors per expander (or 6 if there are more expanders). See this http://unipi.technology/wiki/1Wire_topology
mrosas
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Joined: Tue Oct 13, 2015 12:23 pm

Re: 8 channel 1 wire expander + 1 wire temperature sensor

Postby mrosas » Thu Oct 15, 2015 9:01 am

The "8 Port HUB" and the expander have the same connection schema? What's the function of the 2 black connectors in the expander?

Perhaps there are some additional documentation about the expander but i don't see it.

Thanks
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jaroslav_sobota
Posts: 32
Joined: Tue Dec 02, 2014 1:16 pm

Re: 8 channel 1 wire expander + 1 wire temperature sensor

Postby jaroslav_sobota » Thu Oct 15, 2015 12:39 pm

The "8 Port HUB" is pure metal - just a connection box to make branches of the 1-Wire bus easily. All the communication with 1-Wire sensors is handled by the UniPi's onboard 1-Wire master (the DS2482-100 chip). There is only one 1-Wire bus.

On the contrary, the "8channel 1Wire expander" contains also some silicon (the DS2482-800 chip). This chip handles the 8 separate 1-Wire buses (those are the shiny connectors). Each one of them is equivalent to the 1-Wire port of the UniPi itself. The black connectors are meant for connecting the expander board to the UniPi via the I2C bus.
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mrosas
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Joined: Tue Oct 13, 2015 12:23 pm

Re: 8 channel 1 wire expander + 1 wire temperature sensor

Postby mrosas » Thu Oct 15, 2015 9:18 pm

Thanks for your reply.

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