can SPI and I2C devices co-exist on the same pins?

bart.dinger · Joined: 02 Nov 2005 Posts: 9

Does anybody know if you can have SPI and I2C devices connected at the same time? For whatever design reason the mchip devices always share the SPI and I2C pins, but I can't find anywhere that says you have to exclusively use one or the other.

I figure the SPI devices will be fine with I2C data on their pins since they won't have their CS lines enabled, but what happens to an I2C device when there is SPI data flapping around on its bus? I wouldn't think anything would happen since a proper start/stop condition will never be met. Anybody ever tried this?

This all comes about because of a design/firmware upgrade that needs to backwards compatible with an older version Crying or Very sad

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Read these threads for comments about doing it:
http://www.ccsinfo.com/forum/viewtopic.php?t=970
http://www.ccsinfo.com/forum/viewtopic.php?t=18731
http://www.ccsinfo.com/forum/viewtopic.php?t=18793
http://www.ccsinfo.com/forum/viewtopic.php?t=20424

Here is a thread on the Microchip forum:
http://forum.microchip.com/tm.aspx?m=205782

Related threads:
http://www.ccsinfo.com/forum/viewtopic.php?t=17075
http://www.ccsinfo.com/forum/viewtopic.php?t=25138

Guest · Posted: Tue Apr 17, 2007 12:18 pm

THanks. I should have searched Embarassed

in here obviously.