The McASP time-division multiplexed (TDM) transfer mode supports the TDM format discussed in Section 24.6.2.2.3.
Transmitting data in the TDM transfer mode requires a minimum set of pins:
- ACLKX - transmit bit clock
- AFSX - transmit frame sync (or commonly called left/right clock)
- One or more serial data pins, AXRn, whose serializers are configured to transmit
For more details on McASP transmitting serializers clock and frame sync options, refer to the Section 24.6.4.2.1, Transmit Clock, and Section 24.6.4.2.3, Frame-Sync Generator .
Similarly, to receive data in the TDM transfer mode requires a minimum set of pins:
- ACLKR - receive bit clock
- AFSR - receive frame sync (or commonly called left/right clock)
- One or more serial data pins, AXRn, whose serializers are configured to receive
For more details on McASP receiving serializers clock and frame sync options, refer to Section 24.6.4.2.2, Receive Clock, and Section 24.6.4.2.3, Frame-Sync Generator .
The control registers must be configured as follows for the TDM mode. The TDM mode specific bit fields are highlighted in bold:
- MCASP_PFUNC: The clock, frame, data pins must be configured for McASP function.
- MCASP_PDIR: The clock, frame, data pins must be configured to the direction desired.
- MCASP_PDOUT, MCASP_PDIN, MCASP_PDSET, MCASP_PDCLR: Not applicable. Leave at default.
- MCASP_GBLCTL: Follow the initialization sequence is described in the Section 24.6.5.2, Operational Modes Configuration.
- MCASP_AMUTE: Leave this register at default state.
- MCASP_LBCTL: If loopback mode is desired, configure this register according to Section 24.6.4.14, otherwise leave this register at default.
- MCASP_TXDITCTL: DITEN must be left at default 0 to select TDM mode (transmitters only).
- MCASP_RXMASK/MCASP_TXMASK: Mask desired bits according to Section 24.6.4.4, Format Units.
- MCASP_RXFMT/MCASP_TXFMT: Program all fields according to data format desired. See the Section 24.6.4.4, Format Units.
- MCASP_RXFMCTL/MCASP_TXFMCTL: Set RMOD/XMOD bits to (0x2 - 0x20) for Rx/Tx (2- 32 slots) TDM mode. In addition, set RMOD to 0x180 if 384-slot TDM stream has to be received by McASP. Configure other fields as desired.
- MCASP_ACLKRCTL/MCASP_ACLKXCTL: Program all fields according to bit clock desired. For more inforamtion, refer to Section 24.6.4.2.
- MCASP_AHCLKRCTL/MCASP_AHCLKXCTL: Program all fields according to high-frequency clock desired. For more details, refer to Section 24.6.4.2.
- MCASP_RXTDM/MCASP_TXTDM: Program all fields according to the time slot characteristics desired.
- MCASP_EVTCTLX: Program all fields according to transmit interrupts desired.
- MCASP_RXCLKCHK/MCASP_TXCLKCHK: Program all fields according to clock checking desired.
- MCASP_XRSRCTLn: Program all fields according to serializer operation desired.