User avatar
Posts: 2023
Joined: Tue Feb 07, 2012 2:14 pm
Location: Devon, UK
Contact: Website Twitter

3.6.11+ kernel: New pin state change at boot time...

Tue Feb 26, 2013 9:35 pm

I notice the I2C pins (BCM_GPIO 0 & 1) have changed state at boot time now - previously they were left as inputs and would read high due to the on-board pull-ups, but in this kernel (or somewhere in the boot sequence) they get changed from inputs to outputs and are driven low.

It's probably no big deal, but it might cause 1 or 2 projects that wasn't expecting this to have different behaviour...

Easy to notice with a ladder board plugged in - I've been used to the 2 small LEDs being lit up at boot time - now they light up for a few seconds then go off!

However it's just on Rev 1 boards - So I'm guessing it's something to do with the switching of the I2C buses over for the camera module, but all those Rev 1's out there ..... Hope no-ones relying in the pins being input and held at 3.3v at boot time for anything critical...

(Garage doors auto-opening in 3 .. 2 .. 1 .....)

Gordons projects:

Return to “General discussion”