SPRUIV7B May 2022 – September 2023 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP
The procedure in Table 12-18 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 (this is, 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. | MCASP_PWRIDLESYSCONFIG[1-0] IDLE_MODE | 0x1 |
4. Configure the receive format unit. | See Section 12.1.1.5.1.2.2.1. | |
5. Configure the receive frame sync generator. | See Section 12.1.1.5.1.2.2.2. | |
6. Configure the receive clock generator. | See Section 12.1.1.5.1.2.2.3. | |
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_RTDM[k] RTDMSk , where k = 0 to 31 | 0x- |
8. Configure the desired n-th serializer for receive mode operation.(4) | MCASP_SRCTLn [1-0] SRMOD; n = 0 to 15 | 0x2 |
9. Configure the MCASP pins functionality. | See Section 12.1.1.5.1.2.2.4. | |
10. Optional: Configure a MCASP Rx channel for a loopback operation (TDM mode only) in MCASP_DLBCTL [31-0]. | See Section 12.1.1.4.14.1, 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 |