Forum

Improved on/off board  

  RSS

geoff
(@geoff)
New Member
Joined:4 months  ago
Posts: 3
August 31, 2017 2:51 am  

Hello,

I have an improved on/off board and and have it hook up to a raspberry pi 3 and everything seems to work okay the first time.  I connect switch to -in and the pi powers up I connect switch to -in again and the pi powers down gracefully but when I connect switch to -in again it powers on for about 2 seconds and then the pi powers off.  If I fully remove power from the on/off board it will work again.

I did notice that about 2.3V remains on the out+ and out- pins.

Any ideas what I could be doing wrong.

FYI, I am using gpio pins 23 and 24 and have dtoverlay=gpio-poweroff,gpiopin=24,active_low="y" in my config.txt and the python script has been modified to use pin 23.

Thanks,

Geoff


ReplyQuote
geoff
(@geoff)
New Member
Joined:4 months  ago
Posts: 3
August 31, 2017 3:04 am  

Okay, so a little more troubleshooting.  It seems like the 2.3V is backfeeding from the HDMI port... If I remove the HDMI connection the on/off board works perfectly every time.

Edited: 4 months  ago

ReplyQuote
geoff
(@geoff)
New Member
Joined:4 months  ago
Posts: 3
August 31, 2017 3:47 am  

okay so after a little more investigation it seems that the when you connect the improved on/off board to the gpio pins to power the pi (pins 4 and 6 in my case) it receives a ~2V backfeed from the HDMI port (at least on the 3 monitors I tested it on) thus causing some issues with the on/off board not fully being able to eliminate power to the pi.  If I power the pi over the usb header everything seems to function okay as long as I wait for the board to get below 0.6V before powering it back on.

Edited: 3 months  ago

ReplyQuote
othermod
(@othermod)
Reputable Member Admin
Joined:1 year  ago
Posts: 271
August 31, 2017 9:59 am  

I'm not sure what to make of the HDMI issue. The USB connector is routing power to the same parts of the board as those pins.

There's going to be a small delay before you can turn everything back on, and it's related to how long it takes for a GPIO to pull high at bootup. If you use GPIO14 you can probably reduce that delay substantially.


ReplyQuote
Andrew Smith
(@drewes)
New Member Customer
Joined:5 months  ago
Posts: 2
September 6, 2017 1:22 am  

I ordered 2 of these boards and only one worked. I had the same issue you are having, and it just turned out to be a defective board


ReplyQuote
othermod
(@othermod)
Reputable Member Admin
Joined:1 year  ago
Posts: 271
September 6, 2017 1:35 am  

Issues with the on/off board, or with the RPi?


ReplyQuote
Andrew Smith
(@drewes)
New Member Customer
Joined:5 months  ago
Posts: 2
September 7, 2017 2:12 am  

on/off board


ReplyQuote
othermod
(@othermod)
Reputable Member Admin
Joined:1 year  ago
Posts: 271
September 7, 2017 4:04 pm  

I'd like to get more info about what exactly the board was doing. If the HDMI is backfeeding power and keeping the GPIO pins pulled high, then the board will stay on. This is the first time I've heard of this occurring, but it's certainly possible.

You say that one was defective and having the same problem, and that the other works. If they are operating differently I would very much like to figure out why. If I send you a label, will you send the defective one to me so I can test it?


ReplyQuote
woozer
(@woozer)
Active Member
Joined:11 months  ago
Posts: 6
September 19, 2017 8:33 pm  

Hi, what would be the minimal input voltage, would the board work with a lipo cell as power input in stead of 5v USB.

Thanks!


ReplyQuote
othermod
(@othermod)
Reputable Member Admin
Joined:1 year  ago
Posts: 271
September 19, 2017 9:48 pm  

Yes, it is designed to work down to about 2.5v. 


woozer liked
ReplyQuote
  
Working

Please Login or Register