[quote:98d6d14975="mmarlette"]Will a DMA transfer increase the data transfer rate?[/quote:98d6d14975]
You're still limited to fper/2 = 16MHz SPI clock, but you can have DMA transferring the block of data.
Otherwise you've only 16 cpu clocks to fetch the actual data byte and put it into the SPI data register for transfer, which would mean (in case you want to have a steady SPI stream) that's not allowed to interrupt the cpu, which would then likely take longer than these 16 cycles.
Conclusion is then, if done [b:98d6d14975]without[/b:98d6d14975] DMA, the cpu needs to spend 100 percent of its time [b:98d6d14975]within[/b:98d6d14975] the loop to fill the SPI data register. With DMA you can try to refill the data sent out by the SPI, but even then you have only 16 clocks for refilling one byte.
And that's quite a task. All that said relates to an SPI clock of "only" peripheral clock divided by two.
If this clock would be (theoretically) even higher, how would you like to provide all that data?
↧
