PowerBoost and Push-button Power Switch Breakout

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sdo
 
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PowerBoost and Push-button Power Switch Breakout

Post by sdo »

I've tried your Adafruit Push-button Power Switch Breakout (ID:1400)
and liked it a lot, especially that my project (a talking multimeter)
is able to turn itself off after an idle timeout using the button's
kill pin, and later I can turn it back on with a single button
press. Very neat.

Now I'm wondering however how to get a similar effect while using one
of your PowerBoost products: that is, is it possible for the project
under load to turn itself off somehow in such a way as to disable the
booster so it doesn't keep draining the battery? I know the
PowerBoosts have an EN pin, which disconnects the whole thing when
connected to ground, I've even used it with a slide switch. But as far
as I can tell I can't easily get the latching effect that your
Push-button Power Switch Breakout has. And if I want to use a
Push-button Power Switch Breakout along with a PowerBoost, it seems as
if I'd have to place the Push-button Power Switch Breakout in between
the battery and PowerBoost: but that's inconvenient and presumably
interferes with the charging function in the PowerBoost 500
charger. Is there some trick that would give me the latching effect
using the PowerBoost's ENable pin somehow?

Thanks

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adafruit_support_mike
 
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Re: PowerBoost and Push-button Power Switch Breakout

Post by adafruit_support_mike »

The PowerBoost's EN pin doesn't have any toggling capability.

You can connect the PBPS to it like this though:

- PBPS 'In' to PowerBoost 'Bat'
- PBPS 'G' to PowerBoost 'GND'
- PBPS 'Out' to PowerBoost 'EN'

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sdo
 
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Re: PowerBoost and Push-button Power Switch Breakout

Post by sdo »

Ah of course! I knew I was missing something. Seems obvious in retrospect. Many thanks! This should be pretty convenient.

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Jereck
 
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Re: PowerBoost and Push-button Power Switch Breakout

Post by Jereck »

Hi !

I have wired a Powerboost 1000C and a PBPS as following :
- PBPS 'In' to PowerBoost 'Vs'
- PBPS 'G' to PowerBoost 'GND'
- PBPS 'Out' to PowerBoost 'EN'

And I uploaded the following test sketch (it's pretty simple) :

Code: Select all

#define PIN_SHUTDOWN 9

void setup() {
  pinMode(PIN_SHUTDOWN, OUTPUT);
}

void loop() {
  delay(5000);
  // turn off the board after 5 sec.
  digitalWrite(PIN_SHUTDOWN, HIGH);
}
It works fine as long as the battery is charged or the USB power is plugged in.

However, when the battery is low, it seems that the PBPS does not work (the board doesn't shutdown neither on the OFF signal, nor the button press).

Is it normal or is there something I didn't understand (I can't rule that out ;-) ) ?
Attachments
Powerboost +PBPS.png
Powerboost +PBPS.png (232.52 KiB) Viewed 816 times

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adafruit_support_mike
 
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Re: PowerBoost and Push-button Power Switch Breakout

Post by adafruit_support_mike »

The Push Button Power Switch uses an MC14093. The datasheet says it woks for supply voltages between 3v and 18v, but all the specifications are for 5v, 10v, and 15v.

The PowerBoost's low-battery LED comes on when the input voltage falls below about 2.9v, so that's likely to be the problem: the LiPo voltage is falling far enough that the MC14093 can't toggle properly.

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Jereck
 
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Re: PowerBoost and Push-button Power Switch Breakout

Post by Jereck »

I re-read the powerboost tutorial, and it states that "Vs = BAT". That's why I used that pin after reading your previous comment.

So, if I connect the button to the 5V pin, then it should work correctly even when the battery is low.

(I found this topic on my first Google search, I guess other newbies like me are likely to do the same mistake. Hopefully my case will help others.)

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adafruit_support_mike
 
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Re: PowerBoost and Push-button Power Switch Breakout

Post by adafruit_support_mike »

Vs is connected to the LiPo charger's load-shared output. When a USB cable is connected, it's 5v. When there's no USB power, it's the battery voltage.

In general, Vs is a good pin to choose for external circuits that need power. It just happens that the chip for the Pushbutton Power Switch cuts out at the low end of a LiPo's discharge curve.

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darkmoon3d
 
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Re: PowerBoost and Push-button Power Switch Breakout

Post by darkmoon3d »

Am able to implement same wiring solution using Push button Power switch with Powerboost 1000c and Pi Zero. Can't seem to figure out how to setup PBPS shutdown pin to a pi bcm 4. Wanting to send signal over bcm 4 (example - https://www.raspberrypi.org/forums/view ... p?t=109285) which would trigger shutdown pin.

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