RPM output with EDIS
flak monkey - 25/3/09 at 05:55 PM
Where do you take your rpm signal from with edis?
I have heard that pin 2 is an rpm output on the edis unit, but of course there is no wire connected to that in the plug!
My dash is programmable to take either a high voltage rpm input eg from a coil, or a 12v square wave input from an ECU. So what are my options?
I could (and probably will eventually) connect the MS to my dash via the serial link and use the MS to drive my dash, but while its being tuned I
obviously need the serial port for the laptop. 
Cheers,
David
[Edited on 25/3/09 by flak monkey]
blakep82 - 25/3/09 at 05:59 PM
hmm, good question that is. i noticed that too. the only thing i could think of was, perhaps the cars from which our edis came from didn't have
rev counters fitted. but you'd expect the edis would all be the same.
i've got megajolt, and thats got an output on it i think
flak monkey - 25/3/09 at 06:07 PM
You can configure rpm outputs from the MS unit, but having looked at the options its very confusing.
All I want to know is how you get an RPM signal from MSnS Extra with a V3 board... 
omega0684 - 25/3/09 at 06:21 PM
quote:
I have heard that pin 2 is an rpm output on the edis unit, but of course there is no wire connected to that in the plug!
pin 11 is the blocked off one, between 10 & 12 that go to the coil pack, pins 1 &3 are for the pip and saw, and pin 2 is the rev output i
connected pin 2 to the electronic input wire on the back of my rev counter and hey presto my rev counter was alive!
[Edited on 25/3/09 by omega0684]
paulf - 25/3/09 at 06:30 PM
I used the pip signal to drive my Smiths type tacho.The tacho output wouldnt drive it but when I connected to the pip signal it works perfectly.The
megasquirt can be conected to give a tacho signal but also requires a buffer transistor adding to drive the tacho.
Paul.
[Edited on 25/3/09 by paulf]
flak monkey - 25/3/09 at 06:31 PM
Thanks chaps, as always theres more than one way to do it!
matt_claydon - 25/3/09 at 06:34 PM
The first diagram in the MSnS manual should work for you:
I wouldn't worry too much about the resistor value, 1K should be fine. If you want a 5v square wave then use a suitable 5v supply from the board
instead of 12v for the top line. I would have thought 12v would be fine with your dash though??
Build the little circuit on the proto area on the V3 board and hook it to your chosen pin on the processor and one of the spare outputs on the DB37
connector.
I used this circuit to drive my tacho with success.
flak monkey - 25/3/09 at 06:44 PM
One bit I never grasped was connecting stuff to the processor on 'your chosen pin'. I didnt get into all the building of the MS so dont
really understand all the user configurable output stuff.
No doubt its very simple and it just hasnt clicked yet!
triumphdave - 25/3/09 at 07:13 PM
I had all sorts of issues trying to get a decent tacho reading,in the end i did the same as robocog above
matt_claydon - 25/3/09 at 07:16 PM
quote:
Originally posted by flak monkey
One bit I never grasped was connecting stuff to the processor on 'your chosen pin'. I didnt get into all the building of the MS so dont
really understand all the user configurable output stuff.
No doubt its very simple and it just hasnt clicked yet!
In the MegaTune options, there is a screen that lets you assign various funtions to 'spare' processor pins. If one of the external solutions
going straight to the EDIS works then I'd go for that though as it'll be much simpler. I was driving coils directly so had to go with ECU
control.
You could just drive the dash direct from the coil negative terminal, that's probably the most simple method. With wasted spark you get twice as
many pulses as some tachos expect, but I imagine your dash can be configured to take account of that (just tell it you've got an 8-cylinder for
example)
mediabloke - 25/3/09 at 09:11 PM
The tacho output from my mjlj was also jumpy.
Took a feed off the PIP line from EDIS: worked a treat - rock solid. 
flak monkey - 25/3/09 at 09:25 PM
quote:
Originally posted by mediabloke
The tacho output from my mjlj was also jumpy.
Took a feed off the PIP line from EDIS: worked a treat - rock solid.
Sounds like thats the best way to do it then I'll try that and see what happens