The workaround: Simply desoldering the output pin of the LDO (red circle in second image) brings the GPIO pins back to life, at least until the new LDO arrives. Already ordered!
However, the rest of the board leaks voltage to the LDO output trace, with an impedance low enough to power the Jetson module's side of the level shifters with 1.2V.
Not quite the intended 1.8V, but close enough to discriminate between high and low.
The GPIO pins started getting weaker despite no load (outputs at 3.3V in HIGH, but 2.8V in LOW) until they stopped reacting completely eventually.
Turned out the 1.8V low-dropout regulator (LDO) powering the level shifters between the Jetson module and the GPIO header died.
Should pivot to repairing Jetsons if all this AI robot thing flops. Over time, I've reversed engineered parts of the carrier board.
Here's a simple fix for dead GPIO pins ⬇️
Why so? Is it because they’re used for warnings and errors?
You'll have to tap on the left image to see all the icons.
Why are all my apps blue and green now?
Our robot’s voltage regulators passed all our validation tests this week!
It’s hard to get these at once:
-stable output voltage
-wide input voltage range
-high output power
-small footprint
-reasonable temperature increase
The latest prototypes show them all consistently.
3D printed power button and LED diffuser. I must have done like 20 prototypes of this part alone. My son now deems it "satisfying to press" (sound on).
What scares me most about relying too much on AI coding is that I might replace talking about what I do with talking about how productive I became.
Hahah my button has an existential crisis due to its perceived lack of agency in the world. Always being pushed to perform.
The most unexpected lesson from this week is how difficult it is to make a button that feels ok.
Silicon Valley has been exploiting the idealism of high achievers for decades.
I've seen many times this sort of reaction, to the realization that the company ultimately prioritizes making money.
History rhymes.
Narrator: it was not.
This newsletter could have been sent last week, right?
It is from 10 years ago.
Oh, no. Another robotics company that could not secure funding. I really liked their vision of approachable humanoids.
Some device tree black magic, I2S sorcery and I2C spells later and we got audio output!
(audio is a tribute to HF1's favorite cousins)
Happy Groundhog Day!
Just a matter of time that bad agents catfish legit agents into giving away user information. Security is going to be fun.
So, I was able to make the Jetson talk to the audio chip via I2C, configure the PLL and clocks of the I2S interface, power the mic and read back audio (still not reaching the Jetson).
Here's the Jetson saying "hey, chip, gimme register 6" and the chip replying "Mkey, it's 0".
Today, 10 years later, it came back. Out of the blue. No conversation with my coworker. It did not take over my thought process, so it was actually fun, like a warm memory.
I decided to share it with you all, because what’s life if we don’t enjoy a bit of weirdness?
The first few times, it was a funny glitch. I had to make an effort to not laugh. But then it became a bit annoying. Not that I was unable to control it, but it could feel a bit invasive.
I never told my coworker because it was too weird of a story to mention at work.
So, back to my coworker. Every time he would mention Villa Granada in a conversation, my brain would start sounding the Copacabana backing vocals saying “Villa Granaadaaa” multiple times.
Here’s the thing: my brain went Rio->Brazil->Copacabana->1985 movie of same name->Barry Manilow, and his Copacabana song started playing in my head. Mainly the last part where the backing vocals goes “Copabaanaaa”. Only that, instead, it was “Villa Granaadaaa”.
The apartments, the outdoor area, the pool, maybe the choice of words of our guide that day… I don’t know what it was, but something made me think of the movie Blame It On Rio, with Michael Caine.
This is going to sound weird. I used to have a European coworker in the Bay Area who was once looking for a place to rent. He ended up at a condo called Villa Granada. I had also been looking, so I had visited the place.
Today it's audio day.
My latest robot PCB has an audio codec. Let's see if I can make the Jetson interface with it over I2S+I2C.
It involves tinkering with device trees, so I don't expect it to be easy, but I'm so excited for hearing HF1 for the first time!
The new motor drivers and servo feedback in the latest PCB worked like a charm!
After a long battle with regulator overheating and ringing, it's nice to have a small victory.
The redesigned regulator coming in the next batch of PCB prototypes will hopefully behave, too.
