EmbDev.net

Forum: µC & Digital Electronics Reverse polarity via GPIO


Author: Tim (Guest)
Posted on:
Attached files:

Rate this post
0 useful
not useful
Hi,

I have a Raspberry Pi camera with switchable IR filter, I want to 
control this filter with the GPIOs of the Raspberry Pi. I used an 
oscilloscope (see my images) to measure the switching signal (by default 
the filter is switched by the led of camera). To make the filter switch 
in one direction I need to apply 3,3V for about 150ms (no problem so 
far) but to switch it back (to make the filter go away) I need to apply 
the 3,3V with reversed polarity.

What (easy and cheap) circuit can I use to give a signal in both 
directions?
(So one GPIO in one direction and another for the other direction.

Author: Bomwollen (Guest)
Posted on:

Rate this post
0 useful
not useful
I think you should control a half bridge with two gpios.
Generate the -3v3 with a single inverting charge pump. You don't tell 
about current needs. There are many cheap charge pump ICs like icl7660 
available.

Author: Bomwollen (Guest)
Posted on:

Rate this post
0 useful
not useful

Author: Tim (Guest)
Posted on:

Rate this post
0 useful
not useful
Thank you very much, that looks very promising. Current draw should be 
minimal as it uses a power rail thought for a SMD LED, I haven't 
measured it though

Reply

Entering an e-mail address is optional. If you want to receive reply notifications by e-mail, please log in.

Rules — please read before posting

  • Post long source code as attachment, not in the text
  • Posting advertisements is forbidden.

Formatting options

  • [c]C code[/c]
  • [avrasm]AVR assembler code[/avrasm]
  • [code]code in other languages, ASCII drawings[/code]
  • [math]formula (LaTeX syntax)[/math]




Bild automatisch verkleinern, falls nötig