SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The procedure in Table 24-345 initializes a McASP serializer n receiver(s) to operate in TDM-mode (the only mode supported by McASP receivers) after a power-on reset (POR). This is used for I2S (2-slot TDM) and other TDM-based audio protocols reception.
Before performing McASP global initialization, If external clock ACLKR is used, it must be running already for proper synchronization of the MCASP_GBLCTL register.
The McASP receivers support only TDM-frames (including 384-TDM frames) reception. DIT-frames reception (i.e. S/PDIF stream) can be implemented indirectly via an external DIR-chip converter with DIT-input and TDM (I2S)-compatible output connected to device McASP receiver input (TDM-only compatible).
Step | Register/Bit Field/Programming Model | Value |
---|---|---|
1. Apply software reset to different McASP receive components. | MCASP_GBLCTL[4:0] | 0x00 |
2. Poll the bits to ensure the active reset value (0x00) is successfully latched into the register. | MCASP_GBLCTL[4:0] | =0x00 |
3. Configure the local power management. | PWRIDLESYSCONFIG[1:0] IDLE_MODE | 0x1 |
4. Configure the receive format unit. | See Section 24.6.5.1.2.2.1. | |
5. Configure the receive frame sync generator. | See Section 24.6.5.1.2.2.2. | |
6. Configure the receive clock generator. | See Section 24.6.5.1.2.2.3. | |
7. Program all bits -RTDMSk (where k=0 to 31) according to the time slot characteristics desired (positions of active versus inactive slots within a frame). | MCASP_RXTDM [ k ] RTDMSk , where k=0 to 31 | 0x- |
8. Configure the desired n-th serializer for receive mode operation. (4) | MCASP_XRSRCTLn [1:0] SRMOD | 0x2 |
9. Configure the McASP pins functionality. | See Section 24.6.5.1.2.2.4. | |
10. Optional: Configure a McASP Rx channel for a loopback operation (TDM mode only) in MCASP_LBCTL [31:0]. | See Section 24.6.4.14.1, Loopback Mode Configurations. | 0x-(5) |
11. Release from reset state the divider that outputs the AHCLKR clock.(1) See also (2). | MCASP_GBLCTL[1] RHCLKRST | 0x1 |
12. Poll the bit to ensure that it is successfully latched in the register. See also (2). | MCASP_GBLCTL[1] RHCLKRST | =0x1 |
13. Release from reset state the divider that outputs the ACLKR clock. (1) See also (3). | MCASP_GBLCTL[0] RCLKRST | 0x1 |
14. Poll the bit to ensure that it is successfully latched in the register. See also (3). | MCASP_GBLCTL[0] RCLKRST | =0x1 |