Software issue with DAC MCP4921

[alex20]

Hello everyone.

I am using a PIC16F886 with a DAC MCP4921 SPI. I work in assembly language.
I cannot get the DAC to give voltage on its output pin. I have correctly assigned all other pins : the clock, the data in (for MCP, which is data OUT for PIC), the CS/SS, the ground, the power, and the refference.
Using an oscilloscope I succesfully managed to view all the signals on the DAC's pins. The problem is that I have absolutely nothing (no voltage) on the output pin.
As an algorithm for the DAC subroutine, I did this :

-configured all registers (sspcon)
-give a word (8 bytes) to the SSPBUF (buffer register)
-check if buffer full (if not, check again)
-give another word (8 bytes)
-check if buffer full (if not, check again)

I have also tried to load a dummy word (0x00 or 0xff) before loading the actual data to SSPBUF but with no result.

Can anyone give me some advice? Has anyone got a subroutine for DAC communication?

Thank you in advance,
alex

[petar.timotijevic]

Hi,

Please see

DAC click - Example - Board features 12-bit Digital-to-Analog Converter MCP4921 that features SPI interface and an optional double buffered output
http://www.libstock.com/projects/view/2 ... ck-example


Best regards,
Peter