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I am interested to know how we can find out at which address are my hardware registers mapped on "/dev/mem".

Suppose if someone am interested to control GPIO using mmap command.

http://elinux.org/RPi_Low-level_peripherals#GPIO_Driving_Example_.28C.29

This link tell the mapping directly, but does not tell how can we find at what address does mapping for hardware devices starts ?

Please suggest on this point.

Any reply will be appreciable.

Regards.

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  • Have you looked into this question?
    – Sai
    Commented Nov 24, 2012 at 15:31
  • Here is another interesting question about it.
    – Jivings
    Commented Nov 25, 2012 at 8:29

1 Answer 1

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The code you reference is using the following to address the GPIO controller.

// Access from ARM Running Linux

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

The GPIO base address is 0x20200000

The code maps this address to an allocated piece of RAM (i.e. a buffer).

1
  • but data sheet says ;--
    – apple
    Commented Nov 25, 2012 at 6:48

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