Megasquirt to Cluster VSS Signal
#1
Megasquirt to Cluster VSS Signal
Long story short, I no longer have a Miata trans or VSS in the trans. I have speed in the MS3 for traction control purposes and I'd like to send a signal to my NB cluster to have the needle move again and the cruise control function.
I know:
Speed input to the cluster is AC sine wave on two wires
I can only pulse an output to ground for speed from the MS3
Just hooking an output from the MS3 to one of the wires of the speed input won't work
I don't know:
How to emulate the AC sine wave with just a switched output
If the cluster can accept a square wave DC signal if I use a pull up resistor
Anyone have any insight or suggestions?
I know:
Speed input to the cluster is AC sine wave on two wires
I can only pulse an output to ground for speed from the MS3
Just hooking an output from the MS3 to one of the wires of the speed input won't work
I don't know:
How to emulate the AC sine wave with just a switched output
If the cluster can accept a square wave DC signal if I use a pull up resistor
Anyone have any insight or suggestions?
#3
The VSS outputs a zero-centered sine wave signal that increases in amplitude and frequency as the speed increases.
I'd bet the odometer unit will take a square wave just fine, but you may need to make it cross zero? Depends how it's triggered. For some reason I recall feeding it with a function generator as part of testing my cluster and it worked fine with a 0-12V square wave.
Definitely worth trying with a pull up to switch between 0 and 12V. I used to have some captures of an oscilloscope readout of the waveform but I can't seem to find it right now.
I'd bet the odometer unit will take a square wave just fine, but you may need to make it cross zero? Depends how it's triggered. For some reason I recall feeding it with a function generator as part of testing my cluster and it worked fine with a 0-12V square wave.
Definitely worth trying with a pull up to switch between 0 and 12V. I used to have some captures of an oscilloscope readout of the waveform but I can't seem to find it right now.
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