Megasquirt, CAS, pull up resistors, Megastim, help?!
Posted: Sun Apr 14, 2013 12:41 pm
I'm posting this anyway, because typing it out actually solved the problem for me.... I'd attached one of the mod wires in the wrong place 
I've assembled a Megasquirt V3.0, with the MSII daughterboard, following various guides, and modifications. (ignore the missing Q16, its on order ;))
The idea is to run an MX5 cam angle sensor, so I've done the modifications found here to add the pullup resistors:
http://www.diyautotune.com/tech_article ... _miata.htm
The tach signal is assembled like so with the 12volt pull up mod connected to D1 (this isn't meant to be D1, its D5! and the reason it didn't work) (470ohm resistor connected to the 12volts)
The issue is, as per the diagram, the voltages? are they meant to be this low at the output of the optocoupler?
Output from the Megastim looks like this, measured at the "input" of R12:
But then the "output" from R12 looks like this?
Is it meant to be that incredibly low? or is something loading it down?
And finally, the output from the optocoupler:
Which is meant to change between high and low.... I'm not sure how high "high" is, but I'd assume its meant to be higher than 72mv?
Any assistance would be fantastic? is there something stupidly obvious that I'm missing here?
Thanks!
I've assembled a Megasquirt V3.0, with the MSII daughterboard, following various guides, and modifications. (ignore the missing Q16, its on order ;))
The idea is to run an MX5 cam angle sensor, so I've done the modifications found here to add the pullup resistors:
http://www.diyautotune.com/tech_article ... _miata.htm
The tach signal is assembled like so with the 12volt pull up mod connected to D1 (this isn't meant to be D1, its D5! and the reason it didn't work) (470ohm resistor connected to the 12volts)
The issue is, as per the diagram, the voltages? are they meant to be this low at the output of the optocoupler?
Output from the Megastim looks like this, measured at the "input" of R12:
But then the "output" from R12 looks like this?
Is it meant to be that incredibly low? or is something loading it down?
And finally, the output from the optocoupler:
Which is meant to change between high and low.... I'm not sure how high "high" is, but I'd assume its meant to be higher than 72mv?
Any assistance would be fantastic? is there something stupidly obvious that I'm missing here?
Thanks!
