1 Reply Latest reply on Nov 16, 2011 11:34 PM by gautam.das.g

    Direct Memory Access in PSoC®3 and PSoC®5

    gautam.das.g

      PSoC®3 and PSoC®5 devices feature a Direct Memory Access (DMA) engine, which can used for data transfer between on-chip elements without any CPU intervention. The DMA engine is part of a high performance bus known as the peripheral hub (PHUB). The PHUB is a programmable and configurable central bus backbone within PSoC3/PSoC5 devices that ties the various on-chip system elements together. It consists of multiple spokes; each spoke is connected to one or more peripheral blocks.

         

      The DMA with the help of Transaction Descriptors (TD) can move data from a source to destination at very high speeds. The TDs can be chained together to perform complex data transfers. The following diagram illustrates a simple data transfer using DMA.

         

       

         

      The key features of PSoC® 3 and PSoC® 5 DMA are:

         
            
      • 24 DMA channels
      •     
      • Each channel has one or more Transaction Descriptors (TDs) to configure channel behavior. Up to 128 total TDs can be defined
      •     
      • TDs can be dynamically updated
      •     
      • Eight levels of priority per channel
      •     
      • Any digitally routable signal, the CPU, or another DMA channel, can trigger a transaction
      •     
      • Each channel can generate up to two interrupts per transfer
      •     
      • Transactions can be stalled or canceled
      •     
      • Supports transaction size of infinite or 1 to 64k bytes
      •     
      • TDs may be nested and/or chained for complex transactions
      •    
         

      Please refer AN52705 - PSoC® 3 and PSoC 5 - Getting Started with DMA for information on different ways to configure the DMA channel and TD to perform data transfers. The application note also has example projects and a brief video.