Adafruit Touch Sensor Wiring

Discussion in 'PowerMac G4 Cube' started by velijoze, Jun 18, 2017.

  1. velijoze

    velijoze

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    Jun 18, 2017 at 6:53 PM #1
    velijoze

    velijoze

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    Mobo:
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    The build is almost complete and the only thing missing is the power switch, which I do not know how to wire.

    I’ve done some reading and ended up ordering two kinds of sensors from Adafruit, as seen in Neil’s thread, as well as small relays that he uses to send a signal to the motherboard power switch pins. However, I could not find a definitive answer on how to wire the Adafruit touch sensor and the Omron low signal relay and then connect everything back to the power switch pins on the mobo.

    Since I've already gone through one PicoPSU due to shorting, I just wanted to make sure this would be the correct procedure before I burn something else.

    Neil's thread:

    https://www.tonymacx86.com/threads/touch-sensors-three-models.155762/

    AT42QT1010 - momentary sensor
    AT42QT1012 - toggle

    [​IMG]


    Low signal relay: Omron G6A-274P-ST40-US-DC5

    http://eu.mouser.com/search/ProductDetail.aspx?r=653-G6A-274P40-DC5

    [​IMG]

    Could someone please help me with wiring this? I understand that once the touch is sensed the sensor sends the signal to the relay, which in turn sends a low signal to the power switch pins.

    Would this be correct:
    1. I’m already tapping directly into the PicoPSU to get +5V and wiring it to the VDD connector on the touch sensor
    2. I’m already taking ground directly from PicoPSU and wiring it to GND connector on the touch sensor
    3. Where should I then connect OUT from the touch sensor? I’m assuming this should go to the relay, but not sure which pin?
    4. Once the out line from the sensor is connected to the relay, which two pins should I use to send the signal back to the motherboard power switch pins?
    I’m obviously not well versed in how relays work and would really appreciate some guidance. I thank you in advance.

    Zoran
     
  2. neilhart

    neilhart Moderator

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    Jun 27, 2017 at 4:39 PM #2
    neilhart

    neilhart Moderator

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    Sorry for not seeing this query earlier.

    Anyway to wire the touch sensor and relay proceed as follows:

    This circuit works with the 5 volt standby power (noted as 5VSB) from the PSU. The 5VSB is found on pin 9 of the 24 pin ATX power connector, usually a purple wire. If you use a 24 pin extender cable to relocate the PicoPSU then there is no problem of tapping into the pin 5 purple wire. Otherwise you will need to locate the 5VSB on the motherboard as it is many times to be found on one of the header pins (check the docs).

    Wire connect the 5VSB to the VDD pin of the touch sensor.

    Wire the touch sensor GND pin to the relay pin 16 (-) and to the PSU ground black wire (choose one pin: 3,5,7,15,17,18,19 or 24).

    Wire the touch sensor OUT pin to the relay pin 1 (+).

    Wire the relay pin 13 and pin 9 to the front panel PWR SW header pins.

    As I have noted in other posts, I always wire up these circuits on the desk top using a dry cell battery pack for the +5 volts and ground just to ensure that I have identified the pins correctly and the circuit works as desired.

    Good modding,
    neil
     

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