Sunday, June 15, 2014

An Internet music player pt 2

Although I only published pt 1 today, I actually wrote it a couple of weeks ago. In the meantime I have been attempting to move the music player app into the top right hand of the GA144 chip. Nothing I tried would make it work and when I took the app back to the original layout it wouldn't work either! Eventually I found my typing error. The good news is that I learned how to use the async loader so now can update apps in nodes almost instantaneously.

A couple of sub-projects have arisen. One is to down-sample the audio stream generated by the app. At the moment it is generating 18-bit PCM samples but for CD-quality sound I only need 16-bit samples. Down-sampling will also save in processing time.

Another sub-project is to output the PCM stream to a file on my laptop to verify the format. It should be a WAV-format stream but there will be some mystic hand-waving (pun!) to modify the stream into Wav format.

Another sub-project is the work out how to use the SPI Flash RAM to load the app code at startup and then get the Flash RAM out of the way so Wiz550io can use SPI bus.

Another sub-project is to write code to control Wiz550io from GA144 SPI node (node 705). As usual, C-code for Arduino seems incredibly verbose for what it has to do.

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