Golbez
Posts: 1
Joined: Sat Aug 10, 2013 10:26 pm

Is there a limit for the amount...

Sat Aug 10, 2013 10:31 pm

I was wondering if there was a limit for the amount of max31855 thermocouples i am able to connect to my raspberry pi. i currently have 2 of them working, am interested in using 4 or maybe 6 in total.

-golbez

sprinkmeier
Posts: 410
Joined: Mon Feb 04, 2013 10:48 am
Contact: Website

Re: Is there a limit for the amount...

Wed Aug 14, 2013 12:48 am

https://en.wikipedia.org/wiki/Serial_Pe ... advantages
No in-band addressing; out-of-band chip select signals are required on shared buses
As long as your SPI bus stays withing spec, and you have some way of selecting the sensor you want to talk to, you should e able to use as many as you want.

I've run 16 DS1820's off a single serial port using a simple little adapter and a bit-banging driver.
I've used 5V DIO pins as well (arduino), not sure how you'd go with the 3.3V GPIO pins on the Pi.
These might scale a bit better than SPI with chip-select.

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