Saturday, March 28, 2015

Rev C almost ready!

I've (finally) completed my changes for rev C of Titan. The token is officially passed to Kevin for review. I'll post more about the changes on this rev soon. For now, enjoy:

Figure 1. Candidate Rev C.

Wednesday, March 25, 2015

DDR3 re-check

I decided to double check the DDR3 routing before finishing rev C of Titan, and I found a few length tuning issues to correct. The updates are committed on github:

Figure 1. Superfluous Picture of Titan's Updated DDR3 Routing.

Friday, March 6, 2015

Expansion interface: looking for problems

Before I dive into final tuning I decided to look for any routing issues with the expansion interface. Figures 1-6 show the issues that I found.  I'm going to shift the routing around a bit to try to limit long runs where traces are run closely in parallel.

Figure 1. Tight Routing Between P3 and P5.

Figure 2. Long Parallel Routing.

Figure 3. Too Tight Length Loop.

Figure 4. Too Tight Length Loop.

Figure 5. Long Parallel Routing.

Figure 6. Too Tight Length Loop and Long Parallel Routing.

Thursday, March 5, 2015

Expansion interface: rough tuning complete

I finally found some cycles to work on Titan today. I was able to complete the rough tuning of the expansion interface. I still need to tune the length a bit more, match the differential pairs, and I have a bit gold plating left (by gold plating I mean adding a little bit of beautification polish). The good news is that I had enough room to match the expansion trace lengths; It was not an easy task with the minimum and maximum trace lengths differing by as much as 2.5 inches.

Figure 1. Rough Tuning Complete.