Audio Passthrought code for ezDSP

Hi Abhishek,

We have provided Audio Filtering code for the EZDSP at the following site, the link for the code is towards the bottom of the page.

http://code.google.com/p/c5505-ezdsp/

Here is a description of what the code does:

This program takes audio input through I2S interface, then send back to I2S again.
Between intput and output:
FIR filter for 10 seconds (LED tunred on)
No filter for 10 seconds (LED turned off)

1) I2S interface
- Audio Codec: ADS3204 (Master/Slave)
- C5505 (Slave/Master)
- Sampling rate: 48KHz

2) Data
- Use Pingpong buffer  (two L inputs, two R inputs, two L outs, two R outs): total 8 buffers
- Buffer size: 48*2 words (16bit)

3) Filter
- FIR filter
- Fc = 2KHz
- -80dB@ 10KHz
- -1dB@1KHz

Best regards, Vishal

Hi Vishal,

Thanks for your reply. I downloaded the passthrough code and it is working fine. I want to change the ADC and DAC sampling rates from 48 KHz to 192 KHz. How to do this ?

Thanks,

Abhishek Seth.

Hi Abhishek Seth,

Please get the datasheet of the AIC3204 form this link: http://focus.ti.com/lit/ds/symlink/tlv320aic3204.pdf  You should be able to see registers that you need to modify for sampling rate change.

In the audio demo code, "aic_test_i2c.asm" file has the configuraitons for the audio codec, for example:

        AC1 = #1
        AR1 = #0x1
        call i2c_WriteData8

The first line is register address. The Second line is a value you want to write to the register. Basically, you are writing "1" to the register "0x01".

Thanks,

Peter Chung

i'm getting a warning when i build.

Severity and Description    Path    Resource    Location    Creation Time    Id
entry-point symbol other than "_c_int00" specified:  "reset_isr"        EZDSP_AudioFilter    line 0    1258497226487    3

i'm new at evaluating TI dsp, so i'm not sure if this is a good or a bad thing. any help?

-drb.

Hi David,

You are OK with this warning. By default, CCS is expecting the _c_int00 in the C Run Time Support Library (RTS) as the extry point. This example uses the reset_isr as the entry point instead. That is why the CCS gives the warning.

Ming