Need help with TLV320AIC23 and C54

Started by kevin_agnew August 26, 2002
I have the above audio codec attached to a C54 using a MCBSP to
send/receive audio data. We have verified the timing on the
CLKX/CLKR, FSX/FSR, and DX/DR signals with an oscope and everything
matches the TLV320AIC23 spec. The AIC is programmed as MASTER so it
is driving CLKX/CLKR and FSX/FSR, while the C54 has been programmed
to use these as external signals. (Actually BCLK from the AIC is
connected to both CLKX/CLKR on the C54.)

I know that I am able to write the AIC control registers as I can put
it into and out of analog loopback mode, plus can vary the volume.

But I am unable to get it to generate audio data from my digital
data. We even tried outputting a constant digital value (0x8000)
just to see if we could raise the DC value of line out, but no

My assumption is that I'm programming one of the AIC registers
incorrectly (or else we blew the DAC!). The digital data I receive
from the AIC appears as though it is actual audio data, so the
receive path seems to be working. My AIC register settings are
listed below.

Any suggestions or help would be immensely appreciated! P.S - I'm
new to this group, but have been a TI DSP programmer (along with
various general purpose processors) for 16 years. I am however,
fairly new to programming the C54 (I've used C40, C6x, and C8x
primarily) and have never programmed a MCBSP or an audio codec.

AIC register settings for audio playback:

Left line volume (address 0x00): 0x117
Right line volume (address 0x01): 0x117
Analog audio path (address 0x04): 0x012
Digital audio path(address 0x05): 0x004
Power down control(address 0x06): 0x000
Digital format (address 0x07): 0x05f
Sample rate (address 0x08): 0x00c
Digital activation(address 0x09): 0x001

MCLK is running at 12.2727 MHz (video pixel clock), which is slightly
slower than the 12.288 MHz clock shown in the AIC's sampling rate
tables. We are using the sample rate setting for 8 KHz ADC and DAC.
With our slightly slow MCLK, we expect this to give us 7.99 KHz
sampling rate which is sufficient for our needs.

Thank you!!!

-- Kevin