I need a solution for speedometer on Dashbox

Best would be if it could handle pulse, but it can only handle analog input.

Is there anyone who have a good solution?
tried using frequenzy to voltage adapter but the speedo is jumping too much.
tried an tachogenerator, 7v/1000rpm , better but still, needle is jumping.
any answers please.

I think its best to contact SPLeinonen about their hardware capabilities.

They recommended to use the digital to analog device.

Is there no way to have realdash handle a pulsing inpt as speed?

I believe that would require changes to Dashbox firmware, which is out of scope of RealDash.

Attached is a schematic which I devised for exactly this task. Also attached is a veroboard layout. It should work fine with a needle gauge in RD. My VSS / gearbox / road-wheel-size combination gives 8000 pulses per mile. You’ll need to alter R4 / C4 values if your car is much different. The output needs to be less than 5v to suit the Dashbox analog inputs.

Just for interest, my situation was a little more challenging as my dash uses a text gauge for mph which brings an additional problem that no matter how “smooth” the analogue signal there is still jitter in the gauge output whenever the speed is exactly on the integer boundary e.g. if the speed is exactly, say, 60mph the display will flicker between 59 and 60. I had to arrange for the display to refresh no more than once per second.

Also just for interest, part way through developing my dash I abandoned the Dashbox because it did not have quite enough digital and analogue inputs for all the additional sensors I planned to fit to my car. I could have worked around that with a multiplexer in front of the Dashbox but but with that in addition to the mph interface I felt my project was getting a bit messy, so I built my own Arduino Nano + 16 channel mux “dashbox”, which also allowed me to provide two pulsed inputs.

Hope some of this is useful

1 Like

thanks, I´ll try it.

Could this be a solution to expansion?

NMEA 2000 is compatible with the Controller Area Network (“CAN Bus”) used on road vehicles and fuel engines.

NMEA2000 is the CAN protocol standard for marine use. Unfortunately the NMEA2000 documentation is proprietary and not available to public.

how did you get it to refresh every 1sec?

I’m in the process of replacing my Dashbox with a home-made equivalent which calculates MPH from the period between VSS pulses and will also take care of smoothing / refresh rate, however I’ve dug out the attached from the previous, Dashbox-based, dash which more or less shows how I used a trigger to get the once per second refresh.

I hope that gives you enough.


1 Like

Thanks, I´ll try it.

1 Like

Is there any alternative to dashbox?