STM32F429 High speed DAC interupt + USART interrupt misses characters

[rinwinte]

Posted on November 13, 2014 at 06:54

To drive my application I use two DAC in a interrupt. The data sended to the DAC needs to count up and count down between two variable(bits) so that it creates a triangular wave. The maximum value is 4095. 

The frequency of the wave needs to be around 100Hz. To create the wave I use TIM2 interrupt.Sysclk = 180Mhz, Tim2Clk = 90Mhz. Interrupt frequency = 100Hz*(4096*2) = 819200 Hz.Problem is that because of the interrupt frquency is 820kHz (what is really high) the Usart interupt routine misses some characters.How can I solve this? The only thing i can come up with is to use DMA for the USART receiving. But better should be to cut the DAC loose from the CPU somehow.

[rinwinte]

Posted on November 13, 2014 at 12:23yes it is too high. I try to find me a solution to put it down by changing te code.

[Tesla DeLorean]

Posted on November 13, 2014 at 17:08

You could decimate the interrupt loading by using a small pattern buffer, and updating alternate pairs in the HT an TC DMA interrupts.

In the spirit of

http://en.wikipedia.org/wiki/Decimation_%28Roman_army%29

, you could have a 20 sample buffer (2 x 10), and update 10 samples at each 80 KHz interrupt instead of 1 @ 800 KHz