IMPLEMENTED SO FAR

- Support for 4x20 LCD Display and large number display
- Brightness and contrast adjustment with remote
- (OPUS/Wolfson WM8741) DAC volume control: remote and rotary encoder
- (OPUS/Wolfson WM8741) DAC random filter selection 1 to 5 with remote
- (OPUS/Wolfson WM8741) DAC upsampling selection (L, M, H -this is the OSR setting)
- I2C level shifting (5V to 3.3V)
- Optimized power-up sequence

Thursday, June 25, 2009

Asynchronous Re-clocker vs Asynchronous Rate Converter

The same discussion thread teaches the theory behind sample rate conversion.

We should first distinguish between two terms that are often used interchangeably in audio circles but are completely different technologies:

Asynchronous re-clocking

Asynchronous re-clocking or re-sampling: this term describes a pretty simple operation where a digital audio signal is simply re-clocked by a clock from a different time base. There is no interpolation or rate conversion performed on the signal.

Asynchronous Sample Rate Conversion:

This is categorically different, in the sense that SIGNIFICANT interpolation is performed on the Fs_in (input sample rate) signal to minimize error (both time & freq domain) when the ultimate decimation to Fs_out (output sample rate) occurs. Example chips that can perform this function are the CS8420, AD1896 (and their brethren)...

...and the SRC4192 which is the subject of the next project.

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