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Thread: G35 carputer climate controls

  1. #11
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    it looks like from the picture there are two leads going into each button and two going out. im not well versed in PCB design, but i'd wager one is for the button and one is for the LED. if you can power the LED on somehow, and take a multimeter to it to figure out which pair are for the light. then the other pair for the switch. im not sure how you'd figure out what kind of signal to send to which of the two contacts.

  2. #12
    Fusion Brain Creator 2k1Toaster's Avatar
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    Quote Originally Posted by gaoes View Post
    NO and NC are "Normally open" and "Normally Closed" respectivly. a NO contact will spend all its time as an incomplete circut, waiting for the button to be pressed or relay to be energized, at which point the contacts will close, allowing electricity to flow across the contacts enabling whatever it is its supposed to do. normally closed is exactly opposite, it will open the circut when activated.
    Correct.

    Quote Originally Posted by gaoes View Post
    im not entirely sure how you would check to see if the contact is waiting for a power or ground, but i would gather you need a multimeter.
    The safest way is to trace it. Measure resistance between each of the pins on the button and a known ground point as well as between the pins and a known vcc point. It is more than likely either:

    VCC ---/\/\/\/---|TO MCU|--- SWITCH ----|GND
    or
    VCC --- SWITCH ---|TO MCU|---/\/\/\/----|GND

    not to say it couldnt be something different, but those two above would be 95% of the designs out there.

    So depending on how much resistance between a contact and ground and a contact and power, you can tell if it is directly connected (<< 1ohm) or going through a current limit resistor (probably > 100ohms, closer to 1kohm, or 10kohm).

    Quote Originally Posted by gaoes View Post
    as for the fusion brain wiring, you'd only need one wire from the brain to the button contact to pulse either a power or ground signal (its acting like being pressed) from the brain to the contact that leads back to the circut board.

    i dont think im too far off base here, im sure 2k1toaster knows how to explain this better/correctly.
    If it is the first setup with the switched ground, then 1 wire will work, and you would break it at MCU->SWITCH and make it MCU->FB Ground of output.

    The Fusion Brain is like the first option. There is always power to the + pin. The - pin is connected and disconnected as told by the computer. So when you say "turn on" it is grounding a pin, which would ground the output, set the signal low, and trigger an event.

    Quote Originally Posted by doctr_nick View Post
    Thanks gaoes

    As an example, pushing the defrost button will turn on the defrost function and a corresponding LED on the circuit board. The LED stays on, as does the defrost function until hitting the button again. This tells me that the button must complete some sort of circuit that feeds back to a chip/switch that gives a secondary signal to keep the LED on until the button is hit again, and to keep the defrost function on.
    So in theory it would sound more like an NO to me, but I dunno.
    I'm still a little unclear with how I would go about soldering a single wire to the PCB without A) removing the switch and B) inducing some sort of short circuit given the fact that the button appears to be mounted to the PCB with four separate contact points. Any clarification would be great. Would it be as drawn here:

    Attachment 60271
    NO and NC cannot really be determined by function. For instance the code could be written for posedge signals or negedge signals. Just changing which edge triggers the code, inverts the logic.
    Fusion Brain Version 6 Released!
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  3. #13
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    Thanks so much for all the help guys! I really appreciate your patience dealing with my newb questions.

    So as it stands, if I understand correctly, 2 of the 4 contact points are likely for a connection with the LED while the other links to the MCU. So I need to first identify which 2 belong to the MCU circuit. And by the looks of it, most of that has to be done with a multimeter (which I currently do not have). Now I have the OEM board (that's similar to the pics I've posted) out of the car as I'm currently using an aftermarket controller, so the OEM one is in prime position for experimentation.

    I'll have to get my hands on my dad's multimeter... only issue is that I'm currently in medical school (which makes my schedule busy as hell), and home is 3.5+ hours away. I was really hoping someone on the forums here would have already tried something like this with a G35 to make things much simpler, but I gues not. Oh well, thanks for the guidance, and I'll post back once I make some headway.

  4. #14
    Fusion Brain Creator 2k1Toaster's Avatar
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    you can get a multimeter at rat shack for $10. Invaluable especially if you are putting in a CarPC...

    The 4 contacts on the buttons are joined. There are really only 2 contacts. 4 leads so it is stable when you push it, and it allows for traces to be routed inbetween like a bridge which I see at least one of those buttons has.
    Fusion Brain Version 6 Released!
    1.9in x 2.9in -- 47mm x 73mm
    30 Digital Outputs -- Directly drive a relay
    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
    Buy now in the MP3Car.com Store

  5. #15
    MySQL Error soundman98's Avatar
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    Quote Originally Posted by 2k1Toaster View Post
    you can get a multimeter at rat shack for $10. Invaluable especially if you are putting in a CarPC...
    if your search for harbor freight, you can get them as cheap as $3.

    Quote Originally Posted by 2k1Toaster View Post
    The 4 contacts on the buttons are joined. There are really only 2 contacts. 4 leads so it is stable when you push it, and it allows for traces to be routed inbetween like a bridge which I see at least one of those buttons has.
    exactly-- on switches that small, usually one side is one contact, but with 2 metal terminals, and on the other side, it is the other contact..

    usually switches like that are NO, but manufacturers do all sorts of weird things--NC switches could have been 0.001 cent cheaper that week of production...

  6. #16
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    Quote Originally Posted by 2k1Toaster View Post
    you can get a multimeter at rat shack for $10. Invaluable especially if you are putting in a CarPC...

    The 4 contacts on the buttons are joined. There are really only 2 contacts. 4 leads so it is stable when you push it, and it allows for traces to be routed inbetween like a bridge which I see at least one of those buttons has.
    I didn't think multimeters were that cheap. I'll have to look around this weekend.

    So essentially, if I wanted to hook up my wire, I could just add solder over top of the button such that I create a solder bridge connecting all 4 contacts and then stick the one end of the wire in the middle?

  7. #17
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    if you bridged all four contacts together, you would be essentially bypassing the (probably) NO contact, so that it is now always closed, bad juju. using the method 2k1toaster suggested, you need to figure out which two contacts always have VDC+. that is the side you do not want to solder your wire leading to your fusion brain.

    alternativly, if you cant figure it out that way, you can use a relay as your bridge (each side of the button contacts soldered to either side of the relay contacts) ground the X2 contact, and solder the X1 contact to your fusion brain. when the brain sends a momentary signal the relay contacts close, allowing electricity to flow from one side of your button to the other side via the closed relay contacts. because the relay is simulating a button you'd want to make it simply a .5 sec pulse or some such. this is a messy method because you're pretty much quadrupling your wire requirement and need a relay for every single button.

  8. #18
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    Quote Originally Posted by gaoes View Post

    alternativly, if you cant figure it out that way, you can use a relay as your bridge (each side of the button contacts soldered to either side of the relay contacts) ground the X2 contact, and solder the X1 contact to your fusion brain. when the brain sends a momentary signal the relay contacts close, allowing electricity to flow from one side of your button to the other side via the closed relay contacts. because the relay is simulating a button you'd want to make it simply a .5 sec pulse or some such. this is a messy method because you're pretty much quadrupling your wire requirement and need a relay for every single button.
    Ahhhh... Now I understand! That makes things perfectly clear. While I realize that using a relay may be more combersome in terms of wiring and such, it definitely makes the job more straightforward, which may be the better route for me given my level of knowledge with this sort of stuff. I just want something that will get the job done, and I can hide all the wiring in my dash easy enough since I essentially have to re-construct it anyway for the purposes of building it like the concept. I assume that using a relay as you outlined above no longer requires me to determine whether these switches are NO or NC, correct? ... seeing as the relay is just emulating the button and closing the circuit.

  9. #19
    Fusion Brain Creator 2k1Toaster's Avatar
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    Quote Originally Posted by doctr_nick View Post
    Ahhhh... Now I understand! That makes things perfectly clear. While I realize that using a relay may be more combersome in terms of wiring and such, it definitely makes the job more straightforward, which may be the better route for me given my level of knowledge with this sort of stuff. I just want something that will get the job done, and I can hide all the wiring in my dash easy enough since I essentially have to re-construct it anyway for the purposes of building it like the concept. I assume that using a relay as you outlined above no longer requires me to determine whether these switches are NO or NC, correct? ... seeing as the relay is just emulating the button and closing the circuit.
    Correct. The relay just completes the circuit, it doesnt care what it is completing.
    Fusion Brain Version 6 Released!
    1.9in x 2.9in -- 47mm x 73mm
    30 Digital Outputs -- Directly drive a relay
    15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
    Buy now in the MP3Car.com Store

  10. #20
    MySQL Error soundman98's Avatar
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    well, you do need to determine if the switches are NO, or NC. if they are NC, connecting a relay along-side the switch will not work--because you would need to break the connection for the system to recognize the button press..

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