Autosport Labs

I have two questions.. I would like to run some resistance-based sensors to RaceCapture. Specifically, these are stock Volvo VDO sensors (oil pressure, oil temp, coolant temp, fuel level, etc) that are currently running to the gauge cluster. I actually have some of the resistance maps for these sensors somewhere, and I have read the instructions on running resistance sensors to the RC analog inputs w/ a pullup resistor to 5V Ref.

Here's the question - is is possible to keep these sensors wired to the gauge cluster and also wire them to RaceCapture? We have the Realtime Data package and would love to have cluster data in the pit, but I do not want to lose our cluster gauges in case we have a problem getting the data in the pits.

Second question - we have MegaSquirt in the car. Has anyone gotten outputs from MegaSquirt tied into RaceCapture? RPMs would be good to start with, but I would love to see some more advanced data from there too.

Thanks!

Hi Vinz,

the recommended route is to have independent sensors for your data acquisition, just like the ECU (megasquirt) has it's own sensors isolated from the gauges as well.

You can try to piggy back on the gauges by measuring the voltage on the gauge terminal throughout it's range. e.g. low to high pressure, low to high temperature, etc. If you're piggy-backing on the gauge then you will *not* want to use the 5v voltage reference from RaceCapture/Pro. Use the 5v voltage reference only with dedicated sensors.

If you have a tach *output* wire from the megasquirt then you can feed that into the pulse input of RaceCapture/Pro. Be careful the wire you're tapping into is not connected to the ignition coil; this signal has a 500v voltage pulse that RaceCapture/Pro was not designed to handle.

If you're unsure, post some diagrams on how you have your megasquirt wired up.

As far as grabbing a data stream from the Megasquirt, that would be a great user contribution. It would probably be integrated into an expansion module (the RJ45 plug next to the terminal block).

Brent,
Good deal, thanks for the info. Do you have some example Analog Port Configuration settings for this kind of setup?

Hi,

So which analog port configuration do you mean? with a dedicated sensor?

We're going to be normalizing our recommended set of sensors, soon - temperature, pressure, coil interface, etc. to make it easier for people to integrate RaceCapture/Pro into their vehicles. Watch for a blog post on this soon.

No, I mean for piggybacking to the cluster sensors. Current plan is :

Analog 1 - Coolant Temp +
A2 - Coolant Temp -
A3 - Fuel level +
A4 - Fuel Level -
A5 - Oil Pressure +
A6 - Oil Pressure -

Hi,

Sorry, not quite following your +/- designations. the analog inputs are single ended, meaning they are referenced to the ground of the unit (the terminal block pin 1). So Analog 1 is for the first sensor, Analog 2 the second sensor, etc.

Ok.. these sensors have separate ground wires in the harness going to the cluster, but looking at the diagram, they are shared further back. I'll just wire the + gauge wire to an analog port and set up the sample rate and measure through the range as you suggested.

On a totally unrelated note - I was able to get RaceCapture working with the Realtime Data module while powered by a laptop USB port. The wiki says it won't work, but it seems okay so far to me for testing purposes.

We had a dell laptop running linux in the back of this car for a few races gathering GPS data. Thanks for making an awesome product to replace it!

Awesome! Please do (I mean really do) share the RaceCapture/Pro project with your extended communities as we have a next-to-zero advertising budget. In any case, we'd rather spread the word through happy users! Thanks again, and we totally want to see pictures of your car/setup when you get it going further!

So It's kind of sketchy with USB power - I've seen it work under some cases too. USB is only 500mA at 5v - the cellular module will burst up to 2A- it takes a lot of juice. There might be environmental considerations, like if you're close to a cell tower and the cell module doesn't have to crank up the transmit power-- things like that.