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Ethernut 3 Memory Map

The following table shows the default memory layout for Ethernut 3 after runtime initialization.

Address Function Details
0xFFFFFFFF


0xFFC00000
On-chip Peripherals AT91R40008 Datasheet
0xFFBFFFFF











0x22100000
  Abort Exception on Access
0x220FFFFF

0x22000000
Expansion Port Memory Bus  
0x21FFFFFF


0x21100000
Reserved Abort Exception on Access
0x210FFFFF

0x21000000
CPLD Registers Ethernut 3 CPLD
0x20FFFFFF


0x20100000
Reserved Abort Exception on Access
0x200FFFFF

0x20000000
Ethernet Controller DM9000/DM9000A Datasheet
0x1FFFFFFF



0x11000000
Reserved Abort Exception on Access
0x10FFFFFF


0x10400000
Reserved Mirrored NOR Flash
0x103FFFFF


0x10000000
4 MBytes NOR Flash AT49BV322A Datasheet
0x0FFFFFFF



0x00400000
Reserved Abort Exception on Access
0x003FFFFF

0x00040000
Reserved Mirrored SRAM
0x0003FFFF
0x00000000
256 kBytes On-chip SRAM AT91R40008 Datasheet

Remapping

The memory interface has two different configurations.

  1. Reset state
  2. Normal state

The reset state is activated by switching on the power supply or by pressing the reset button. In this state the external Flash memory is located at address 0x00000000, where the CPU starts execution.

To switch from reset to normal state, the program that is running in reset state has to setup the memory configuration and issue a remap command. This is typically done by the Nut/OS startup code.

The following table shows the memory map which is configured by the BootMon boot loader.

Device Chip Select Before Remap After Remap
AT91R40008 internal RAM   0x00300000 - 0x0033FFFF 0x00000000 - 0x0003FFFF
AT49BV322A external FLASH NCS0 0x00000000 - 0x000FFFFF 0x10000000 - 0x103FFFFF
DM9000E Ethernet Controller NCS1 N/A 0x20000000 - 0x200FFFFF
CPLD Registers NCS2 N/A 0x21000000 - 0x210FFFFF
Expansion Port Memory Bus CS4 N/A 0x22000000 - 0x220FFFFF