6 Replies Latest reply on Sep 10, 2014 3:57 AM by hugo.elias

    Edge triggered DMA losing first byte

    hugo.elias

       I want to create an SPI component which leaves a small gap between bytes. To achieve this, I am using edge triggered DMA to transfer bytes to the SPI component. A PWM component is used to create the edges. I can vary the PWM period to vary the inter-byte spacing.

         

       

         

      It all works, except that the first byte is always missing! When I try to transfer the following bytes: {1,2,3,4,5,6,7,8} I see {2,3,4,5,6,7,8} come from the SPI component.

         

       

         

      When I was using the usual level triggered DMA, I never saw this problem.  What am I doing wrong? Please see attached waveform.

         

       

         

      Many thanks

         

      Hugo