GPIO pull down difference with RpI 2

[meyeraxel]

Hello,

I have posted already in the Compute module forum but was asked to post here as well:

I have a circuit which switches on and off a LED connected to the GPIO25 which is connected to a transistor and a pull down resistor. Also there is a 3.3V signal coming from a PIR motion detector which is read with GPIO23. This was working all fine with a Raspberry Pi B.
Now I have changed to a Raspberry Pi B 2 where I thought the GPIO is design compatible. But my circuit is not working any more.
The GPIO25 has a voltage about 2.6V when setting it to high which is not enough to drive the transistor.
Also the input from the PIR is not recognized anymore because the voltage level is around 2.8V.

Do I have to change the pull down resistor for the Raspberry Pi 2? If yes how to change it?

[joan]

There have not been any changes in this area between the Pi B and the Pi 2.

Could you give details of the actual circuit you are using with a photo as well if possible?

[jojopi]

The GPIO25 has a voltage about 2.6V when setting it to high which is not enough to drive the transistor.

Then it is not working.

In the schematic you posted in the other thread, you do not appear to have a series resistor on the transistor base (and possibly not on the LED either). You need one, because the base-emitter junction is essentially a diode to ground, but neither the GPIO nor the transistor will be happy if you dump a lot of current through there.