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.

Memory or Forgetfullness

We attempted to test the SDRAM today. We were able to test putting different patterns into memory location 0×00000000 and reading them back. We then tried to do a sweep of all of memory, but we were not able to successfully complete it. The SDRAM chip started getting warm during this process but we are not sure why. Tomorrow we will investigate whether there is any bus contention and we will continue working on our memory test algorithm.

Lights!

Well, we were able to execute code that we wrote on the board. We now have an 8-bit debug interface made out of LEDs. The next issue seems to be loading the bootloader into the SDRAM. The SDRAM is configured but maybe not properly.

Long Time … No Post

Well, it’s been nearly 10 months since I’ve done anything useful with this blog. Fortunately it has not been 10 months since I’ve worked on the project. The first batch of prototype boards came back in December and I have been steadily making progress towards getting Linux up and running on the board. All of the chips (minus the audio codec) have at least had an initial test. This summer I have three other guys working on the project with me their blogs are at Tim Louden Jace Akerlund and Allen T. Waters .

Parts

Well, progress has been going well on the design even though progress on the blg stopped temporarily. I have finished schematic capture. I am now going through my BOM downloading all of the datasheets, verifying part selection and creating needed geometries. However much fun all of that sounds I am looking forward to the layout process for this board. We have found that the Analog Devices reference board uses a 6mil drill for some of their vias. Our normal circuit board manufacturer, Advanced Circuits, can’t do that small of drill hole in their normal boards. We may have to search for someone else to produce the PCB if we can’t figure out a way around this.