Part Number: TMS320F28335
Other Parts Discussed in Thread: C2000WARE
Hi:
The demo code I used is "C2000Ware_1_00_03_00\device_support\f2833x\examples\mcbsp_loopback_dma". I just want to make sure:
1. The word size is 8-bit , I remeber that in Mcbsp SPI configuration, the word size could be 16-bit?
2.The init of DMA:
//
// Channel 1, McBSPA transmit
//
DmaRegs.CH1.BURST_SIZE.all = 0; // 1 word/burst
DmaRegs.CH1.SRC_BURST_STEP = 0; // no effect when using 1 word/burst
DmaRegs.CH1.DST_BURST_STEP = 0; // no effect when using 1 word/burst
//
// Interrupt every frame (128 bursts/transfer)
//
DmaRegs.CH1.TRANSFER_SIZE = 127;
//
// Move to next word in buffer after each word in a burst
//
DmaRegs.CH1.SRC_TRANSFER_STEP = 1;
DmaRegs.CH1.DST_TRANSFER_STEP = 0; // Don't move destination address
DmaRegs.CH1.SRC_ADDR_SHADOW = (Uint32) &sdata[0];
//
// Not needed unless using wrap function
//
DmaRegs.CH1.SRC_BEG_ADDR_SHADOW = (Uint32) &sdata[0];
//
// Start address = McBSPA DXR
//
DmaRegs.CH1.DST_ADDR_SHADOW = (Uint32) &McbspaRegs.DXR1.all; //目的地的首地址
//
// Not needed unless using wrap function
//
DmaRegs.CH1.DST_BEG_ADDR_SHADOW = (Uint32) &McbspaRegs.DXR1.all;
The configuration here is "DmaRegs.CH1.SRC_BURST_STEP = 0; // no effect when using 1 word/burst" .
In my mind, the source addr is this buffer "sdata". During the first burst transmission, the sorce addr should be sdata[0], then next burst transmisson should be sdata[1]. In this case, I think CH1.SRC_BURST_STEP should be 1 but not 0.
The "DmaRegs.CH1.DST_BURST_STEP = 0; // no effect when using 1 word/burst" is fine I think beacuese the DST addr is always DXRx reg.
Whether it just 1 word per burst, the src addr would be increased automatically by default, so I do not need change SRC_BURST_STEP?
