SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
To perform internal transfers through the configuration bus, set the XBUSEL/RBUSEL bit to 1 in the MCASP_TXFMT/MCASP_RXFMT registers, respectively. Failure to do so may result in software malfunction.
McASP1, McASP2, and McASP3, whose data ports are accessible directly via L3_MAIN do not support FIFO/constant addressing modes. Incrementing transfers must be used instead.
In this method, the DMA/CPU accesses the XRBUFn transmit or receive buffer through corresponding configuration bus (CFG) address.
The exact XRBUFn transmit/receive buffer physical address for any particular serializer is determined by adding the transmit/receive buffer alias register offset for that particular serializer to the base address of McASP CFG port actual for L4_PER2 accesses. The XRBUFn buffer of the n-th serializer configured as a transmitter is aliased - MCASP_TXBUFn in the CFG port address space. For example, the XRBUF2 transmit buffer is mapped as the MCASP_TXBUF2 register. Similarly, the XRBUFn buffer of the n-th serializer configured as a receiver is aliased - MCASP_RXBUFn in the CFG port address space. For example, the XRBUF3 receive buffer is mapped as the MCASP_RXBUF3 register.
Accessing the XRBUF through the DATA port (see Section 24.6.4.10.1.3 ) is different than CFG port accesses because the DATA port access demands the same physical address, regardless of transfer direction or current channel index , while accessing through the peripheral configuration port - CFG, the DMA/CPU must provide the exact MCASP_TXBUFn or MCASP_RXBUFn address upon accessing n-th serializer TX or RX buffer, respectively. For more details about MCASP_TXBUFn and MCASP_RXBUFn addresses corresponding to McASP CFG port, see Section 24.6.6.2.1, MCASP_CFG Register Summary.