1

I am building a WiFI solution for a DSLR camera; so after connecting you can view the image via a webbrowser. For this I gutted a so called battery 'grip', which has buttons with which normally you can take a picture, use the scroll button for ISO etc. See picture BAttery Grip

The buttons arre connected to a RPI and I use these to control the image shown in the browser via websockets, this works perfectly.

THe problem is: i want the hard on/off switch (so it is in ON OR OFF postion) to shutdown and startup the RPI.

I have a 3cell li-ion battery (15000mah) connected to a chinese buck converter with 5v in, 5v out and batt out.

So my first idead was: 5v out -> switch -> diode -> capacitor -> rpi. This does not work :-)

With this i should get a reading before the diode to GPIO pin to see if the switch is toggled, BUT the diode gives a voltage drop, so this does not work.

There are a lot of examples, but they only use momentary switches AND/OR relays, which i don;t wan't because of the current draw.

So have any one of you any idea on how to solve this?

Thanks in advance!!

Robert Alers
  • 11
  • 2
  • 1
    You can't put 5v into the gpio pin, you'll fry it. And unless the capacitor is large enough to run the pi it won't have enough time to shut down gracefully. I think what you are after is something like a power supervisor, that the RPI can tell to go to sleep when it's done shutting down. Usually this is done with an expansion board. – Ron Beyer Nov 13 '17 at 12:56
  • A pi is simply the wrong choice for this. You want something with a read-only main filesystem on a power-loss safe storage medium like an SPI flash - look for example at the Zsun wifi card readers based on the AR9331 Linux WiFi router chip. – Chris Stratton Nov 13 '17 at 15:40
  • Please use the schematic tool, it is way easier to understand than text. Please also write specific questions, you'll get better answers. – Voltage Spike Nov 14 '17 at 00:32
  • 1
    I know i can' use a 5v input, wasn't very clear on that one. I added a diagram. AR9331 is a good idea actually! Is there also a version with 15 gpio pins? – Robert Alers Nov 14 '17 at 09:25

0 Answers0