AnsweredAssumed Answered

Simultaneous DMAs: Poor docs or restrictive hardware?

Question asked by fisher.burns on Oct 19, 2012
Latest reply on Oct 19, 2012 by fisher.burns
The STM32L1xx reference manual has this text in the DMA section:
       
  1.    

    The 7 requests from the peripherals (TIMx[2,3,4,6,7], ADC1, SPI[1,2], I2Cx[1,2],    USARTx[1,2,3]) and DAC Channelx[1,2] are simply logically ORed before entering the DMA,    this means that only one request must be enabled at a time. Refer to Figure 25: DMA    request mapping

       

Can someone help me understand what this means?  It sounds like it is saying that only a single peripheral can have DMA enabled at any one time.  That seems like a terrible restriction.  It makes more sense that only one peripheral that is directed to a particular DMA channel can be enabled at once.  And the figure cited shows 7 OR gates, 1 for each channel.  That makes more sense, but it is not what the text says!  Can someone confirm that the 'sensible' meaning is true?

Thanks...

Outcomes