MCP41XXX SPI Write

[johnmiller]

Hi.
I cannot write a new value to a mcp41010 SPI Digital Potentiometer. What I'm trying to do is

WriteSPI:
    CS = 0                              ' Enable serial EEPROM
    Shiftout SI, SCK, MSBFIRST, [$06]   ' Send write enable command
    CS = 1                              ' Disable to execute command
    CS = 0                              ' Enable
    Shiftout SI, SCK, MSBFIRST, [$02, 0, 0, UpdPotVal]   ' Send address and data
    CS = 1                              ' Disable

    RETURN

UpdPotVal goes from 0 to 255

Can somebody please tell me what I am doing wrong. Here is a C code that does the same thing in case somebody knows how to make use of it!

#define CS PIN_B4
#define SCLK PIN_B2
#define SI PIN_B1

set_pot (int data) {
   BYTE i;
   BYTE cmd[2];

   cmd[0] = data;
   cmd[1] = 0x11;

   output_low(SCLK);
   output_low(CS);

   for(i=1;i<=16;++i) {
      output_bit(SI, shift_left(cmd,2,0));

      output_high(SCLK);
      output_low(SCLK);
   }
   output_high(CS);
}

shutdown_pot () {
   BYTE i;
   BYTE cmd[2];

   cmd[0] = 0;
   cmd[1] = 0x21;

   output_low(SCLK);
   output_low(CS);

   for(i=1;i<=16;++i) {
      output_bit(SI, shift_left(cmd,2,0));

      output_high(SCLK);
      output_low(SCLK);
   }
   output_high(CS);
}

Regards