Board rev .02

Board rev .02 is nearly out the door. I have finished doing layout and just have to get a few bugs out that freedfm found. This new rev fixes a couple errors in the original revision and also updates the audio codec to the AC97 compatible AD1981BL.

Codec Change

Well, it turns out that cheap isn’t always good. We chose to change the audio codec on the board because it required that we generate three external clocks to feed into it. This used an unjustifiable amount of board resources and also would have required us to change the crystal for the main processor which would have made it harder to implement ethernet in the future. For this reason, the UDA1345TS is out and we have settled on an AC97 codec from analog devices. The new part number is AD1981BL. This codec also has mic and headphone preamps built into it.

Kernel Booting … Done

The kernel boots! We now have the kernel booting out of flash. It then mounts the JFFS2 from the Dataflash chip and proceeds to boot. Not too much can be done with the current image but all of the files are there and we were able to play a quick game of dungeon on the serial terminal. The next big task is to get the audio driver done. There are files in the kernel for the uda1341 chipset which is similar to our uda1345 chipset. Unfortunately this file seems to be a remnant of a driver from the 2.4 kernel and not of the necessary files exist to get it working. Due to this we are starting from one of the ADI chips that has a driver to use the SPORT on the blackfin in I2S mode and then rewriting the parts of the functions that are chip specific. We hope to have a first shot at the driver early next week.