Tire temperature sensor project

lightningrod · Post by **lightningrod** » Sat Oct 28, 2017 2:57 am

I am considering combining
- 4 MLX90621 - 16x4 pixel thermal imager https://ca.mouser.com/ds/2/734/LX90621_ ... 706890.pdf
- a teensy3.6 (because it has 4 - i2c buses available)

which I'm hoping will allow me to use the new tire temperature page.

I'm very new to the rcp so would appreciate any tips - has anyone done anything like this already.

I've used the MLX with the teensy before although the one I used before only had 1 i2c bus and each MLX uses the same address, so for 4 you need 4 buses.

Is there a how-to interface to the tire temp page guide somewhere?

Thanks,
Rod.

Post by **brentp** » Mon Oct 30, 2017 9:16 pm

Hi Rod,

There's no how to for the tire temperature page, since it's not yet released. However, if you run the 1.12.0 branch and click the tire temperature view, you'll see a popup where you'll see settings. Near the bottom there is an area where you can set the channel name prefix, with some instructions.

The zones are <Prefix><Zone number> e.g. TireTmpFR1, TireTmpLR2, etc.

There is a sample Lua script that we used to make the demo videos; you can play with this today.
https://gist.github.com/brentpicasso/2f ... e425446b63

For your project, I would *highly* recommend broadcasting the data over CAN bus and use the direct CAN mapping capabilities in RaceCapture. Hard to stress this enough. RS232 will work over Lua scripting and the aux input port, but CAN will be easier in the end, operate just like other automotive grade sensors, and you'll have very fast performance using a built-in feature.

Good luck with the project, please do share your progress!

Post by **brentp** » Mon Oct 30, 2017 9:20 pm

Also: https://wiki.autosportlabs.com/CAN_Bus_Integration

lightningrod · Post by **lightningrod** » Mon Oct 30, 2017 10:02 pm

Thanks Brent.

My car does not have a CAN bus ... can I simply connect 2 CAN devices together, or do they need a bus (with power and timing etc) ... to attach to?

Post by **brentp** » Mon Oct 30, 2017 10:08 pm

Ah, it's very easy. RCP already provides the CAN bus, so all you have to do is connect two wires - CAN high and CAN low between your project and RCP.

In fact, you can connect the two RCP channels in loopback (connect CAN1 high to CAN2 high, CAN1 low to CAN2 low) and then you can send messages in lua between CAN1 and CAN2. There are a few lua examples for doing this.

Happy to help as possible. Thanks!

lightningrod · Post by **lightningrod** » Mon Oct 30, 2017 10:10 pm

Sounds too easy! Thanks for the push in this direction. I'll update with progress in a day or two.

Post by **brentp** » Tue Jan 02, 2018 12:48 am

How's the project going? Ping me if you'd like some help

lightningrod · Post by **lightningrod** » Tue Jan 02, 2018 8:43 pm

Thanks for the follow up.
I had some difficulty off the bat getting the can bus communication going. They were out of stock on the Teensy-to-canbus module. While I was waiting I built my own, but was unable to get my Teensy and the RCP to talk to each other. I'm currently suspecting my hardware on the teensy side.

Since then, I got distracted by going racing in California and Christmas. My Teensy-to-canbus module has now arrived but I haven't yet tried to get things connected again.

I'm resyncing my git versions right now - I'm planning to sync to the 1.12 version of the app and I'm thinking of updating my RCP firmware to r/2.13.0 unless you recommend against this. This would be my first firmware update, so I'm tentative, but I saw some CAN mapping fixes have been added recently.

Recommendation? Thanks.