SPRUHM9H October 2014 – May 2024 TMS320F28075 , TMS320F28075-Q1 , TMS320F28076
When using the DMA with the RX FIFO, the DMA Burst Size (BURST_SIZE) must be no greater than RXFFIL to prevent the DMA from reading from an empty FIFO. To make sure that the DMA correctly receives all data from the RX FIFO, the DMA Burst Size can equal RXFFIL and also be an integer divisor of the total number of SPI transmissions.
For complete data reception, follow these steps:
To receive 200 words from SPI using the DMA:
NUM_WORDS = 200
RXFFIL: 4
DMA_TRANSFER_SIZE: (NUM_WORDS /RXFFIL) – 1 = (200/4) – 1 = 49 (50 transfers)
DMA_BURST_SIZE = RXFFIL-1 = 3 (4 words per burst)