MoTeC Global Forum

Hi all,

We are running a brake over travel switch in our fsae car, when the switch is hit it kills ignition and fuel. We are doing this by using a digital input and using the 31- stop switch option in the ecu that cuts fuel and ignition.

Our brake over travel switch activates a relay and this sends a single 12v to the signal of the dig in on the ecu.

My question is where do we connect our 0v of the dig in?can it go straight to ground?

Thanks

The digital inputs will only work if switched to ground. They have an internal pull up to 5v. If you switch 12v into them they will not work.

If you need a switched signal that goes up to 12v you need to use a Switched Input and not a digital. A switched input still has a 5v pull up but you can set the trigr levels to be greater than 5v.

Hi Damien, I'm from UniSa (shark car, ran out of fuel 2010) and was wondering if you ran into any problems regarding fuel and spark cut in a BOT situation?

From what I can see in the FSAE rules (B7.3.3), the over travel switch needs to be implemented using 'analog' components. Recourse to programmable controllers or ECU is prohibited. I can see you're switching the signal via a relay ('analog') part but ultimately uses the ECU to cut fuel and spark - is this allowed in the rules?

We wire ours so the BOT switch relay was 'in-line' with the fuel and spark power relays so disabled directly without ECU.

Cheers,
Justin
Electrical Team UniSa FSAE