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.

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.

https://forum.allaboutcircuits.com/threads/half-bridge-circuit-with-dual-supply.53364/

googled that for you

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