I put a bit more time into this at the weekend, changed the layout slightly (lost the T trip box, added speed) and now the trip meter values are live:
For those of us with LPG, there's a connection for the LPG solenoid so it can sense when you're running on LPG or petrol and update the P or L trip accordingly. Should make it easier to keep track of expected range etc. The sense line is just 12v so maybe it's of use for an aux fuel tank hooked up to the change over valve as I know some aux tank gauges are not very reliable!
Tapping the P / L box gets a screen to reset them:
Tapping the Speed box gets a screen with some options (I need to work on the colour scheme though it's not as illegible as it looks) where you can choose between 2 stored calibration values (for different sets of tyres) and kph or mph display (changes trip units as well).
I've still got to add the code for changing the calibration values, either by entering a known value, or driving a known distance and letting it count the sensor pulses. I've wound the signal generator up to see where the accuracy starts to fall off and really it's solid up to 500kph and then a small error creeps in so at 823kph it's +- 0.2 kph but I can live with that
Tapping on the A/B trip box will switch to a trip meter display, still to be coded, where you can perform all the usual trip meter type functions.
Thought I'd keep you posted on the direction it's heading in.