Monday, December 2, 2013

Intelligent shift light in July 2013

The intelligent shift light is practically auxiliary hardware for my ECU monitoring software.
It is very hard to look at the monitor and concentrate on the shift light graphics to appear while revving the engine sky high. Therefore I came up with this idea of intelligent shift light.
The reason why I call it "intelligent" is because of the principle how it works. In conventional shift light system the light lights up at certain RPM point regardless of gear. My shift light lights up a preset amount of reaction time before reaching the set RPM point, in my case before reaching the rev limiter at 8700 rpm.
This means the shift light will light up for example 0.3 sec before reaching the 8700 rpm. This translates into about 8000 rpm in 1st gear, 8400 rpm in 2nd gear, 8500 in 3rd gear, etc. This is the way how to utilise the full rpm range and engine power efficiently and translate it into the max possible acceleration. The RPM point is calculated on the fly, approx. 20 times per second.

The hardware consists of simple circuitry which translates the shift light warning graphics from software into a LED light emission. Having the LED in the middle of dashboard cluster makes it very easy to spot and react to. The circuitry consists of one high brightness orange LED, few resistors inc. photoresistor, potentiometers and transistor. The photoresistor adjusts the resistance according to the lightning condition, which makes the LED emit less intense light, thus avoiding blinding my eyes during night driving.

Shift light circuitry.
The circuitry is basically an extension to my DAQ board for reverse gear input. The DAQ has the capabilities not only to sense the input voltage but also output 5V voltage to external circuitry on command.

Left: Unmodified DAQ          Right: DAQ with additional shift light circuitry.

Fortunately the LED mounting was not a very hard job to do. I just reused the middle mounting hole for fitting the LED.

The middle mounting hole is used for the LED to go though.
Then I had to drill just one small 3 mm hole for the LED to be able to go through and be visible on the other side.

3mm high brightness LED.
LED fitted.
View from the backside.

The photoresistor is mounted on the steering column cover. It senses the light intensity that is reflected from the dashboard cluster and the ambient light as well.

Mounted photoresistor.

The working of this shift light can be seen in this video:

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