NAME

       avr_io - <avr/io.h>: AVR device-specific IO definitions

SYNOPSIS

   Macros
       #define _PROTECTED_WRITE(reg,  value)
       #define _PROTECTED_WRITE_SPM(reg,  value)

Detailed Description

       #include <avr/io.h>

       This header file includes the apropriate IO definitions for the device that has been specified by the
       -mmcu= compiler command-line switch. This is done by diverting to the appropriate file <avr/ioXXXX.h>
       which should never be included directly. Some register names common to all AVR devices are defined
       directly within <avr/common.h>, which is included in <avr/io.h>, but most of the details come from the
       respective include file.

       Note that this file always includes the following files:

       #include <avr/sfr_defs.h>
       #include <avr/portpins.h>
       #include <avr/common.h>
       #include <avr/version.h>

        See <avr/sfr_defs.h>: Special function registers for more details about that header file.

       Included are definitions of the IO register set and their respective bit values as specified in the Atmel
       documentation. Note that inconsistencies in naming conventions, so even identical functions sometimes get
       different names on different devices.

       Also included are the specific names useable for interrupt function definitions as documented here.

       Finally, the following macros are defined:

       • RAMEND
          The last on-chip RAM address.

       • XRAMEND
          The last possible RAM location that is addressable. This is equal to RAMEND for devices that do not
         allow for external RAM. For devices that allow external RAM, this will be larger than RAMEND.

       • E2END
          The last EEPROM address.

       • FLASHEND
          The last byte address in the Flash program space.

       • SPM_PAGESIZE
          For devices with bootloader support, the flash pagesize (in bytes) to be used for the SPM instruction.

       • E2PAGESIZE
          The size of the EEPROM page.

Macro Definition Documentation

   #define _PROTECTED_WRITE(reg, value)
       Write value value to IO register reg that is protected through the Xmega configuration change protection
       (CCP) mechanism. This implements the timed sequence that is required for CCP.

       Example to modify the CPU clock:

       #include <avr/io.h>

       _PROTECTED_WRITE(CLK_PSCTRL, CLK_PSADIV0_bm);
       _PROTECTED_WRITE(CLK_CTRL, CLK_SCLKSEL0_bm);

   #define _PROTECTED_WRITE_SPM(reg, value)
       Write value value to register reg that is protected through the Xmega configuration change protection
       (CCP) key for self programming (SPM). This implements the timed sequence that is required for CCP.

       Example to modify the CPU clock:

       #include <avr/io.h>

       _PROTECTED_WRITE_SPM(NVMCTRL_CTRLA, NVMCTRL_CMD_PAGEERASEWRITE_gc);

Author

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