Hack Notes CVA 090426

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Long Overdue Hack Notes from Eric

Eric's CVA Working Again

I spent all week trying to get my CVA working - I had to fix numerous issues, like the death of my programmer pins, the death of my compass chip, various bad solder joints, and of course the complete rebuilding of my armature and display.

But it done - I once again have a fully functioning CVA, which even points north!

Dual Ribbon Display

I tested our idea of using two ribbons for the display, one which carries only power. This worked great - I didn't have to create little extension wires for the motors, and it was therefore much quicker to create. On the downside, I now have two crimps next to each other in the armature and that makes it stand out a little more than I like. In the future I think I would use Skory's design which has the electronics at the end so that crimps are not necessary.

Science of Vibration Management

Skory and I both wore both of our armatures. One armature has an extra layer of foam, the idea being to absorb some of the vibration, thus making it easier to differentiate between the various motors.

Eric: I think the foam makes a real difference, if I ever rebuild my armature I am likely to do the extra work. Motor isolation is far superior with the foam present, but without foam the device is still totally usable.

Skory: (Eric paraphrases what he heard Skory says) Foam helps, but not enough to complicate the armature. For kits, we likely do not need to use foam.

HM55B Female Jack Idea

I rebuild my electronics today to use the HM55B compass chip, because my HMC6352 stopped working. I used our new idea of having a single right angle female header on one side of the board, and a dual row of female headers on the other, and have the compass just jack into them. It worked, I think this is a super great idea for how to get the 90 degree angle that we need without difficulty or a quirky daughter board.

Review of protoboard design decisions with Mikolaj

Mikolaj suggested that we have a footprint for an SD card on our protoboard design. This is an interesting idea, but I suspect that if we use the through-hole footprint for the ATMEGA and shift register and EEPROM, etc we won't have room. But maybe you can use a micro-SD footprint? I think we should delay this investigation until the 2nd rev of the board, just to save time on this job. We need to finish before I go to China, which is on the 1st of May!

I also talked with Mikolaj about the features of the board and he is in agreement that the LiPo battery's have to go. In fact he is switching to other batteries for his belt already, because it's so difficult to charge the LiPos. He likes our compass jack, and our power switch idea.

Anyway, he's on board with getting a couple of boards from us.