2001 C4 project car

Here is one I prepared earlier.



MC

I'm going to have to buy some more hats as the one I currently have has already been taken off to you.

Damn fine work MC :worship:

Agree, this will be brilliant when finished.

Now reading correctly scaled RPM in.



MC

Is that labview or labwindows or something?

wasz said:

Is that labview or labwindows or something?

Click to expand...

It is the Live Monitor software for Race Technology data loggers. I'm using the Race Technology serial data format to output from the dashboard for data logging.

MC

I have been playing around a bit more with the electronics. The new engine which will eventually go in this will rev higher than the standard engine. As such, the red line on the rev counter will need to be moved. That in itself isn't a problem as there are companies which will print new fronts for the gauges. What is a problem though is that I want to change the scaling on the rev counter so that the maximum value shown is also higher. I might even decide to have a non-linear rev counter. I.E. 0 2 4 6 7 8 9 or whatever takes my fancy.

I don't normally detail any of the electrical/electronics stuff I'm doing, but just on the offchance that anybody is interested there are some details here.

The circuit intercepts the engine speed signal from the ECU and generate a new signal to go the rev counter. This will sit inside the instrument binnacle and is part of the same circuit which is rescaling the coolant temperature gauge and enabling it to show oil temperature.
The signal from the ECU is a 12v square wave with a 50% duty cycle. There are three pulses per engine revolution. This signal goes in to a capture input on the processor and the time between rising edges on the signal is measured. This time is then converted to an RPM value, this value can be output on the serial or CAN port. The value for the RPM is then translated to a required output time and used to generate a new PWM signal for the output signal to the rev counter. Because of this break between the input and output signal I can rescale the values before they are output. The rescaling will be done using a lookup table, something like this

Input Output
0 0
4000 2000
9000 8000

The firmware will take the required transmission value and then do a linear interpolation between points in the table. So a value of 3000 for the actual engine speed would be output as a value of 1500.
It will be really easy to change the scale, and I could have scales selectable by button press if required (just in case you wanted to show an artificially high or low engine speed).

The other feature I wanted to add was a peak RPM storage and recall. This works using the trip reset button. a short press on this will cause the rev counter to change to show the peak RPM for a couple of seconds. A second press when the value is being displayed will cause the peak value to be reset. To actually reset the trip counter requires a button press of 0.5s or there abouts, so the operation is not affected.

This is demonstrated in this video. The box on the left is a signal generator, outputting a value in Hz for the engine speed. The box on the right is a timer, this is measuring the output pulse duration. So a shorter pulse is higher RPM. I wind the RPM up and then down, then show the peak RPM value on the output a couple of times, then reset it and repeat. It will be more obvious when I hook it up to the rev counter, but you get the idea.



MC

Love this stuff I used to do a lot of reverse engineering and hacking things for other purposes a lot, not cars though.

Whoosh!!

Straight over my head all that electronics stuff but (as if we didn't know already) you're a clever bloke Martin.

The info from yourself and also the things I read from Dyno Mike make me wish I'd worked harder to find my niche in life.

Truly brilliant knowledge and attention to detail. :worship:

More playing around with the electronics.

I have an output to drive a solenoid to turn a centre radiator on and off, this is currently set to come on at 95 degres and go off under 90.
I will have an indicator on the dashboard to show when the oil temperature rather than coolant is being displayed, using an unused indicator light. I have set this so that when showing coolant temperature the light will flash if the oil temperature is below 80 degrees to show that it isn't warmed up yet. After going off above 80 it will come on again if the temperature drops below 75 degrees. It won't flash when showing oil temperature.

I added in dual scaling for the rpm so I can have a compressed low end scale and tested that. It is currently set to have mullitple scales but I haven't implemented switching them from the buttons. I have also tested the wheel speed measurement, but it isn't scaled yet.

Using a signal generator I measured the required frequencies for the display.



I have added a shiftlight output to the circuit. With engine and vehicle speed I can program different shiftlights in each gear. I am not yet sure exactly what I will drive with the shiftlight output.

MC

Wheel speed now being read.



MC

The newer 911's have a multi-function display to the right of the rev counter - why not simply replace the clock faces with LCD/OLED displays instead? That way they can be reconfigured on the fly, and you never need to have new faces printed!

I really wanted to keep the instruments looking pretty much standard. I could have easily added an external display but they don't look good. My skills are not up to neatly integrating an LCD display in to the standard instruments.

MC

MisterCorn said:

My skills are not up to neatly integrating an LCD display in to the standard instruments.

MC

Click to expand...

I don't think anyone on here will believe that for a minute :worship:

We can agree to differ on that, I won't be attempting it anyway...

There has already been progress in the bodyshop, which has taken me rather by surprise TBH.

Rust under the sill cover sorted out.


Rear wiper delete.


Arch rolled


Sill sorted out




There is some more work to do on the jacking points, then he will take a look at the other side.

MC