Understanding speedometer signal

[bymannan]

Hey all,

I've upgraded my SurRon with a far drive ND72530 controller and I'm hopping to preserve the original speedometer. However, I don't think it uses standard signal.

The controller has two wires for speedo connection, Phase wire and analog wire. Phase wire can also be configured as a Pulse or Isolated Pulse in the settings.

The original Surron speedo seems to be a volt meter, i.e., inputing 3v will display 20kmh, inputing 6v will display 40kmh.

I'm not sure how the analog wire works, when speed is 0 it gives out 0v. When speed is increased it shows around 0.8v and as the speed increases the volt will go down by around .01 steps. Perhaps its resistance based?

Ideally I'll be able to convey a way to convert one of those outputs from the controller to volt output that the speedo can understand.

Can anyone share some info on how this all works?

 

[aironas7]

Hello. Im trying the same thing. How did you input 3volts etc to the surron speedometer? using what? Theres a + and - wires for the speedometer and then a third wire to measure speed/volts? how does that work and what do i use to input volts. tried to connect a regular 5v battery to that extra wire and speed would not show up still.

 

[quake-lo]

Hello. I have replaced the original, broken controller in my scooter-car (3 wheels kind) with a fardriver. And everything works fine, just not the speedometer. The speedo in my case also turned out to need dc voltage as the input, which is converted to speed. I was just brain-storming that the fardriver's analog speed line could be for a DC or PWM signal. I could then use its output in combination with a DAC (if PWM) and an esp32 controller to get the voltmeter-speedometer to work. But I tried with a multimeter and oscilloscope, and I didn't get any readings that made sense to me. So right now my "temp" solution is just to use a GPS speedometer, which is not bad.

I'd just like to know if using a volt-based speedometer is somehow possible with the fardriver controller? Or if I should just drop the matter. Of course I searched a lot, read the fardriver manual - and I read a lot in this forum. But at least 'I' cannot find an answer to this question. I did learn that you can make your own speedometer using an esp32/arduino microcontroller using bluetooth/serial. And like a GPS speedometer, it is a kind of alternative solution.

Thanks. Also, I am not an expert by an means. )