openinverter forum

I’m at the point of integrating the Tesla SDU with the Honda S2000 electronics, specifically the dash cluster.
I’d like to display speed (of course), amperage (on the tachometer), state of charge (fuel gauge) etc.

First step is converting the OpenInverter's RPM output to the S2000's Vehicle Speed Sensor. I haven't looked at what signal the OpenInverter board outputs but I expect it's a square wave based on the trigger wheel in the SDU (happy to be corrected).

The S2000 dash cluster accepts a square wave signal and counts the frequency. Surprisingly it doesn't seem to use a 0 origin but has an offset for about 100hz
So I assume the task is to read one frequency and convert to another. I'm looking at an Arduino board to do the conversion. And I have seen boards like the AD9833 to generate an output frequency. Not sure how to read the input at this point.

If anyone has any input or direction it would be appreciated.

Hi
Unfortunately the sdu board doesn't export the pwm signal so you will need something external to drive the cluster

johu wrote: ↑Fri Mar 01, 2024 6:44 am Unfortunately the sdu board doesn't export the pwm signal so you will need something external to drive the cluster

Really? How are others deriving a speed signal?

Over the CAN bus and then some Arduino converts it to variable frequency.

Ok. In that case I need to catch and interpret the canbus packets and input to the arduino. Be interested in any links to those that have already done this.

Take a look at EVTV's CANDue board, it has a well established library and it can send and receive CAN messages. Effectively it's a Arduino Due with two CAN channels.

On the SDU side you will need to configure the outgoing CAN messages via the web interface. On the Arduino side you'll need to tell it to receive those messages and interpret them into the signal the dash needs. You'll have to do some math in the code using the SDU gear ratio and your tire size to determine speed based on RPM.

If you're not married to the stock dash, Speedhut has a line of EV gauges and they tell you what messages you need to set the SDU to send. I like the set I bought, but did learn that there has to be something else on the Bus, or the SDU won't see any confirmation of its messages and thus stop sending them. The Speedhut gauges don't send any sort of confirmation (presumably to not disrupt OEM cars) and the SDU needs to see something else on the bus to keep sending messages.

I just ordered some MPC2515s to play with.

I'll look into the CANDue board too.

P.S.Mangelsdorf wrote: ↑Fri Mar 01, 2024 1:14 pm Effectively it's a Arduino Due with two CAN channels.

There is also eeprom needed for effective DUE use, wich led me to design my own shield that goes over DUE board and has 2 CAN chips, uln2003 chip for outputs and two small relays for using stronger contactors.
Input power is protected by a diode and there are several pads for pwm transistors with 12V and 5V pullups.
Finally there are 3 analog inputs with resistor divider.

I may have some boards left for populate by hand if you want to build yourself. Or i can... PM me.

arber333 wrote: ↑Fri Mar 01, 2024 2:48 pm I may have some boards left for populate by hand if you want to build yourself. Or i can... PM me.

Cheers. I'll see where I get to with Arduino and get back to you.

johu wrote: ↑Fri Mar 01, 2024 6:44 am Unfortunately the sdu board doesn't export the pwm signal so you will need something external to drive the cluster

I've got the output side of the project working:


About to start work on the input (Canbus) side.

But anyone know what this is?

Outputs from LDU used on my Porsche here:

viewtopic.php?p=49997#p49997

Boxster EV wrote: ↑Tue Apr 30, 2024 12:10 pm Outputs from LDU used on my Porsche here:

viewtopic.php?p=49997#p49997

I didn’t see anything about the RPM Signal

EVS2K wrote: ↑Tue Apr 30, 2024 12:45 pm I didn’t see anything about the RPM Signal

That’s transmitted from the OE ABS pump on the Porsche so it sits outside of this scope (but on the same 500k bus).


Edit: no it isn’t. The speedo takes can messages from the ABS unit.

EVS2K wrote: ↑Tue Apr 30, 2024 3:30 am But anyone know what this is?

It was never brought out to this pin. But it's not very useful anyway since it runs at a fixed frequency and variable duty cycle.