tommi
Posts: 2
Joined: Fri Dec 28, 2012 9:44 pm

Using the old 6-channel 1-wire hub

Fri Dec 28, 2012 9:50 pm

Here's a short tutorial about how to put that old Hobby Boards 6-channel 1-wire master hub (the one with the serial cable) to work with your Raspberry Pi: https://sites.google.com/site/raspberry1wire/

repton
Posts: 91
Joined: Sat Mar 17, 2012 6:06 pm
Location: North Yorkshire, UK.
Contact: Website

Re: Using the old 6-channel 1-wire hub

Sat Dec 29, 2012 11:04 am

Nice site and thanks for taking the time to detail your process but I am slightly concerned about some of the detail in it, for example:
Because the Raspberry already uses TTL level signals, we don't need the level shifter anymore.
I believe the RasPi uses 3.3V signals for the GPIO UART port and not TTL. Whilst I'm not surprised that the DS2480B IC is happily receiving the 3.3V signal from the RasPi and working properly with it, I am slightly surprised that the 5V signal back from the DS2480B to your RasPi hasn't done some damage. I would perhaps consider using a couple of resistors as a voltage divider to reduce the 5V down to 3V3 to protect the RasPi.

I would also recommend not running digitemp as root using sudo. In order to allow a normal user to access the serial port and therefore use digitemp without needing sudo, simply add that user to the group "tty". To do this for user pi run this command:

sudo usermod -G tty pi

HTH,
Paul
UK Supplier of 1-Wire components, kits and modules:
http://www.sheepwalkelectronics.co.uk/

tommi
Posts: 2
Joined: Fri Dec 28, 2012 9:44 pm

Re: Using the old 6-channel 1-wire hub

Sun Dec 30, 2012 10:40 pm

Thanks for your most important remark!

It seems I forgot to RTFM for the Raspberry. In fact, I didn't even cross my mind that the Raspberry could use something else than TTL signals. The Raspberry does use 3.3 volt signals!

I will immediatelly correct my tutorial so no-one fries his Raspberry because of this. Somehow my Raspberry seems to have survived the abuse, but I'm about to fix it too.

And the other advice about not running digitemp as root is good too!

sroof
Posts: 13
Joined: Sun Jan 12, 2014 2:10 am

Re: Using the old 6-channel 1-wire hub

Sun Jan 12, 2014 2:26 am

I'm looking at options for connecting 8 or 10 DS18B20 1-wire sensors to my Pi. Your post about modifying the 6-channel HobbyBoards Hub is potentially useful (I have that Hub), but one question: Could the Hub just be connected to the Pi's USB port using a suitable USB-Serial adapter?

Any suggestions for setting up a network of DS18B20 sensors is welcome. However, all my sensors are already permanently wired in the parasitic power mode.
Thanks!

sroof
Posts: 13
Joined: Sun Jan 12, 2014 2:10 am

Re: Using the old 6-channel 1-wire hub

Tue Jan 14, 2014 2:48 pm

Well, I've answered my own question.
I connected my old Hobby Boards 6-channel 1-wire hub (with hard-wired DB-9 serial cable) to a USB-Serial adapter (one with a FTDI Chipset) attached my Pi. Using Digitemp, I am able to read my existing network of 13 DS18S20 sensors!

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