ARM CM940T Motherboard detect

Programmer’s Reference

Motherboard detect

The nMBDET signal operates as follows:

nMBDET=0 The core module is attached to a motherboard, and accesses in the address range 0x0 to 0x3FFFF to the boot ROM or SSRAM are controlled by the REMAP bit.

nMBDET=1 The core module is not attached, and accesses in the address range 0x0 to 0x3FFFF are routed to the SSRAM.

Note

The SSRAM is local, which means that it can only be read by the processor on the same core module. It provides fast local memory for the local processor and cannot be accessed by other system bus masters.

4GB

Abort	Motherboard	Motherboard
CM registers	CM registers	CM registers	272MB
			256MB
SDRAM	SDRAM	SDRAM
SSRAM	Boot ROM	SSRAM	256KB
Standalone	Attached	Attached
	(after reset)	(after remap)

Figure 4-1 Effect of remap and motherboard detect

ARM DUI 0125A © Copyright ARM Limited 1999. All rights reserved. 4-3