Note that the schematic for the Raspberry Pi 3 Model B has not been released so we are unable to confirm if there are any changes to the specific signals used on the display and camera connectors.

Changes Compared to Raspberry Pi 1

The Raspberry Pi 2 uses a new processor model so some pin additional functions may have changed.

The same GPIO pins are used for the Raspberry Pi 3 (e.g. GPIO2, GPIO3, etc).

The GND, +5V, +3V3, UART, I2C and SPI bus pins are in the same places.

The PWM specific pin is no longer marked as PWM and now 7 pins are marked as 'GPIO GEN0' to 'GPIO GEN6'.

IO Pins

All IO pins are 3.3V, not 1.8V.  Pins are not 5V tolerant.

Full details are available here

Power-up State

Its likely all pins are set as inputs on power up (TBC).

I2C pins (e.g. Pj-3 and P8-5) are therefore high due to the pull up resistors on these pins.


Pull up resistors are included on the RPi board so are not needed externally (true for RPi1 Model B so presumably true for RPi 2 Model B, but not confirmed as full schematic not yet available).

Interfacing the RPi 3.3V I2C pins to a 5V device like an Arduino – see here.


The Chip Select signals are for up to two independent slave devices.  It seems that with the SPI port enabled in Raspbian both the CS0 and CS1 pins are assigned to it and therefore can't be used as IO (our assumption – correct?)

3.3V / 5V Interfacing

See our other page here

ID_SD & ID_SC Pins

These are for an auto configuration eeprom which you can include on your RPi add on board and which Raspbian will read to detect the board connected.  For more info see here.




We benefit hugely from resources on the web so we decided we should try and give back some of our knowledge and resources to the community by opening up many of our company’s internal notes and libraries through mini sites like this. We hope you find the site helpful.
Please feel free to comment if you can add help to this page or point out issues and solutions you have found, but please note that we do not provide support on this site. If you need help with a problem please use one of the many online forums.


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