Serial control of a digital pot?

[TonyA]

Hi,

I am searching for info and examples for controlling a digital pot serially using shiftout. I am using the pic18f452, and I'm not sure which digital pot to use. Any suggestions/info would be greatly appreciated.

Thank you,
TonyA

[mister_e]

those i already used in the past from Microchip
MCP42010, MCP42050,MCP42100, MCP41010,MCP41050,MCP4110.

[TonyA]

Hi,

Are there any examples of code around?

Thanks,
Tony

[mister_e]

Not where i am, but i could download the datasheet and try something somewhere today.

As i remind it wasn't too complicated. Maybe there's some example here already done. Do a search with the model i suggest, you may find something

[TonyA]

I appreciate that very much. I will try a search here.

Thanks again,
Tony

[mister_e]

O.K it's untested but it should work for any MCP4XXXX digital pot. Try it and post your results

    '
    '    Hardware configuration
    '    ======================
    TRISC=0
    
    '                      
    '    Hardware connection
    '    ===================
    CS          VAR PORTC.0
    CLK         VAR PORTC.1
    SI          VAR PORTC.2
    
    '   
    '    Variables definition 
    '    ===================
    Wiper       var byte
    
    '
    '    Constants definition 
    '    ====================
    MSBFIRST    CON 1              
    WriteOnPot0 con %00010001

    '
    '    Software/Hardware initialisation
    '    ================================
    cs = 1      ' disable MCP
    PAUSE 100   ' safe settle time
    
Start:
    for wiper = 0 to 255
        cs=0                                            ' enable 
        shiftout si,clk, MSBFIRST,[WriteOnPot0, WIPER]  ' Write to MCP
        cs = 1                                          ' Disable
        pause 10                                       
        next                                           
    goto start

Now connect PA0 too vcc, PB0 to GND and read the voltage on PW0 pin... is this working?