ARM CM940T Local address, System bus address, System bus accesses to SDRAM

Programmer’s Reference

System bus accesses to SDRAM

If the core module is mounted on a motherboard, the SDRAM is mapped to appear at the aliased module memory region of the combined Integrator system bus memory map. The SDRAM can be accessed by all bus masters at its alias location, and accessed by the local processor at both its local and alias locations.

The system bus address for a core module is automatically controlled by its position in the stack (see Core module ID on page 2-6). Figure 4-3shows the local and alias address of the SDRAM on four core modules.

System bus address		Local address
0xBFFFFFFF		0x0FFFFFFF
0xBFFFFFFF	SDRAM	0x0FFFFFFF
	SDRAM	Module 3
	core module 3	Module 3
	core module 3
0xB0000000		0x00000000
0xAFFFFFFF		0x0FFFFFFF
0xAFFFFFFF	SDRAM	0x0FFFFFFF
	SDRAM	Module 2
	core module 2	Module 2
	core module 2
0xA0000000		0x00000000
All masters
0x9FFFFFFF		0x0FFFFFFF
0x9FFFFFFF	SDRAM	0x0FFFFFFF
	SDRAM	Module 1
	core module 1	Module 1
	core module 1
0x90000000		0x00000000
0x8FFFFFFF		0x0FFFFFFF
0x8FFFFFFF	SDRAM	0x0FFFFFFF
	SDRAM	Module 0
	core module 0	Module 0
	core module 0
0x80000000		0x00000000

Figure 4-3 Core module local and alias addresses

By reading the CM_STAT register, a processor can determine which core module it is on and, therefore, the alias location of its own SDRAM (see CM_STAT (0x10000010) on page 4-12).

ARM DUI 0125A

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