Older BMWs have a fuel consumption gauge on the dash. Someone has already implemented a standalone boost gauge for this, however it should be a simple extension of VEMS to handle this gauge directly
A Canadian fellow developed his own circuitry to control the meter:
- Forum discussion http://www.e30tech.com/forum/viewtopic.php?t=35635
- 1st video http://www.youtube.com/watch?v=S5KwL2DUkro
- 2nd video http://www.youtube.com/watch?v=-6KX1V0j8bk
A thought about the scale of the econometer is that it goes from 0 to 30. That could mean these pressures:
- 0 = 0 kPa absolute vacuum
- 10 = 100 kPa atmospheric
- 20 ..
- 30 = 300 kPa or 2 bar boost at sea level
Data from this forum thread: http://www.pure-pf.com/phpBB2/viewtopic.php?t=19563
0 = 0,00 V
10 = 0,58 V
20 = 1,10 V
30 = 1,58 V
To max out the needle you need 1.75 Volts to pass the max marking.
A really basic and not entirely useless feature. Could possibly be designed to ouput other things. Could need a table, or a good approximation algorithm.
- High impedance input assumed..
- What is a good pull-up voltage source?
- Stepper output goes from 0-12 Volts:
- can it switch fast enough
- accurate for 0 up to 1.75 VOlts using PWM?
- Can a 5 Volt output be used as pull-up when a regular output is used?
- Hall sensor output (if not used?)
- TPS +5V source ?
- We have existing BOOSTGAUGE code for Audi instruments. Why not using that one?