The C example “Flashing an LED using the Raspberry PI and C Programming Language” by Gert van Loo & Dom Flashing an LED don't works on the Raspberry Pi B2. For that one small midifikation has been done, change:

#define BCM2708_PERI_BASE        0x20000000
#define GPIO_BASE                (BCM2708_PERI_BASE + 0x200000) /* GPIO controller */

into:

#define BCM2736_PERI_BASE        0x3F000000
#define GPIO_BASE                (BCM2736_PERI_BASE + 0x200000) /* GPIO controller */

Code:
http://dernulleffekt.de/download/blink_GPIO18_BCM2835-36.c

The Raspberry Pi B has the SoC BM2835 and the Raspberry Pi B2 has the Soc BM2836 on the Board. That means working with the GPIOs needs different code.

GPIO Hardware
http://elinux.org/Rpi_Low-level_peripherals

Raspberry Pi GPIO Manual for Wiring, C and C++
http://raspberrypiguide.de/howtos/raspberry-pi-gpio-how-to/
https://learn.sparkfun.com/tutorials/raspberry-gpio
http://www.pieter-jan.com/node/15

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