16F630 and MCP3221 I2C

[Darrel Taylor]

badcock,

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.

I've never used that part before, so I don't know which one it really is, but you might try ...

cont con %10101010

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.

And, don't forget the pull-up resistors on SDA and SCL.<br><br>

[badcock]

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.

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.

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).

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

[badcock]

I just tracked some information down on the Microchip website:

Description: Section 5.2 of the datasheet states '1010' is the 4-bit device code.
However, all of the diagrams indicate '1001' is the device code.
Which is it?

Resolution: The paragraph is incorrect.
The device code is '1001' as stated in the diagrams.

I'll give the other code a try!

Rod

[badcock]

I just tracked some information down on the Microchip website:


I'll give the other code a try!

Rod

But the code I had originally used was correct - could there be something else I am missing?

Rod

[Darrel Taylor]

Rod,

Your comments show that the LED's are on PORTA.0 and PORTA.1

But, PORTA.1 and PORTA.2 are being toggled after reading the ADC<br><br>

[badcock]

Rod,

Your comments show that the LED's are on PORTA.0 and PORTA.1

But, PORTA.1 and PORTA.2 are being toggled after reading the ADC<br><br>

Not a problem - 16F630 is in the PicKit1 board - there are LEDS on RA1, RA2, RA4 and RA5. My comments are incorrect!

Rod

[Darrel Taylor]

Is there a jumper installed in JP1 on the PICtail board?

It connects the pot to the ADC.<br><br>