Consecutive SPI Writes

[MONODA]

Hey I've working on a project which involves interfacing an IC which contains a DAC module via SPI. I'm using TI's TMS320F2807 DSP and am able to interface the DAC.

I want to write to the SPI interface as fast as possible but the SPI peripheral of the TMS320 keeps the /CS pin active between consecutive writes to the SPI channel and the DAC expects a rising edge on /CS between each write.

Any ideas as to how I can force this to occur?

Thanks

[duskglow]

Use another output pin and AND it with /CS?

[Harvs]

I had a similar problem with the STM32F0 using the DMA with a DAC that needed exactly what you've just described. 

The easiest answer was to use the DMA to do a single word write (it needed 24bits per write) then trigger a tuned interrupt routine to toggle a GPIO pin that was used for _CS.  The key was to just write this naked ISR in assembly, then it only took a few CPU cycles to write the set and reset GPIO registers with a literal, re-enable the DMA to do another 3Byte transfer and return.

[nctnico]

If the SPI interface has a buffer then you might as well use the interrupt routine to write all the data. Or set the word length longer (does it support 32 bit?).