Sunday, December 13, 2009

Making sense of Spaghetti

After receiving the engine, gearbox, loom etc a couple of weeks ago I decided that it was about time that I got stuck in to doing some work on the project. Having received my ODBLink on friday and also some wiring schematics for an RX8 earlier in the week I decided that the first place to start was the big mess of wiring that I have which looked like this...

After a few hours of looking over the wiring schematics and sifting through the big mess of wires I was able to untangle them somewhat and it started looking a little more reasonable. I identified about 40% of the plugs in the loom, still a bit to go though... Without the schematics though things would be near impossible, I guess thats one the issues of not taking the loom out of the car yourself.

This is what 20 odd pages of laminated (they should last the build laminated) schematics looks like. And this isn't all of them!

I also wanted to see how the new OBD tool I bought wworks but because I dont have a key for my loom I can't really talk to the RX8 ECU just yet. So I took the opportunity to borrow my fiance's freinds car while they were out looking for dresses and see what sort of data I could get from the CAN bus in her Mazda 2. I was a bit worried the tool I bought might not be able to give me the underlying CAN data from the car but after a bit of searching I found a great pdf for the ELM327 chipset used in the ODBLink. After a few 'AT' commands sent to the device I was able to receive the raw CAN data which I am going to write some basic software to interpreret. For the time being I am just using hyperterminal in windows.

Once I've written some .Net code to interperet the CAN frames I will post the source up here...

Thursday, December 3, 2009

S15 Sold, Engine Delivered

Well after about five weeks and very few actual shoppers and plenty of time wasters I've finally sold my S15. And not a moment too soon, next week I need to make final payment on my clubman so everything is running smooth at the moment.

I also had the RX8 engine and parts delivered yesterday. This on the other hand was not the smoothest of deliveries. Firstly they tried to deliver it on Tuesday without calling me first so that I could arrange to be home to unpackage the 320kg box off the truck. So I arranged for redelivery the following day between 9-12am. It didn't arrive... So after about 5 phone calls to TNT the package arrived at 5:05pm. A wonderful day of daytime TV it was...

I've also been looking into how I am going to tackle the task of wiring everything up. I have the majority of the electrical components from the donor RX8 and I learned recently thanks to a blog named Madox.NET the some Mazda's (RX8 included) run a CAN network that allows all of the electronics in the car to talk to each other much like computers do on a normal network.

With some specialist devices such as OBDLink a normal computer can also talk on this network through the cars diagnostic port. This port will allow me to do two things, firstly I will be able to check error codes from the engine ECU which will help me to pass emissions and trouble shoot setup issues. Secondly I will be able to intercept signals that would normally go to the dash for things like engine revs, speed, trip computer etc

What I am proposing to do is instead of using a dash from a car or motor bike is to instead use an Asus EEE PC T91 tablet PC with the CAN hardware and some software I will develop myself to create my own dash. Because I will be getting data directly from the Mazda sensors, some of which isn't normally displayed to the driver I will be able to show all ADR required gauges and more. What's great about this is it will be far cheaper and easier than buying seperate gauges and having to install new sensors for them. Plus, if I can have a whole range of dash designs and flick through them with a touch of the screen and adding warning lights/buzzers will be a matter of a few lines of code rather than a heap of wiring/cutting etc...

Here is a sample screen shot of a RX8 style dash design written in .Net using Dundas Gauges, I also added a basic three stage shift light that lights up yellow, then organge then completely red when it's time to shift.