[U-Boot-Users] MC9328MXL/1 SDRAM initialization

llandre r&d2 at dave-tech.it
Fri Jan 13 10:47:24 CET 2006

I have a question about how MC9328MXL/1 initializes SDRAM memories.
These is the instructions used to set up the Mode Command Register (file 
board/mx1ads/lowlevel_init.S) for MX1ADS evalutaion board:

/* Issue Mode Register Command		*/
	ldr  r3, =0x08111800 	/* Mode Register Value 		*/
	ldr  r2, [r3]

In my understanding address lines are connected as follows:

A12 -> A13
A11 -> A12
A10 -> MA11
A9  -> MA10
A8  -> A10
A7  -> A9
A6  -> A8
A5  -> A7
A4  -> A6
A2  -> A5
A1  -> A3
A0  -> A2

Thus, when writing to address 0x08111800, microprocessor address lines 
from A8 to A6 are set to 0. It implies that SDRAM address lines from A6 
to A4 are set to 0. These lines are decoded by the SDRAM chips as CAS 
latency. Allowed values are 010 (CAS latency = 2) and 011 (CAS latency = 
3). The value 000 is reserved. So I think I'm misunderstanding how the 
SDRAM controller works. Anybody can help me?

Thanks in advance,

DAVE Electronics System House - R&D Department
web:   http://www.dave-tech.it
email: r&d2 at dave-tech.it

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