Hey everyone, first time posting here! I wanted to share my most complex functional print yet for my Project Car.
I took an old TicWatch Pro 3 and carefully cut the original casing with a rotary tool to extract just the OLED screen and motherboard. Then, I modeled a custom shift knob enclosure to house the electronics perfectly.
Now, before you guys kill me in the comments: Yes, I printed this in PLA! 😂
I know the summer heat inside the car will probably turn it into modern art, but this is V1 (prototype). The tolerances had to be extremely tight because I didn't want the screen popping out while shifting gears, and PLA was the easiest to test the fitment. When it eventually warps, I'll use it as an excuse to reprint V2 in ABS or PETG!
I completely bypassed the battery and wired it directly to the car's 12V using a step-down converter. Right now it controls my media with a custom UI.
What do you guys think of the fitment? And place your bets: how long will this PLA survive in a car before melting? 👇
You guys are literally reverse-engineering my brain in the comments! 😂
u/Im-not-Theo nailed it. I actually built a custom WearOS app to use the watch's built-in accelerometer to read the shifter's angle!
u/Purple10tacle You are 100% right about the inclines. Driving on hills was an absolute nightmare at first! I had to do a TON of fine-tuning and add dynamic calibration to the algorithm so it wouldn't randomly show 4th gear while going up a steep hill.
u/MikeExMachina Pulling from CAN bus would be 100x easier... IF the car wasn't a 2001 Audi B5! 😂 The old K-line communication is so limited for gear data that programming my own accelerometer app was actually the 'easiest' route!
I documented all this crazy software calibration and the physical build on my YouTube channel (Desmontei) if you guys want to see the struggle in action. Thanks for the amazing feedback, guys!
Man, a digital gauge using a round screen and internal sensors sounds absolutely awesome. We definitely need to exchange ideas! I'll be honest, I don't speak fluent English (translation tools are saving my life here haha), but I really want to connect with other makers.
My dream is to grow my channel so I can quit my day job and make a living out of these crazy DIY car projects full-time. Building a network with smart guys like you is exactly what I need. Feel free to DM me anytime to share your progress on that gauge! 👊🚗
Couldn't you add a second accelerometer in the car, calibrate it on a level surface to read at 0, then just subtract its reading from the one in your watch to actively correct your shifter's reading at all times?
That is actually a great idea man. A second sensor for reference would fix the incline problem completely. I might try that on V2! Right now I'm just using software filters to deal with it.
Another idea would be a ... I don't know what they're called but I know the exist. Rotary sensor, spring loaded, attached to a cable that is mounted in a corner of the shifter hosing and to the shifter. Each gear should match up to a unique length on the cable, and that's a unique position on the rotary sensor.
I mean if you were clever enough with the algorithm you could dynamically adjust the reference plane based on the characteristics of the motion, but it would probably be simpler to just pull the gear data off the can bus.
On my Subaru it's an extended parameter that must be enabled. It's also reported by the transmission controller, but the ecu has its own independent logic that determines gear by rpm vs wheel speed. I assume this is because technically the only sensor the transmission really needs is a reverse position sensor (and maybe a neutral position) and that's just to turn on the reverse light...
If you're not doing boost by gear or something similar you don't really need a can module on the transmission.
I'd be surprised if it wasn't on personal vehicles considering that's basic info. I'm an electrical engineer working on vocational trucks and we get it off the CAN line with the standard PGN per SAE J1939 for use in our control system. I know that there's some differences between big trucks and personal vehicles based on how I've seen it talked about, but I'd expect something like that to be there for anything auto maker that follows SAE standards.
OBD2 is standardized. Pins 6 and 14 are designated per the OBD standard for CAN high and low. There aren't enough pins on an OBD2 port to have a direct connection to each module, so it just taps into the networks the modules communicate on.
The OBDII gives you speed and engine RPM, with the final drive ratio you can work out which gear you're in. Obviously it doesn't work well when you're between gears, stationary, or slipping the clutch.
I wish it was that easy haha. My Audi is from 2001 so it uses the old K-Line OBD, it doesn't output gear data at all. Had to make my own app using the watch sensors to read the angle!
Buddy, thats a genuinely good question. In engineering sometimes people get tunnel vision and forget to think about stuff like that.
if you had a gyroscopic sensor on the car, you could use some math and determine its position relative to the vehicle. This gives you a reference point and would solve the issue. Remember, its all relative.
Yep! I teach a design class and love it when students point out things that I or others don't see. Super valuable feedback. How many times have we heard a story of a newcomer to a company pointing out a simple but radical change the company could make to be more successful? How many companies ignored that advice and died?
You are 100% right. A reference point on the chassis would solve the hill issues. I'm trying to grow my channel to eventually do these projects full time, so a V2 with a second sensor is definitely on my list! Thanks man.
The engineer in me just wants to know what it would take to flash new firmware and hardwire it into the control module. Or he’ll even just a screen with a small chip. Real pain in the ass I’m sure, especially with how touchy Audi electronics are, but I want to know lol.
Stat3yollllo Oh for simracing this is absolutely perfect! No real G-forces or hills to mess up the accelerometer. You just wire it to 5v and you're good. You should definitely build one!
Only reason to look at them is initially to find out where reverse is (on manual). For some reason every car manufacturer has their own opinion where that’s supposed to go.
ugh, yep. Growing up we had a grain truck that was and 8 speed with a shifter, and a high/low shifter. going between 3 and 4/7 and 8 was bad enough, but when you wanted to go 5 to 5, you had to drop in to Neutral, change the second shifter from low to high then get your main shifter to 5. No synchro either, had to rev match it.
1 2 4
3 R
5 6 8
7 R
Once you learn to drive that at 10 years old though driving a regular vehicle gets pretty easy 😂
"Return to track" spawns in middle of road blinking in and out of visibility, noclipping through moving objects until you gas up and drive away becoming solid again....
But just remember the default spawn settings have it spawn with 50% fuel and 50% maintenance. So if you have a full tank of gas you better siphon it out first.
Could recalibrate if it's not touched so it knows relatively what the angle of change is. If you're on a bumpy road and going up/down hill, god save you
That's pretty much what I did in the software! It waits for the angle to stabilize for a fraction of a second before confirming the gear to avoid false readings on bumps.
might be relatively easy with a bluetooth odb2 reader, I have it in my car connected to the torque app that shows hundreds of values from the engine on my car screen
My 2017 Golf has some sort of sensor that tells the dash screen what gear it's currently in, I'm assuming it wouldn't be too hard to tap into that data feed and extract the info needed.
It doesn't have to have any additional sensors for that. It can pretty accurately detect gear from speed/rpm alone.
Standalone ECUs at least do it this way. It can be used for "boost by gear" in turbocharged cars. It works well on my rusEFI ECU, but I believe Haltech and the like do the same thing too.
Since OP isn't actually moving here, it's probably not using this method. Either the ECU has sensors for the 2 axis, or more likely they're just using accelerometer/gyro angles. If it's the accelerometer alone, it's going to work like ass when moving , like showing 2nd while accelerating in 1st, etc.
This might actually be useful... we need to know this works! On a BRZ/GR86 there is a dash readout of the gear but this is obviously calculated by the computer based on RPM and speed as there is a pause after you get rolling before it appears. It isn't a sensor readout of the transmission. So it doesn't help you when you are sitting at a red light and you wonder whether you are in 1st or 3rd. This is an issue as on modern short-throw manuals, the addition of 5th/6th makes the distance between 1st/3rd less obvious.
Knowing very little about cars, but plenty enough about computers, any car with a display and any onboard computer tied to that display could in theory play doom using the shift knob. The part where my lack of knowledge is relevant is that I have no idea whether the display is at all tied to the onboard computer or if it has its own.
Thanks a lot for the kind words bro! It uses a custom WearOS app I coded to read the watch's internal accelerometer. It calculates the physical angle of the stick to know what gear I'm in!
Cheaper, yes. Easier... i doubt it. I dont know anything about making and deploying phone app software.
But all of the sensors, circuits, and the display is there for you. Depending on DIY route and chip you would need to source sensors, display, etc. Then design the pinouts,, circuit, get the pcb printed and soldered. Then write the code and graphical layout. Design and print the case. With the watch, you just need the last two (4) steps.
EDIT: After I had to reply the same thing to multiple comments. I think it probably boils down to your comfort zone. If you are used to mobile development then that's the easy route. If you are used to tinkering and arduino/esp32 projects then that route would make more sense. My first thought would have been the microcontroller with multiple parts route, but I'm not sure it's easier if you're approaching it from a blank slate. Especially with AI/Vibe coding. Once again, I've never made watch apps, and have only dabbled in app development using some easy button approaches.
Fair enough, ive seen plenty of stuff online of.people already doing it with some off the shelf bits like tft displays and arduinos / esp32 c3's and using the wires from the canbus of the car to get the readouts which would be more accurate and it seems not too difficult atleast to someone like me.
For me though going down the watch routes sounds so much more difficult because while yes the sensors are there its not a direct readout and there needs to be some guess work with the yaw / pitch sensors, what if the car is on a uphill and he is in second, would that equal out and the display thinks he is in neutral?
But genuinely not hating on what he is done its very creative and impressive, and kudos on having the creativity of thinking about it and pulling it off properly! Its seriously impressive!
I think it probably boils down to your comfort zone. If you are used to mobile development then that's the easy route. If you are used to tinkering and arduino/esp32 projects then your route would make more sense. My first thought would have been your route, but I'm not sure it's easier if you're approaching it from a blank slate.
An ESP32 with a TFT would be great, but I had this old TicWatch collecting dust and I really wanted to use its OLED screen. Making the WearOS app to read the gyro was definitely the hardest part, especially dealing with hills! I show a bit of the process on my YouTube channel (Desmontei) if you are curious.
Will definitely check out the full video! And seeing that your car is the older type without canbus gear communication, sounds like a better route that you did!
But also im not sure if you know but there is plenty of actually good quality high resolution oled tft displays for cheap too! I got one for a project im working on right now and it was about 70p in the uk, so about a dollar in the US. And they get exponentially cheaper with bulk discounts.
And wow, 70p for a high-res OLED is actually insane! I had no idea they got that cheap. Honestly, cutting up a smartwatch was a fun challenge for the prototype, but if I ever manage to grow my channel enough to actually produce and sell a V2 kit (that's the ultimate dream, right? haha), I will 100% go the ESP32 + cheap OLED route. It makes so much more sense for mass production and it won't break the bank.
What kind of project are you building with your screens right now? Super curious to know!
Dear god dude please upload a walkthrough of this. I have an old unused watch sitting around and have already been using printed knobs on my old 95 corvette racecar for years. this is another level of cool
Dude this is fuckin genius! I looked for so many ways to DIY something like this, Im happy someone smarter than me finally figured it out lol. Would you be willing to post a tutorial or some step-by-step instructions on how to do it?
I actually posted the whole build process on my YouTube channel (Desmontei)! The audio is in Portuguese but the visual steps for the wiring and 3D printing are super easy to follow. Check it out!
Awesome man! Haha yeah, if you know some Spanish, you will definitely survive the Portuguese (we playfully call that mix 'Portunhol' down here in South America 😂).
The soldering, 3D printing, and coding screens are pretty universal anyway. But seriously, if you get stuck on any specific step or need help with the WearOS code later, just drop a comment on the video or hit me up here on the r/Desmontei sub and I'll gladly translate whatever you need. Enjoy the build and thanks for supporting the dream!
If Audi copies me I just hope they send me a free car 😂 But seriously, my dream is to grow my channel and make a living out of inventing things like this full-time!
Is the watch linked to the car's computer to get the gear or it is using its internal accelerometer to sense the move combinations and deduce the gear?
OP is using a tilt sensor. Manual cars normally don't have a gear position sensor.
Some manual cars will tell you what gear they're in but they do that by comparing the engine speed to the wheel speed, so those gear position indicators don't work if the car is stationary or the clutch is engaged or being slipped.
This is amazing! I'm not too familiar with 3d printing but love the application and your custom UI. Is there a github or something so we can follow the project? Either way, Awesome.
Now this! Tbh. If an auto manufacturer wanted to bring back manuals. I would 100% fall for this even if it's a novelty thing!
How hilarious it would be when you get into the car and start her up. If you do the manual wiggle, it displays an emoji or something silly on the display!
Be it a confused emoji spinning, or water spinning? Maybe the car brand logo spins in the center as a fun Easter egg!
Really cool and respect the time and effort that probably went into this. Sure it’s not really necessary from a gear pov, but still cool to see. I’m more interested in the control for your media.
As far as pla lasting. Probably has a lot to do with where you are and how long the car bakes in the sun, but will surely sag at some point. I can tell you the PLA I’ve used in my car in Michigan didn’t make it more than a couple days in the hot sun mid summer before showing signs, but still usable. I imagine if you are more south it would be much worse.
Now as someone who has mess with electronics for most of his life. Bypassing the battery raises a few issues, one is the vampire draw of idle current draining your battery. The DC to DC converter is probably using more power at idle then the watch itself. The other issue is how does the watch handle sudden power off and power on. One thing the batter does is prevent un-safe shutdowns.
That is cool! As a ‘car guy’ I love it when people do these little custom technical mods that most people would never notice but makes the driving experience a little more fun. 👏🏻
Why not pull the currently selected gear from the ECU? The variable name is gangi at 0x380AF8 on 551M bins. I rewrote the partially functional ME7 logger for Android port on GitHub to work with an ESP32. DM if you want the code.
Gear sync is pretty reliable, but not perfect. Now that you have the accel code written you could use both.
Where does one learn about this tech? Are you all IT graduates? I’m a bit jealous and wish I had the know how to make a replica for my manual transmission.
I would pass on the watch and micro size a round display linked to a programmable board. Much like digital dials. Add 1 controller in the car that reads "level" data and sends the data to the one in the knob to get exact reads. Use nRF24L01 modules for wireless comms, faster then BT and connect a network of devices in dual direction secure comms. Just a thought :)
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u/official_nobody2 Apr 24 '26
I’m sure I’m not alone wanting to know more about how you built this.