[Diy_efi] Data Logger CPU schematic and C for review

Steven P. Donegan steve
Mon Feb 5 01:36:14 UTC 2007


Thank you for the pointer - I may add the device to my design...

On Sun, 2007-02-04 at 16:44 -0600, Robert W Hughes wrote:
> >> What would also be interesting would be the ability to directly
> >> > drive analog gauges. Since a lot of people lose some or all of the
> >> > dash gauges when going to a non-OEM MCU, it would be nice to be
> >> > able to restore this functionality. I don't know exactly how this
> >> > would be done and it certainly is dependent on the vehicle but
> >> > some type of PWM or stepper motor controller would cover some
> >> > cases.
> > 
> > Reminds me...
> > 
> > I've toyed with the idea of using RC-servos to do the needle
> > positioning on stock gauges. The servos are controlled by pulse
> > width and (I understand) will lock when they get no further signal.
> > Even removing power leaves the servo locked in position.
> > 
> > This by-passes the need to fake various types of signal and allows
> > for other interesting analogue gauge functions to be programmed.
> > Also, pulses only need to be sent to the gauge when the indicated
> > value is to change.
> 
> Most late model cars use air core meters which can do 90 or 270 degree 
> or more sweeps. Check out the Phillips driver SA5778D at 
> http://www.ortodoxism.ro/datasheets/philips/SA5778D.pdf  for an idea of 
> what is involved. This chip accepts a serial bit string to drive two 
> 90deg meters and one 270 with .35deg resolution and could probably drive 
> the instruments in a car panel with whatever you wanted to digitize and 
> send out. I think most manufacturers are using something like this in 
> their panels now to cut down on wiring and connector pin count.
> 
> --
> Robert W. Hughes (Bob)
> BackYard Engineering
> 29:40.237N, 95:28.726W or perhaps 30:55.265N, 95:20.590W
> Houston, Texas "The city with too much Oxygen"
> rwhughe at oplink.net
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> Subscribe: http://lists.diy-efi.org/mailman/listinfo/diy_efi
> Main WWW page:  http://www.diy-efi.org/diy_efi





More information about the Diy_efi mailing list