PicBasic Pro code to drive MCP4291 DAC?

[rmteo]

I don't know what the OP's application is but using a PIC and a serial DAC (MCP4921) to generate sine waves is extremely inefficient. It consumes a tremendous amount of CPU resources and gives very poor performance - limited frequency range and resolution. Using a DDS chip such as the AD8937 (which incidentally costs about the same as then MCP4921) allows you to generate sine (and triangle and square) waveforms from 0-16MHz with 0.06Hz (28-bit) resolution. For low frequency applications (such as VFDs) you can use a lower speed clock - with a 1MHz clock you get 0-1MHz and 0.004Hz resolution. It uses the same SPI interface as the MCP4921 and the slowest 4MHz PIC will still be able to generate up to a 16MHz sine wave.

[gadelhas]

I don't know what the OP's application is but using a PIC and a serial DAC (MCP4921) to generate sine waves is extremely inefficient. It consumes a tremendous amount of CPU resources and gives very poor performance - limited frequency range and resolution. Using a DDS chip such as the AD8937 (which incidentally costs about the same as then MCP4921) allows you to generate sine (and triangle and square) waveforms from 0-16MHz with 0.06Hz (28-bit) resolution. For low frequency applications (such as VFDs) you can use a lower speed clock - with a 1MHz clock you get 0-1MHz and 0.004Hz resolution. It uses the same SPI interface as the MCP4921 and the slowest 4MHz PIC will still be able to generate up to a 16MHz sine wave.

rmteo, isn't AD9837?

[rmteo]

Yes, it is AD9837. Sorry for the typo.

[gadelhas]

Very interesting chip....

[mark_s]

rmteo,
You are correct an spi dac is not suited for generating sine waves. My goal was to
learn how to use this dac, which I did. I have used the AD9835 and AD9850 which are lower
resolution versions of the AD9837, which you mentioned. The 28 bits of resolution is fantastic and
I may request a sample since Digikey and Mouser don't stock the AD9837 yet.

Regards