DIY stupidly cheap tire temp logger

I started this project since I think I can get a lot of valuable info about both my car setup and also my driving by seeing how the tire temps vary, at 16 points over the tire width, along different track sections.

Racelogic has a system and these guys have a similar system:

https://m.youtube.com/watch?v=S0TlRkNWheQ&t=0m47s

https://www.youtube.com/watch?v=JZIV_yDptDo

But there is one problem for me, cost. I'm just a trackday and hobby racing nerd. Racelogic's system will set you back 20K-40K $. I'd rather spend that money on track time entry fees and tires.

So what could I do... Well, I always use a bluetooth 10Hz GPS and my mobile phone for logging and video recording. So I made an open source DIY bluetooth sensor kit. Each sensor connects wireless to the phone with low energy bluetooth and has a 16 point IR-array temperature sensor plus a distance sensor for logging your suspension's movement. 

If you already use your mobile phone and an external GPS for logging you only need the sensors to get going. A complete sensor is around 170$ per wheel in parts. And on many cars you'll get far only logging two wheels if you want to keep costs to a minimum.

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Current status Dec 31 -18 

- the temp sensor with bluetooth is all done and dusted, running fine

- the distance sensor code needs some error handling added

- Design/CAD of an open source 3D-printable enclosure - I'd LOVE some help here!

- the two major track loggers for mobile phones www.gps-laptimer.de and www.racechrono.com already have units and have both done initial tests for integrating support for the sensor

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More info, status updates and all source code https://github.com/MagnusThome/RejsaRubberTrac

Discussion thread (in Swedish but feel absolutely free to write in english!) https://rejsa.nu/forum/viewtopic.php?t=113976

Wow, this is super-cool! Thanks for sharing.

Github page updated with some more info https://github.com/MagnusThome/RejsaRubberTrac

Very cool!

It's ALIIIIIVE!

MUHAHAHAA!

https://www.youtube.com/watch?v=Yuy62oPXugs

These wires are all you have to connect but....

I designed this small board so there are no wires (soldered wires is not the best idea in a shaking car). Getting a pcb made these days is amazingly cheap, I was surprised (many years since last time I did this). I ordered just a few and they were $0.95 a piece plus shipping. Got them within a week.

I also made a sub forum for anyone wanting to help out with the project or wanting to dive in and build your own:

www.rejsa.nu/rejsarubbertrac

Will this log data, or is it just a live display through Harry's?

YAAAAAAYYYYYY!

Since the DIY microprocessor/hardware interfacing products became a thing, I have been trying to find the time to get my coding freak on and make one of these systems.

Thank you, thank you, thank you.

collinskl1 said:

Will this log data, or is it just a live display through Harry's?

Both Racechrono and Harry's are working on log and export. Exact dates when they will release what functionality, only they know. But both are spending serious time in developing support for this kit :-) 

The very very best is to mail and ask both, showing them interest will absolutely not hurt their planning ;-)

EDIT: Or ask in their forums, probably the best way.

Ermagawd.  I need this!

Whip out your soldering irons or start canvasing your friend lists for who to ask for help, hehe!

You need to be able to:

- do some very basic soldering

- upload the code to the board over USB. There are a handful of steps to do it but I made a very clear step by step guide here on github: 

https://github.com/MagnusThome/RejsaRubberTrac/blob/master/installArduino.md

- Make/get and enclosure. I'll supply files on github that you can download to 3D-print a case (there are online services where you can order print). The files are not done yet though. If you plan to make your own enclosure pleeeeze share your ideas and result on https://www.rejsa.nu/rejsarubbertrac !! :-D

Cool stuff, wonder how I could incorporate these with Race Capture Pro...

ross2004 said:

Cool stuff, wonder how I could incorporate these with Race Capture Pro...

A quick look says it supports bluetooth (BLE?), is that for sensors or something else?

EDIT: Seems it's only Bluetooth 2.0, no BLE. Too bad. The analog and digital inputs won't get you far since four wheels generates 64 data channels of temperatures hehe.

EDIT2: Maybe rewrite the code to send data to CAN bus instead of bluetooth... There are CAN bus interface modules and libraries available. Haven't checked these out though.

EDIT3: Can you log data coming over Wifi? Then that's probably the easiest rewrite IMHO. The sensor kit will draw more current though (it now takes around 10-15mA only), use a bigger chargeable battery or just use car's 12V directly.

MagnusThome said:

ross2004 said:

Cool stuff, wonder how I could incorporate these with Race Capture Pro...

A quick look says it supports bluetooth (BLE?), is that for sensors or something else?

 

EDIT: Seems it's only Bluetooth 2.0, no BLE. Too bad. The analog and digital inputs won't get you far since four wheels generates 64 data channels of temperatures hehe.

EDIT2: Maybe rewrite the code to send data to CAN bus instead of bluetooth... There are CAN bus interface modules and libraries available. Haven't checked these out though.

EDIT3: Can you log data coming over Wifi? Then that's probably the easiest rewrite IMHO. The sensor kit will draw more current though (it now takes around 10-15mA only), use a bigger chargeable battery or just use car's 12V directly.

1) Thank you!!

2) this is very cool and interesting, also currently "above my technical pay-grade" LOL! if there is a Kit form of this set up with all the design work completed in the near future, i'd be all over it, please keep us updated!

matt

Matt said:

1) Thank you!!

2) this is very cool and interesting, also currently "above my technical pay-grade" LOL! if there is a Kit form of this set up with all the design work completed in the near future, i'd be all over it, please keep us updated!

matt

A kit supported by Racehrono and Harry's Laptimer (and maybe more...) - Yupp, it'll be a doable step by step guide. What parts to purchase and exactly how to put it together.

A kit supported by Race Capture Pro - Dunno... I'll look a bit at it. Either support is added in their end. Or in this end :-)

I updated the github page with info on places where to buy the three boards (and prices)

https://github.com/MagnusThome/RejsaRubberTrac/blob/master/README.md#easy-to-build

Around $90 per wheel for everything (the three boards and the chargeable battery). And then find a friend who can 3D print the enclosure :-D 

I guess having just two kits is a good enough start for some?

Waiting for public beta or release of Harry's and Racechrono though. I just have the early non-public beta of Harry's. Also to do some proper field testing. Too cold at the moment...

Thanks Magnus.  In the North America market, we have an easier time getting the IR sensor as a component, and it's easy enough to deal with that.  But as far as I can tell the distance center is surface mount only.  It's easily available here as a board too, but just curious -- will the code run without it?

JBasham said:

Thanks Magnus.  In the North America market, we have an easier time getting the IR sensor as a component, and it's easy enough to deal with that.  But as far as I can tell the distance center is surface mount only.  It's easily available here as a board too, but just curious -- will the code run without it?

Yes, both Mouser and Digikey stock the sensors as components. And yes, the distance sensor when not on it's daughter board is the only component that is surface mount only.

If the distance sensor isn't mounted you'll actually get slightly faster temperature updates too. You can actually plug the sensor in and out and just push reset or cycle power and the board configures itself accordingly. 

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You don't need the board I've done, connect the sensor daughter board/boards with just five wires and you're done. But... I'm already finalizing an updated board with some added features. Swiss army knife style options to pick and choose whatever you feel you need: 

- 12 volt power input. This means you can run the board directly from the car's power or other sources up to 30V. Both through hole and smd components fit. 

- Simple power on/off switch. Not the final solution for tough environments but you can connect cables to a tougher one here instead if you want. If no power switch is present the board defaults to be powered on thanks to the switch activating a power disable pin on the power circuit when it's present and activated. 

- Sandwich mount temp sensor daughter board OR just direct mount temp sensor as a component. 

- Sandwich mount distance sensor daughter board OR direct mount distance sensor as a component (surface mount)

- Li-Ion battery holders. So you have the choice of connecting either a flat chargeable Li-Po battery to the JST connector or use a battery holder for either a Li-Ion AAA (10440) or AA (14500) size chargeable battery. Li-po connectors are either JST-PH 2.0 or 2,54 or 1,27 mm.

- Three solder jumpers (knife cut trace) for optionally hardwiring each sensor unit to be named (Bluetooth device name) Front/Rear and Left/Right. This can alternatively be set in the software code before uploading to each sensor. 

- One solder jumper (knife cut trace) for optionally mirroring outside/inside of the tire for the temperature sensor. This can alternatively be set in the software code before uploading to each sensor. 

- You can mount a dip switch in place for the solder jumpers but it makes the whole kit a bit larger. 

- All components but the distance sensor can be either through hole or surface mount.

This kind of standard switch has a lot of optional plastic button tops in many colors and shapes.

But has anyone seen some rubber button or other solution to make it seal at least a little better to slow down dust and moisture getting into the box? This button just as it is now is for sunny day races only hahaha.

There are really nice tough sealed buttons out there but they tend to be expensive. And not that small...

Yaaay, found a small small space in a corner where I could fit a pin header for coding wheel position with small removable jumpers. It just just clears the IR daughter board. So no trace cutting or solder jumps needed. 

A, B, C for wheel position

"Mirr" for mirroring tire outside/inside of temps

Solved the sealing for the power button to prevent dust and moisture to enter the enclosure

So that's sorted :-D

First version ready to 3D print! PCBs v2 arriving tomorrow friday :-)

Im dumb.  I want this but that was a lot of spark geek talk for an m.e.  just sell me a plug and play version for less than 1k.

wvumtnbkr said:

Im dumb.  I want this but that was a lot of spark geek talk for an m.e.  just sell me a plug and play version for less than 1k.

QFT. I'm confident in my assembly skills, but the code has me sweating.