DAC Signal Generator stm32

Question

I am programming DAC peripheral of stm32f2xx. I have an array of bytes (Sound) & I would like to generate signal with sample rate = 8K.

Now my question is: How do I specify sample rate?

Note: I googled alot. I am only getting trangle wave generation and sine wave generation using DMA. I dont want to use DMA.

Thanks in advance for help... Regards,

Answer 1

It's not practical to play waveforms out of the DAC without using DMA. You set up the DMA with your samples, and you set up the DAC to use a timer as the trigger. Then you set up your timer to trigger at your desired sample rate.

Answer 2

I would agree with TJD that in general it is not practical to do so without DMA, however it is not impossible, particularly at a low sample rate.

One could use a timer set to trigger every 1/8000th of a second as the fixed time base. From there, the interrupt routine would need to load up the next sample into the DAC. The sample rate could be varied by changing the timer's time base.

It would be a similar effort to write the code to configure the DMA controller when compared to writing the code to move the correct sample into the buffer. However, the DMA approach would be more reliable, likely posses less jitter in the sample rate, and frees up the core to execute other code that may be needed. In fact, with the TIM/DMA/DACs setup, you may be able to halt the core or enter a sleep mode that keeps peripheral clocks running.

Answer 3

yes, i agree with TJD too.
using DMA is effecient as well as free up CPU for other task [good].
managing the timing in software(core with busy loop) [bad] will not produce good results. (so, use timer for timing [good]).
now for copying, you have to dedicate CPU to do the copying after a specific interval of time (from busy-loop or timer timeout) to DAC register.[bad]

at the end i recommend, connect DMA and timer, and on timeout, DMA will copy data to DAC register [good]. this solution only appear hard but actually much easier to work with when setup'd.
[note: written in pov of someone who is trying to understand/start on something like this]