@cato@chaos.social
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cato

@cato@chaos.social

Electronics design and hardware hacking, especially passenger information systems • Furry • Be excellent to each other ❤️ • Happy to talk to you! • I'll accept nearly all follow requests unless your profile is empty.
Toots are mostly in English, occasionally in German.

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cato, to random
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Today, my lawn tractor seat arrived and I mounted it to my kart. It's really nicely cushioned and dampened and despite being way too large, you can drive comfortably. You just shouldn't go fast, otherwise you'll fall over.

I'll keep the seats swappable, so I can use this seat for e.g. camping events, to drive slowly across uneven fields, and use the classic seat for going fast :D

The entire Kettcar. Instead of the regular hard plastic seat, it has a big, yellow lawn tractor seat.

cato,
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I'll be adding a lot of fancy gimmicks to my kart very soon. Here's the central control board for all of them which I have just ordered! :D

cato,
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It will control the headlights, turn indicators, horn, motor control boards for rear/front/all wheel drive, a lot of inputs on a control panel and their corresponding LEDs as well as a WS2812 LED strip at the back for displaying lights and turn indicators :3

cato,
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Control panel arrived, most of the controls are populated :3

detail of the panel, now laying on a workbench. most of the controls are mounted, including buttons, switches and leds

cato,
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Aaand that's everything in place!

cato,
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Just noticed how little time I have left to actually work on the kart before GPN. Only a few days effectively, because the rest is time I have already planned with other things. Gotta wire up all the things, mount them to the kart and also write the entire software :D

cato,
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Power wiring renewed, DC/DC converters fitted, now wiring the control panel.

Red ESD mat with the control panel flipped over. Black wires are attached to most of the components, a hand holds the wire bundle

cato,
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Control panel all wired up :3

cato,
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Aaand mounted!

Control panel, mounted, from the back

cato,
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Control panel wiring is ready for the PCB.

cato,
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silicone noises

cato,
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Headlights look so unusual and cursed xD

cato,
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Control board arrived, populated, now on to testing!

Backside of the PCB focusing on a large solder blob across the XT90 and XT60 connectors to properly connect them

cato,
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Mounted to the kart (still untested because I just wanted to know what it looks like) :D

cato,
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Software test :3

Video showing the board mounted to the kart, panning to the control panel. I turn the ignition switch, it beeps and all the lights on the control panel light up for 3 seconds. I then turn the switch back off.

cato,
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the software for this controller is gonna be full of state machines

i normally dislike writing state machines, but once I manage to build myself a nice framework, it suddenly feels much cleaner and easy to extend, if necessary :D

cato,
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Some major progress! All the auxiliary features are working. Now I "just" need to take care of the actual driving :D

Me showing the features I added to the kart. In order: selftest, left and right turn indicators, hazard indicators, headlights, rear lights, reverse lights, hazards with reverse lights, hazards with rear lights, shutdown

cato,
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Some more software work is done - I think I have everything implemented now. Motors seem to behave well - I mostly copied the throttle/brake handling from the hoverboard firmware. Tomorrow, I'll take it for a test ride!
Also - good thing I put both double software serial as well as single hardware serial with a 2:1 multiplexer on my board. Turns out software serial can't reliably handle Rx with 115200 baud, so I switched to hardware serial now, at the cost of my debug output :D

cato,
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One thing that's a bit annoying - for some reason, the compressor for the large horn seems to not build up pressure anymore, so it won't make a sound. I need to figure out what the heck went wrong there

cato,
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Since the compressor is weirdly shaped and doesn't really have any good mounting options, I just used cable ties and a semi-soft foam block to mount it.
I now have a smol honk and a B I G H O N K

View of the front half of the kart from above. Notable is a small, hand-operated bicycle horn on the left side and the big truck horm on the right side.

cato,
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One of the headlights was flickering. I opened it up and while the main light does have a regulator, the ring around it, which can also light up, only has a diode and a resistor in series. I'm running this thing at 24V, the box claims it can do up to 80V. Even at 24V, the pathetic little resistor reached almost 200°C. It measured 130 ohms instead of the nominal 27...

Thermal Image showing a resistor at 187°C

cato,
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I took a 100 ohm, 5 watt resistor and soldered it in instead. I put some silicone around it so it won't break off during a bumpy ride. Much better now and still more than bright enough!

cato,
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Also, I figured out why the compressor wouldn't compress. Well, if you mount it in a way that tightly blocks the air intake...

cato,
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Another silly thing yesterday: One of the wheels showed signs of a motor phase missing, i.e. vibrations, no real torque and generally weird noises. I checked all the MOSFETs and wiring, no problem. I then unplugged the motor, touched the pins together and didn't feel any resistance when turning until I tightly pressed the pins together. Turns out they were oxidised - after cleaning them, the wheel functioned perfectly :D

cato,
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I have had the same mainboards in this kart for years, using analog control. No problems at all, going 50 km/h, across rough terrain, whatever.

I've also had other mainboards in my railkart, using serial control, and three times already I have burned MOSFETs because there was a bump and somehow this caused something to die.

cato,
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Now as part of the great overhaul of my kart, I switched to serial control. I went for a test drive and not even fully off my yard I very slowly went down the sidewalk and the moment the wheel bumped on the ground, same thing as with the railkart. MOSFET burned, Motor control board fried.

I'm just disappointed and sad now

cato,
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So... no kart at GPN :(

Now I need to think about what else to bring and clean up the absolute mess that the past weeks have left in my living room.

cato,
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I collected some info on the failure and possible explanations here, in case anyone feels like reading it https://hd.cato.cat/Po3QZH5hSZWJC0UGmHxBBg

cato, to random
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So I miiiight have spent 300€ on 16-segment LED modules

(hand for scale)

cato,
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Finished the board design! :3

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cato,
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👀

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cato,
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cato,
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THT assembly

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cato,
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THT assembly finished \o/

cato,
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Data wiring... Of course this will all be mounted inside a yet-to-be-built case later

cato,
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It's alive! :D

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cato,
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cato,
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Soo, Gehäusedesign kommt auch voran :)

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cato,
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Case design pretty much done :D I ordered most of the parts!

cato,
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Started preparing the metal parts! :D

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cato,
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The display assembly is done! Gotta wait for the frame parts to arrive :3

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cato,
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Frame parts arrived! Now I can't do anything else until I have the acrylic plates...

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cato,
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ACRYLIC PLATES GET

cato,
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Some wiring and mounting the front plate :3

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cato,
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It does something! This is just random startup data, there's no controller yet.

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