SCI DMA Interface
1245
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Serial Communication Interface (SCI)/ Local Interconnect Network (LIN)
Module
25.4 SCI DMA Interface
DMA requests for receive (RXDMA request) and transmit (TXDMA request) are available for the SCI/LIN
module. The DMA transfers depending on whether multi-buffer mode bit (MBUF MODE in the SCIGCR1
register) is enabled or is not enabled. See
for additional information.
25.4.1 Receive DMA Requests
This DMA functionality is enabled/disabled by the CPU using the SET RX DMA/CLR RX DMA bits,
respectively.
In Multi-Buffered SCI mode with DMA enabled, the receiver loads the RDy buffers for each received
character. RX DMA request is triggered once the last character of the programmed number of characters
(LENGTH) are received and copied to the corresponding RDy buffer successfully.
If the multi-buffer option is disabled, then DMA requests will be generated on a byte-per-byte basis.
In multiprocessor mode, the SCI can generate receiver interrupts for address frames and DMA requests
for data frames or DMA requests for both. This is controlled by the SET RX DMA ALL bit.
In multiprocessor mode with the SLEEP bit set, no DMA is generated for received data frames. The
software must clear the SLEEP bit before data frames can be received.
25.4.2 Transmit DMA Requests
DMA functionality is enabled/disabled by the CPU with SET TX DMA/CLR TX DMA bits, respectively.
In Multi-Buffered SCI mode, once the TXRDY bit is set or after a transmission of programmed number of
characters (LENGTH) (up to eight data bytes stored in the transmit buffer(s) TDy in the LINTD0 and
LINTD1 registers), a DMA request is generated in order to reload the transmit buffer for the next
transmission. If the multi-buffer option is disabled, then DMA requests will be generated on a byte-per-byte
basis.