Trouble Using Switch as Power Button for Feather

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aidanjwhelan
 
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Joined: Sun Oct 02, 2022 9:43 pm

Trouble Using Switch as Power Button for Feather

Post by aidanjwhelan »

Hi all,

I'm working on a project that uses a Feather nRF52 to control a ring of NeoPixel LEDs, and I'd like to use a tactile momentary switch as a power button, like this page shows. I've purchased an Adafruit Push-button Power Switch Breakout that uses a Pass FET to make a tactile momentary switch behave like a latching switch, which I've wired as shown in the Fritzing diagram below.

My problem is: when the Feather is powered on by connecting the battery (or any other source), the button shows no behavior or change to the Feather. The Feather is always on, and the button may as well not be there.

Am I using this button breakout correctly?
Fritzing diagram of Feather, LED ring, and Button breakout.
Fritzing diagram of Feather, LED ring, and Button breakout.
FeatherPowerSwitch.jpg (891.76 KiB) Viewed 52 times

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dastels
 
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Re: Trouble Using Switch as Power Button for Feather

Post by dastels »

I see a definite problem, and a potential/likely one.

First, you're not powering the switch board. To quote the product description:
connect the power source to Ground and IN
That leads to the second problem. You're not using the switch board for what it's intended to be used for. It's for switching power to a circuit, not connecting a pin to ground. The In pin provides power for both the board,itself, as well as the circuit that is being controlled (via that Out pin). It's not a replacement for an SPST switch, it's a power controller.

Now, that said, what you want for your purpose *is* on that board: the output of the flipflop that controls the FET. I found and rendered the schematic, which is attached. I'm thinking that you want to use the GATE signal (pin 11 of the NAND chip) or the point between the two gates (pin 10 of the chip). Which you want depends on which comes up the default state you want (Feather on or off). The attached notated photo of the bottom of the board shows the two points to solder a wire to. The right hand point is pin 11.

Dave
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