The 32-bit VoIP board can, as of tonight, play media from a microSD card inserted into the onboard socket.  This has the added bonus of demonstrating that the code segments for fragmented file handling, file name caching, SD card file searches, and cooperative multitasking all work as they should.

Right now, the handler for audio playback is the SD card filesystem reading layer.  It’s specific to audio tasks, but a bit of rewriting should make it much more general so that every task needing SD card access will be able to use it.

This means it’s time to start working on the Ethernet capabilities of the server.  This comes at a time when the semester is starting to pick up, so we’ll see how quickly this is accomplished.

I’ve spent a few hours (okay, okay, more like 20 hours) over the last two weeks working on implementing SD card support in MIPS assembler.  As of approximately 15 minutes ago, the code successfully implements some subset of the SD SPI protocol as well as FAT32.

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Perhaps you’ve read the original VoIP Server project article.  If you did, you probably noticed that while it works, it’s woefully lacking in processing power.  Ben noticed this, too, and set out to work on an upgrade.

The upgraded server has a 32-bit microcontroller, 10/100 Ethernet, a dedicated DSP for decoding compressed media, USB, and a switching power supply on-board.

The board does not exist yet, but here’s an Eagle3D rendering:

This project was featured on the Make Blog in October 2009.

I’ve always wanted to embed an Ethernet port onto something. This, I claim, is an Electrical Engineer’s trait. I also just like networks.

This project is, without a doubt, the most ambitious I have attempted to date. The finished product (or almost-finished product, as the case may be) has several significant subsections. Aside from the hopefully-obvious TCP/IP component and core processing circuit, there’s a file retrieval subsystem, an audio subsystem, and a user interface of sorts. We’ll explore these in (roughly) order of increasing complexity.

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