It's 31C today in Canberra (according to my car) and I had really given it a good work out to get the temps up to these:
"Spd" changes to "Tim" (flashing for 10 seconds) and shows the seconds to two decimal places if you do a 0-100 time under 10 seconds. I've seen Bst go as high as 15 too (though mine is tuned).
Here's a circuit diagram and component list (components touching each other mean they are connected - and as I've got two screens I can show the front and back at the same time - you only need one of course):
I'm not entirely happy with "voltage" as it always shows "XX.0V" - 12 when the car is not started, 13 or 14 when it is. I don't know where the decimal place disappears to, in my tests it should work - so I don't think the car gives the value to that precision despite being able to.
The attachment is a zip file with the microcontroller source code (with no warranty!) and the compiled FDIM software program (which is tested only on a non-sat-nav unit). I'm concerned about using a 5v microcontroller on the 3.3v FDIM - the resistors should protect it, but I need to do more research on the Nano before I try. A non-sat-nav FDIM only uses the Nano's TX output, which I have tested as being good with those resistors - it's the Nano's RX input that I'm concerned about, since the USB chip underneath is pulling it up to 5v.
When I do test on my FDIM, I'll need to edit the navi package startup script:
Changing u5 to u4, and starting the gauges before "wait /dev/ser5" is run...
devc-sermx1 -u5 -F -b115200 -c66500000 0x43fb4000,47
to:
devc-sermx1 -u4 -F -b115200 -c66500000 0x43fb4000,47
I've been running this from the debug console:
devc-sermx1 -u4 -F -b115200 -c66500000 0x43fb4000,47 &
For my bench testing (& on the end makes the program run and the debug shell come back right away).
The FDIM gauges software opens ser4 and creates a new device ser5 (so it should in theory still send the sat-nav chips output to the right place).
Anyway, I'm pretty happy with the LCD (standalone) mode and maybe people with an FG (I) or FGX will get use out of this? Rename the .txt file to .zip of course - I hope I can break the forum rules on this file in this case?