Additional inputs for MJLJ

eric_f · Post by **eric_f** » Thu Jan 13, 2011 6:22 am

Hey everyone.

I saw a post here and one of the posts was from brent saying

For those that would like to do firmware mods, there's also the AUX input on the board (not tied to the molex connector). That feeds a pin on the processor which can be configured as an Analog or digital channel.

Brent, can you, or anybody for that matter provide me some more info on this?

My thoughts are this: currently I have my MJLJ hooked up to my Arduino via serial and I'm able to read the data and display it on and LCD or whatever I choose to do. I am planning on using the Aux Input for oil temperature but I would love to be able to hook my O2 (lambda) sensor up to the MJLJ and then pass the info through serial to my Arduino. Since I'm using the MAP sensor, I would disconnect the TPS input pin in the molex connector, and jumper it internally.

I wouldn't do anything with the data on the MJLJ side, just pass through, it would help to simplify the wiring in my car.

Thanks so much

Eric

Post by **brentp** » Thu Jan 13, 2011 7:56 am

Hi Eric,

Yes, it will accept a 5v signal (would recommend conditioning / protection, there's a schematic snippet posted elsewhere)

On the V3 controller you will need to upgrade to the latest 3.3.x firmware so that the controller reads this port and presents it as the 'Aux' input.

eric_f · Post by **eric_f** » Thu Jan 13, 2011 3:54 pm

Thanks Brent

I looked for a schematic, but couldn't find one, I'll look again.

I've got a V4 rev C I do believe. So when I get this done, I'll have two Aux Inputs right?

Thanks again

Eric

NITROPIXIE · Post by **NITROPIXIE** » Thu Jan 13, 2011 5:48 pm

Hi Eric

I'm afraid there are no input pins left on the processor chip in order to jumper the tps input from the molex. The MAP sensor and TPS sensor both use the same input on the processor chip.

There is only 1 auxiliary channel and that has been provided for you. You could only use this as an Engine Temp input as you have or an O2 input, not both.

Hope this helps

Ryan

eric_f · Post by **eric_f** » Thu Jan 13, 2011 5:51 pm

Ryan

My plan was to sever the link from the TPS in the Molex connector, so it's no longer connected to the circuitry internally, it would then be passed over to the second input.

From what Brent said in the other post (maybe it's not relevant on the V4 boards?) there is an unused input in the processor that I could tie into. Doing that would get me the two inputs.

Eric

Funky Diver · Post by **Funky Diver** » Thu Jan 13, 2011 8:19 pm

Why don't you just pass the info straight to Arduino instead of linking it into MJLJ?

In essence, what I'm suggesting is take the info from the sensors that you have already identified (and any others you can think of, ambient temperature for example) and create conditions in Arduino that will output to the MJLJ?

Just a quick example... 02 reading too high and temperature normal... change advance curve slightly... that voltage would be say a low one on the Aux in.... With a bit of intelligent programming I'd imagine that it would work quite well?

Just a thought

eric_f · Post by **eric_f** » Thu Jan 13, 2011 9:02 pm

That's more or less how I've planned to do it up until now. I just thought if I could feed mjlj directly I would have less wiring to do. Also I'm thinking one day going metasquirt (unless Brent comes up with fuel injection

) and it would simplify the Chang overfor that too.

After re-reading Funky Divers comment I Undersfand differently. Arduino reads all input and can send a signal to the mjlj. Interesting. I like it.
It sill wouldn't work for the metasquirt though (maybe I'm wrong). Still, I like it.

Funky Diver · Post by **Funky Diver** » Thu Jan 13, 2011 9:50 pm

The beauty of Arduino fella... just retask it if you go down the squirt route

Post by **brentp** » Thu Jan 13, 2011 9:54 pm

Eric,

I thought you had a v3 controller. So there's only one AUX channe on the V4 and it's brought out to the molex connector. The TPS and MAP share the same input internally, so you wouldn't be able to repurpose that as a 2nd AUX channel.

If you want to do some heavy duty datalogging ping us for a beta test on RaceCapture.

eric_f · Post by **eric_f** » Thu Jan 13, 2011 10:11 pm

I just checked, I have a V4 Rev C controller.

I know the TPS and MAP share the internal input. The statement you said in the other post, about having one input on the processor not used, does that apply to the V4 board? I can get it out of my enclosure one way or another but only if there is actually an unused input.

Also, on another note my MAP sensor barb broke off, suggestions on where to get a replacement.

Post by **brentp** » Thu Jan 13, 2011 10:27 pm

All of the V4 analog inputs are used. On the V3, this was put to a pad on the board; on V4, it was brought out to the molex connector.

Wow- did the barb snap off easily? the plastic on them is quite tough. You can order on from our store, or buy one from digikey or Mouser (MPX4250AP)

eric_f · Post by **eric_f** » Thu Jan 13, 2011 10:30 pm

Alright, so I'm pissing into the wind with additional inputs.

Yeah, I pulled the plastic hose line off, and I didn't notice it had snapped until now when I just looked at at.

Thanks for the part number, I'll get onto that and remove my current one and get a new one ordered up.