uscjeremy · HackerTrans

vor 3 Jahrendiscuss

Thank you so much for these very kind words. One of my personal pet peeves is people who see a passion project that has no practical purpose and say "You obviously have way too much time on your hands." Your comment was the opposite so I particularly appreciate it!

uscjeremy

vor 3 Jahrendiscuss

Thank you!

uscjeremy

vor 3 Jahrendiscuss

If you're ever in Seattle, the rocket is open for tours!

uscjeremy

vor 3 Jahrendiscuss

Hah, that would definitely be thematic!

The aesthetic we were going for was more Apollo Guidance Computer, so 7-segment LEDs were perfect. It turned out to also be a great design choice software-wise because the entire rocket originally ran on an atmega328 which had only 2k of RAM; there really wasn't much room for frame buffers. But the state of a 7 segment digit (plus one decimal point) fits perfectly into one byte, so the entire rocket, which was originally 14 8-digit rows, needed only 112 bytes of frame buffer.

By about 2012 we wanted to write more complex software, so I made new revision of the main controller that took an atmega1284, which has a lot more RAM (16K, vs 2K) and program space (128K, vs 32K).

The big retrofit in 2019 went to a 32-bit STM32 which had a hardware floating point unit, making it possible to do fancier animations. The rocket now supports the classic "snake" game.

But still just 7-seg LEDs :)

uscjeremy

vor 3 Jahrendiscuss

We're really hoping we can find it a home in a park somewhere! Jon's youngest is getting to the age where the rocket is becoming old hat so we're trying to find a place where people can enjoy it, rather than letting it sit unused (or scrapping it, the horror!)

uscjeremy

vor 3 Jahrendiscuss

I don't have numbers so I'll just say that it has only ever been disassembled slowly and according to plan!

uscjeremy

vor 3 Jahrendiscuss

Thanks, I'll get in touch!

uscjeremy

vor 3 Jahrendiscuss

Honestly, this thing inspired my imagination more than I could have imagined. I had so much fun that I ended up building dozens more embedded systems projects, and eventually redirected my career more towards embedded systems, too. Embedded systems really let you interact with them in a tactile way, as you put it, that computer-based software does not. I found it irresistible.

Jon's oldest child -- pictured on the web site as an 8-year-old -- is now a sophomore in college, majoring in engineering. I'd like to think the rocket had some small part in that, too.

uscjeremy

vor 3 Jahrendiscuss

Thanks, that's a kind offer! I think we don't have another move in us for a temporary display, but once Jon's kids are grown it'd be great to find someplace to donate it to permanently.

We actually did haul the rocket hundreds of miles to Maker Faire years ago:

https://photos.app.goo.gl/ESRsJChacRbvpqZU7

Here it is taking on hydrazine:

https://photos.app.goo.gl/1tcRasHpkVJUHq9s7

We had a line of kids waiting for "rides":

https://photos.app.goo.gl/gV9p6a8cVjWqeWgg9

uscjeremy

vor 3 Jahrendiscuss

Thanks! Yes, many new photos though we've been derelict in updating the web site ever since the big 2019 makeover!

Here are some of our end users enjoying our efforts:

https://photos.app.goo.gl/8zca5kXXbAf2vcJh6

Here's disco mode, though I think this is with the old audio synthesizer:

https://photos.app.goo.gl/vkenYZKATyDRB1386

The original rocket's primary display was 4 rows of 7-segment LEDs. It was actually just 4 of our 1-row boards all stacked on top of each other. For the makeover we replaced it with a native board that had 6 rows:

https://photos.app.goo.gl/Dtiv5dN8FfrBAkDK7

Here's a video of it playing pong on my bench before installation:

https://photos.app.goo.gl/bWfQkTaF3eUyacb78

The old display boards were controlled by bit-banging latches over long parallel cables. This turns out to be a very bad idea (any EE could tell you this, but we're computer scientists). In the 2019 update we changed the remote display control from bit-banging to proper networking using I2C-based packets. We didn't want to remake every single display board, so we came up with a shortcut: we designed little snap-on "dongles" that speak the new I2C protocol and translate to bitbang commands that just go a few cm to the display board below. Here's the dongle installed on one display board:

https://photos.app.goo.gl/z9e6z6p4vXgb5j5aA

Here's a side view showing how they stack:

https://photos.app.goo.gl/tAzF4Aeq1dWVHFxE6

And here is one of the new dongles in situ with the new STM32-based primary controller, and the upgraded 32-bit audio synthesizer:

https://photos.app.goo.gl/oQxEZKRUZsK4Ry6W7

We're both pilots so of course we had to put in a Hobbs meter. The rocket has over 600 hours on it:

https://photos.app.goo.gl/ydecF3q8VkdnJB1JA

uscjeremy

vor 3 Jahrendiscuss

Fun story: jonh's package for doing embroidery for inkscape was forked years later to become the excellent and much more comprehensive InkStitch extension (https://inkstitch.org/)!

uscjeremy

vor 3 Jahrendiscuss

You're right, it's technically more of a fort than a treehouse. The original concept was a treehouse and we kept calling it that even as the plans changed. It's near trees, though :)

uscjeremy

vor 3 Jahrendiscuss

Thanks dang! I'm one of the makers and happy to chat!

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