In the past few weeks I made some developments on the alternative solutions.
First I made a hardware decoder for timecode signal, which eliminates the analog audio processing in software or firmware. And I also added an external I2S DAC to the system to be able to use and test all 4 channels of audio. Here is a video of the new hardwarare unit. It is still the MIDI controls the iPad application but the midi signal is made directly from the vinyl audio.
Here are some pictures of the system now. I made modifications of the code to handle the second DAC, but it is not perfect yet.
This is the hardware decoder for timecode signal. It is more or less a RIAA corrector and comparator for sine wave. The tricky part is that it works with a single 5V supply of USB port and it is more or less independent of the signal amplitude coming from the cartridge during fast and slow vinyl moves.
The other improvement I made is my 3D printed stand for the optical mous PCB which is here:
iPad turntable controller 
How is it all going along? 🙂
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I paused the project for sometime. I am too busy to develop 🙂 Maybe some day I’ll continue.
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Do you have any plan to finish it? Any chance to release sources or so?
Thanks!
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It is not likely I will ever continue this project. But I think I can release the source as is.
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I will love to help in some way. How can we contact directly? Mail or similar…
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Hi! We can contact by mail. gorcs.gergely at gmail dot com. But I will not continue this project because I sold my turntables 🙂
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Yes, please release it! Would love to take a look. Thank you 🙂
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Is the code available somewhere? I am super interested in building a 4 channel USB audio/midi interface using the STM32F4 processor. Thanks!
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Unfortunatelly the code is very dirty and full of other unrelated stuff, so I haven’t released it yet. I am happy to help you out if you have questions. I described how to make the 4 channel card in the previous posts with details.
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Interesting work. I will invite you to join this board and share your thoughts and resources (as some of us done even in ttm/cdx) and diy.
http://www.digitalvertigo.co.uk/forum/index.php?showtopic=38093&page=14
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Thanks for the invitation. Unfortunatelly I cannot post to the forum however I was registered.
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Yup I must to send a mail directly to administrators… I posted your blog so I expect some answer from the people involved. Meanwhile if you want to talk with my directly add an (ab) and gmail to my name 😉
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Now I managed to post 😉
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