VEMS Community Forum

Technical => Wiring & Sensors => Topic started by: dnb on May 21, 2012, 12:58:13 AM

Title: Wheel speed maximim frequency?
Post by: dnb on May 21, 2012, 12:58:13 AM
Has anyone found the wheel speed signal can't cope with a frequency higher than 1096Hz?  On my bench test rig I can get the wheel speed to function, but unless I limit the input frequency to less than 1096Hz I get aliasing effects followed by zero speed displayed.  The divider and pulses per 100km/h work as expected.

The divider doesn't help because it's implemented after the pulse counter stage, so it just reduces the range of speed displayed in VEMStune.

I really need something to work to at least 4kHz.  Am I missing something in the config or do I have to build a hardware divider for the input?

Thanks
Title: Re: Wheel speed maximim frequency?
Post by: [email protected] on May 22, 2012, 11:53:04 AM
I would hazard a guess that its the max speed you'll see as the speed sensor is connected to the IO that was used for keyboard input, I'm guessing a hardware divider is required.
Title: Re: Wheel speed maximim frequency?
Post by: GintsK on May 22, 2012, 08:12:12 PM
Did you scoped input pin? Could be that low-pass filter cut amplitude. Just a guess.

Gints
Title: Re: Wheel speed maximim frequency?
Post by: dnb on May 22, 2012, 10:47:25 PM
I did scope the input to the ECU.  It remained at a good signal level all the way to 5kHz.  I'm using the speed signal to control the epas system too.