Speed Sensor Genboard Hardware modification

[Sprocket]

Do I go with this? http://195.159.109.134/vemsuk/forum/index.php/topic,717.msg7413.html#msg7413

Or with this? http://www.vems.hu/wiki/index.php?page=MembersPage%2FGergelyLezsak%2FAssemblyThreePointFive

I dont want to damage the processor. Its the only chip I haven't damaged yet :-\

[SamSpade]

The conditioning circuit depends on what type and where you get the speed signal.

If the speed signal is from an ABS wheel sensor or the rear differential the circuits will be different.  Also, in some cars the speed sensors go directly to the instrument cluster or ABS unit.  They then send out a cleaner processed signal for use by the ECU, cruise control unit and other boxes.  That would be the better option.

[MWfire]

with first solution, you can't kill CPU with 20V or more.
But first solution works only if you speed sensor is open coletor or has 0ohm(short) impulses.

[Sprocket]

Ah ok

I do not have any speed or wheel sensors, Its a Mini :D But I do intend to fit a hall type sensor using the aux 5v supply, sensor ground, and signal. What circuit do I need for this type of sensor?

Not sure where I am goung to install this sensor, But i was considering splicing it into the speedo cable some where, perhaps at the gearbox. I do intend to use a set of digital bike clocks in the not to distant future. I know there are other solutions for speed sensors, but Im looking for direct drive off the gearbox.

[MWfire]

for hall use
http://195.159.109.134/vemsuk/forum/index.php/topic,717.msg7413.html#msg7413

[multiplex]

I'd like to get this going, but don't want to loose knock.  Is this still the case? Wondering why, figured it would just disable PS/2?

[Sprocket]

for hall use
http://195.159.109.134/vemsuk/forum/index.php/topic,717.msg7413.html#msg7413

Thank you :)

[MWfire]

I'd like to get this going, but don't want to loose knock.  Is this still the case? Wondering why, figured it would just disable PS/2?

knock has separated input from speed sensor(PS/2)

[multiplex]

i have a little box that converts / divides my ABS sensor into a signal that can be used for my speedometer.

it has an extra 'digital' output which i'm planning on using for VEMS.  however its a 0-12 volt signal, and occasionally reads out 20 volts. Not sure how or why (usually when vehical is at rest).

i'm planning on using an optoisolator - feed in the signal, and feed the output to vems. since i have the PS/2 connector, i figured I'd also grab power from it to power the isolator.

Does this sound like a good solution?

[MWfire]

You can use that solution for test
http://195.159.109.134/vemsuk/forum/index.php/topic,717.msg7413.html#msg7413 without R4(dont connect to pin1(+5V).
Inevitable put 4.7V or so zener diode.

BTW that is pinout for vems connector near procesor, not ps/2 connector.

[Sprocket]

for hall use
http://195.159.109.134/vemsuk/forum/index.php/topic,717.msg7413.html#msg7413

Just a quick question about that schematic. The capacitor, is there one or two capacitors? the schematic lables show two capacitors but the diagram only shows one ???

[MWfire]

One capacitor. 1nF or 4.7nF or 10nF. So far i thnink 4.7nF is the best.

[Sprocket]

You can use that solution for test
http://195.159.109.134/vemsuk/forum/index.php/topic,717.msg7413.html#msg7413 without R4(dont connect to pin1(+5V).
Inevitable put 4.7V or so zener diode.

BTW that is pinout for vems connector near procesor, not ps/2 connector.

Just worked out that the speed sensor for the bike clocks im using is infact 12v pull up on the clocks themselves.

Do I need to follow the above, and leave the 5v pull up on the board off?

Do I need the 4.7v zener instead of the 5.1v?

thanks again

[MWfire]

you can remove pullup from board(5V), a you can put 4.7V zener diode