Nerdy Texts of Analog and Embedded Systems Wizardry

It’s built!
All the footprints work, nothing smacks anything else. Physically no failures. And it’s pretty!

Here’s a closeup of the memory expansion:

Onwards to power-up!
xo
TB

A very exciting day! It’s like this:

…and like that:

and like this and uh:

These are the gerbers for the new WTPA2 and its Flash daughterboard, and the REAL THINGS fresh off the jet from Advanced Circuits! The new kind-of-questionable-but-kind-of-awesome through-hole SRAM got here also:

So these all can go together today!!! There’s a ton of new firmware that I’m still working on to support new features, so we may not hear any crusty samples, but I’m hopeful we’ll get to see some lights blinking at least before sundown. It’s da future!
Stay tuned,
xo
TB

So if you don’t know how low I will sink to make a prototype work, now you do :-)
xo
TB

Yesterday the PCBs for the Mess Tool came in and I populated them. Like a big dummy I forgot to order the LT1203, so testing was relegated to the bench until today. This turned out to be a good thing, since of course there were legit problems which needed attention.
You can see from the pics that there’s a proto area in the mess tool. That ended up being a good thing. Part of the circuit is a set of clamps which let you keep whatever gnarly signal you’re injecting into the poor unsuspecting TV from spilling over into the sync region.

These clamps ended up being the source of some trouble — they were mushy passive clamps which put a 47k in series with a video signal, which it turns out is TOO MUCH, since all that pretty ground plane (and the IC inputs, and whatever other parasitic stuff is going on) contributes significant capacitance at color frequencies. The diodes I was using to clamp to a reference (SD103s) turn out to also have a 50pF capacitance or so at 1MHz, which again, counts for a lot.

This means that the video through the “snarled up” section tended to just get filtered away to nothing. The solution was (well, will be, I’m still building it) an active clamp which lowers all the circuit impedances and generally burns up more current.

The mux came in this morning (and Digikey was out of parts in the correct footprint, grumble) as did the boards for the synth and some low-capacitance diodes. So today will be busy. More soon.

Also. Not to get gooey, but man do I love hardware. Really. I forget that in the good old days it was me and a scope and I never ever wanted to learn to program. You know, when men were men and all that.

Xoxo, TB

Heavens!
Back in Chicago, rode hard, put up wet. Bent 2008 (which ruled) and a certain amount of hanging with hipster rocker dudes (get up late, sweaty) resulted in some pretty killer new patches for my lil’ blood.

In the meantime, big propers to the four brave souls who bought up the 0.9 kits! Below, for their benefit, is a really big and slow to load (and unapologetically un-artsy) photo of my kit which shows off where all the components go because my silkscreen layers in the PCB files are still a little crunked up. It’s late, and I just built new linkages for a small robot combine harvester. Really.