The idea for creating a USB sound card based on a PIC came from discussions of other people creating one on the Microchip USB forum. The hardware of the card is based on all Microchip products. The software uses a modified version of the Microchip USB framework which is interrupt driven instead of the traditional polling. The device is a USB composite device. The first device is an implementation of the USB Audio 1.0 interface and the other device is a custom interface based on a HID interface. The purpose of the custom interface is for programming the device serial number, upgrading the firmware, and in the future any other configuration that isn’t supported directly by USB Audio 1.0. In a previous version, WinHTTP was oringally used. After testing the card for awhile, I decided its better to not require drivers for the card especially since the HIDWinUSB interface is rarely used.

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