CCS: TMS570LC3137 - Question about Sci with DMA act

1. About trigger

  - Hardware Trigger : This trigger automatically, when DMA is enabled or SADD is set?

QJ> Yes, DMA module is enable, and SCI DMA functionality is enabled too (SET TX DMA, and SET RX DMA)

  - Software Trigger : I want to know this action. And it is possible to control the trigger timing when i want ?

QJ>DMA supports both HW request and SW request. The transfer will be triggered by writing to SW Channel Enable Set and Status Register. You can enable this bit whenever you want.

2. DMA enable/disable Each channel.

  - I want to use just one channel(receive sci/transfer sci) . I want to know it is possible to use DMA as follows.

(1) Receive state : enable DMA receive sci / disable DMA transfer sci

(2) Transfer state : disable DMA receive sci / enable DMA transfer sci

QJ>Yes, you can use one channel for both TX and RX. But you need reconfig the packets and request line mapping. I'd like to use one channel for TX and another channel for RX.

Hello Minwoo,

The hardware request can trigger either a frame or a block transfer depending on your setting of TTYPE bit in CHCTRL register.

I assume that in your settings the element size is 1 byte and frame size is 100 elements, and block size is 20 frames. If you use frame transfer, after 1 frame (100 bytes) is transferred, the DMA request (HW or SW) is required to start the next  frame (100 bytes) transfer. It won't star automatically.

But if you use block transfer, the 2nd frame will be transferred automatically after the 1st frame is transferred. The DMA request (HW or SW) is not required.