USB Audio 2.0 Reference Design
https://www.xmos.com/products/development-kits/usbaudio2
Some days ago I recieved my USB Audio 2.0 Card. Since I am running Windows, I couldn't just plug and play it as a soundcard. (Windows do no provide a driver for USB Audio Class 2.0 like Mac OS 10.6 or later yet. Maybe Win7 SP1 !?)
I recieved the source-code from XMOS, but the USB part was a little heavy to me to just read and understand. Instead I started from the beginning writing a main.xc that should just bypass the analog signal from Stereo-Line IN to Stereo-Line Out. Being a 'non programmer'; I'm very happy that I made it working just during this evening starting from scratch.
The picture shows the Blue inputsignal (sin^2) and the corresponding red output signal. The total delay is about 0.5 ms from In to Out @ 44.1 kHz as I written the code right now.
Click the link below to see the image
http://www.xmoslinkers.org/node/353
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More Fs
Today I tried to add support for the other samplingsfreqs, but my code does not run determenistic. It only works for 44.1 kHz, and for any higher freqs the digital intertransmission gets a lot of failures which can be easily seen in an eyeplot on the scope.
It's the chapter 5&6 in the manual, "Synchronising Clocked I/O on Multiple Ports" combined with "Serialising Output Data using a Port" that I do not get yet.
Several syncronised (buffered) serial ports running in the same thread at high data rates.
Moved to the XE-forum
I have moved my work to the XCore Exhange forum.
XMOS newbie, expert in electroacoustics