Quote Originally Posted by Darrel Taylor
The datasheet for the MCP3221 is a bit ambiguous. While the graphic in figure 5-2 shows the device code as 1001. The text in section 5.2 says that it's 1010.
Tell me about the ambiguity! One of the reasons I aksed the question is that the AppNote (AN845) and the datasheet are confusing. My problems could stem from this.

Quote Originally Posted by Darrel Taylor
I've never used that part before, so I don't know which one it really is, but you might try ...

cont con %10101010
I'll give a few of these variants a go - worth a try for a small amount of effort.

Quote Originally Posted by Darrel Taylor
Also, the first byte sent (B1) is the highbyte. So the A/D value will have to be greater than 1280 (1.56V) to satisfy the B1 > 2 condition.
Exactly as it is meant to - I have a pot and reference voltage attached; I should be able to swap the lit LED by turning the pot (nice easy check).

Quote Originally Posted by Darrel Taylor
And, don't forget the pull-up resistors on SDA and SCL.<br><br>
Already fitted on the Pictail board - one of the advantages of using two of the Microchip development boards together is that the hardware is definitely correct - pity their software data is so ambiguous!

Many thanks Darrel - I was starting to question whether I had missed some other device specific code. It's nice to have some confirmation that it ma only be the address / control code. Can anyone else confirm the correct MCP3221 control/address byte?

Rod