Data Tranmission Method

GiODi · 07-28-2006, 01:37 PM

I have a general question: How do you determine the method of data transmission used? I've been searching for ages and now my head hurts.

evandude · 07-28-2006, 01:46 PM

data transmission method of what?

GiODi · 07-28-2006, 01:56 PM

Basically what I want to try to do is make an interface for my climate control. I know this has been covered, I've read the 1000 page post. But what I want to do is a little different. My climate control seems to be two units, one for the controls (faceplate) and one for the actual brains. I just want to remove the faceplate and use a PIC(?) to emulate the button pushes and knob turns. I believe the header for the control faceplate has a 5 pin connection. There are 6 buttons a nob and a little lcd screen.

0l33l · 08-01-2006, 12:16 AM

Quote: Originally Posted by GiODi

Basically what I want to try to do is make an interface for my climate control. I know this has been covered, I've read the 1000 page post. But what I want to do is a little different. My climate control seems to be two units, one for the controls (faceplate) and one for the actual brains. I just want to remove the faceplate and use a PIC(?) to emulate the button pushes and knob turns. I believe the header for the control faceplate has a 5 pin connection. There are 6 buttons a nob and a little lcd screen.

Using a PIC would work. That's what my AC controls are based on. I've tested it and it partly works. More info would be a trade secret

GiODi · 08-02-2006, 11:13 AM

Thanks... I think.... hahaha now I gotta look into that. If my head explodes, it's all your fault.

I got another question: I was under the impression that a button push was more or less just colosing a circuit, (like how reset buttons work on computers) I tried this with my unit and it didn't work, so I'm assuming there are other methods. Resistance maybe? Can you help me out with that? What other method are there? I've tried searching, searched so much I didn't get a thing done at work yesterday.

evandude · 08-02-2006, 11:25 AM

If your control panel has 6 buttons, a knob, and an LCD screen, and only a 5 pin header, then it may not be giving you any actual button outputs on those pins; everything could be read by an onboard microcontroller and sent via some serial protocol to the "brains". But, it could be encoding the buttons with a varying resistance type of system like steering wheel controls sometimes use, and just using serial comm for the LCD screen.

Either way, you really need to know your way around a DMM, and an oscilloscope too, if it uses serial communication... Reverse-engineering something like this is not something that anyone can just tell you how to do, you have to try a lot of different things to find out what's going on.

From the sounds of it, (especially considering there is an LCD screen on the front panel so it is most likely somewhat complex) you might be better off sending the panel to someone with more experience to try and reverse-engineer it for you.

GiODi · 08-02-2006, 11:56 AM

Sorry, It's actually 12 pins from the face plateto the control board.... I forgot to update that. Also the LCD is kind of like a digital watch, just to make sure we're clear on that as well. Sorry I've been a little unclear on what I am trying to do, it's actually two separate thing.

1) First I wasnted to remove the face plate that hold the nob and buttons, which is connected by a 12 pin header. Which is why I asked about data transmission.

2) It now seems easier to leave that control head, relocated it and emulate the button pushes on by wiring something to the buttons.

This is why I was asking about button pushes closing a circuit. If it was i could then just use a relay board and be done with it (i think). I tried really quickly last night , in the dark, and it didn't work, but now thinking back on it, I may have be trying to close the wrong pins, they may have just been posts holding the buttons in place.

shotgunefx · 08-02-2006, 11:58 AM

One thing that might be helpful would be to get the OEM service manuals off of ebay. They can reveal a lot.

GiODi · 08-02-2006, 12:03 PM

Good idea... i was actually thinking about that this morning. I wasn't sure if it would have the pin-out diagram for something like this. I called Calsonic, the maker of the unit, yesterday. They couldn't help me because technical diagrams are now owned by Nissan...

shotgunefx · 08-02-2006, 12:11 PM

Quote: Originally Posted by GiODi

Good idea... i was actually thinking about that this morning. I wasn't sure if it would have the pin-out diagram for something like this. I called Calsonic, the maker of the unit, yesterday. They couldn't help me because technical diagrams are now owned by Nissan...

I don't know about other cars, but the service manual for my car is three phonebook size volumes. It gives rough descriptions of all the signaling between ECUs and how to test them, how the column switches (and how their signaling works) and a schematic for everything in the car.

I got some more details out of supplementary stuff, like a Chrysler workbook for techs taking the electrical training class for working on my model and repairing them.

Filled in a lot of wholes.

GiODi · 08-02-2006, 04:58 PM

Thanks for the help fellas.... I just ordered the service manual. Hopefully it will tell me what I need to know, if not, I would need it later anyway.