colin

@vogon

the evil "Website Boy"

he/him
gameboat.org/

member of @staff, lapsed linguist and drummer, electronics hobbyist

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seattle, WA

colin @vogon10/25/2022, 2:51 AM

colin @vogon

colin @vogon10/23/2022, 6:48 AM

new project: an altimeter/IMU/camera payload for a model rocket

the altimeter/IMU are a custom PCB that I'm still waiting to get back from the fab, the camera is a no-name $12 "spy cam" component available off of adafruit, all powered off of one AAA battery

trying to fit the whole thing inside a cylinder 24mm in diameter and about 150mm long

#diy electronics #model rocketry

colin @vogon10/24/2022, 4:17 AM

sunday night status update: making some progress on the rough geometry of the payload carrier

still gotta punch some holes through it to route wires, design in some space to insert the battery holder contacts, design covers for all the holes and a fairing for the camera lens, and do a shitload of iterative test-fitting, tweaks, and probably a boilerplate test flight or two, but I'm getting there

#diy electronics #model rocketry

colin @vogon10/25/2022, 2:51 AM

got the boards in today

already found the first hardware bug: I labeled the pins of the battery connector backwards

the good news is that apparently these boost converter chips can handle being exposed to -1.5V @ 1.1A for a couple minutes, because once I realized what the problem was the board powered up just fine

#diy electronics #model rocketry

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in reply to @vogon's post:

kaezone @kaezone10/23/2022, 7:09 AM

oh this is so much nicer than anything i've done lol, out of curiosity what micro are you using?

btw i think some ranges get really antsy about standard switches being used for arming? prob not an issue for model scale but yea

colin @vogon10/23/2022, 7:12 AM

oh it's not an actual pyro arm switch, it just arms the altimeter/IMU to start recording when it detects a sudden acceleration

also I'm using an RP2040! it's nice and small and cheap.

kaezone @kaezone10/23/2022, 7:16 AM

ahh ok cool !! figured i'd mention just in case :p

nice, i've been wanting to use that for my next board whenever i get a budget for it! used the Pico for a bit on a contract gig and it was really nice

colin @vogon10/23/2022, 5:07 PM

yeah! the pico's a great proto board and I would just be using the whole pico if I had the space to spare (maybe once I get into mid-power rocketry...)

big selling point for the RP2040 over an STM32 or ESP32 for me is that rpi makes a good hardware integration tutorial that's easy to follow even with zero circuit design experience: https://datasheets.raspberrypi.com/rp2040/hardware-design-with-rp2040.pdf

kaezone @kaezone10/23/2022, 8:15 PM

yeah that doc is super good! i've done basic signal routing and vreg circuits on PCBs but never a proper microcontroller, so it's real helpful

for me i'm interested in it mostly because, besides having good experiences using it for work, it was actually available when STM32s were all sold out lmao

colin @vogon10/23/2022, 10:12 PM

yeah that's what got me to look at the pico in the first place too :p alas, those days are (kinda) over now because people use RP2040s for production, but it's still a great chip!

in reply to @vogon's post:

Aaron Patterson @tenderlove10/25/2022, 3:14 PM

This is awesome. I need to try using one of these RP2040 chips. I didn't realize how cheap they are!

colin @vogon10/25/2022, 3:33 PM

they're great! if you're assembling the board yourself you can get em for $1 each in a pack of 10: https://www.adafruit.com/product/5042

the one thing people complain about with it is that the accuracy of the ADC isn't great (hopefully they'll fix this in a future rev of the chip), but if you only need digital I/O or if you're okay with ~8 bits of accuracy it's hard to beat.

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