SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
When the McASP operates in DIT mode, the data transmitted is output as a biphase-mark encoded bitstream, with preamble, channel status, user data, validity, and parity automatically stuffed into the bitstream by the McASP. The McASP includes separate validity bits for even/odd subframes and two 384-bit RAM modules to hold channel status and user data bits.
The transmit TDM time slot register (MCASP_TXTDM) should be programmed to all 1s during DIT mode. TDM functionality is not supported in DIT mode, except that the TDM slot counter counts the DIT subframes.
To transmit data in DIT mode, the following pins are typically required:
For DIT Mode Transmission Data Alignment Settings see Section 26.6.4.4.1.2.
If the McASP is configured to transmit in the DIT mode on more than one serial data pin, the bit streams on all pins will be synchronized. In addition, although they will carry unique audio data, they will carry the same channel status, user data, and validity information.
The actual 24-bit audio data must always be in bit positions 23–0 after passing through the first three stages of the transmit format unit.