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[FAQ] TLV320AIC3254: How and when can the C-RAM and I-RAM of the TLV320AIC3254 miniDSP be accessed?

Part Number: TLV320AIC3254

Can you provide more information regarding how and when can the C-RAM and I-RAM of the TLV320AIC3254 miniDSP be accessed?

  • I. When a miniDSP is powered off:

    Its C-RAM (or coefficient memory) can be accessed by the control bus. The miniDSP does not have access to C-RAM.

    Its I-RAM (or instruction memory) can be accessed by the control bus. The miniDSP does not have access to I-RAM.

    II. When a miniDSP is powered up (non-adaptive mode):

    Its C-RAM can be accessed by the miniDSP. The control bus does not have access to C-RAM (reading the registers return 0x00).

    Its I-RAM can be accessed by the miniDSP. The control bus does not have access to I-RAM (reading the registers return 0x00).

    III. When a miniDSP is powered up (adaptive mode):

    One of the C-RAM buffers can be accessed by the miniDSP. The control bus has access to the other C-RAM buffer.

    Its I-RAM can be accessed by the miniDSP. The control bus does not have access to I-RAM (reading the registers return 0x00).

    Applying a software or hardware /RESET clears C-RAM to default and resets all other registers. I-RAM remains as programmed until power is removed.Having said the above, C-RAM is shared with both miniDSP and PRB modes. I-RAM is unrelated to the PRB modes and only applies to miniDSP mode. The user can program I-RAM beforehand, use PRB mode and then switch to miniDSP mode. However, the DACs and ADCs must be powered off before switching.Additionally, C-RAM should be programmed each time with the correct data according to each mode (PRB or miniDSP). A software reset will set C-RAM coefficients automatically for PRB modes.

    For more details on C-RAM access refer to: http://www.ti.com/lit/pdf/slaa425