help using SHIFTOUT to control SPI digital potentiometer

[mark_s]

I believe you need to send a command byte before your data. I have never used this chip,
but have used a MCP42010. The digi-pot needs to know if you are reading or writing to it. Look at page 47 data sheet it is showing a 16bit command/data format.
It would probably be easy to send two bytes in a row while the CS line is low. First byte would be your
command byte and second your 8bit variable. Even if its only seven bits you need to send a zero to pad the 8th bit etc

PORTC.0 = 0
SHIFTOUT PORTC.1, PORTC.2, 1, [constant\8]
 SHIFTOUT PORTC.1, PORTC.2, 1, [variable\8]
 PORTC.0 = 1

 PAUSE 100

Here is an example sending two bytes, no need for bits
http://www.picbasic.co.uk/forum/show...light=MCP42010

or like this

PORTC.0 = 0
SHIFTOUT PORTC.1, PORTC.2, 1, [constant,variable]

 PORTC.0 = 1

 PAUSE 100

[keithv]

Thank you so much, Mark! That did the trick!

[mark_s]

Great!

What did you use for your control byte? In case someone else wants to use that chip in the future.