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README.md

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 # usb-spdif
 USB audio S/PDIF output
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+This project uses the microcontroller PIC32MX270 to read audio data from an USB host and to output a corresponding SPDIF audio stream over an SPI port. The SPDIF bitstream is generated in software. As a consequence, no special encoder chip is needed. An optical SPDIF transmitter can directly connected to the SPI/I2S port of the microcontroller.
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+The binary image for the microcontroller can be compiled with the [`ChipKIT toolchain`]. Simply change to the `src` directory and type `make`. It should also be possible to use the XC32 toolcain (requires chaging the first few lines of the Makefile); but this has not been tested.
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+[`ChipKIT toolchain`]: https://github.com/chipKIT32/chipKIT-compiler-builds/releases