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Internal Memory

8Internal Memory

TheLM3S6965microcontrollercomeswith64KBofbit-bandedSRAMand256KBofflashmemory. The flash controller provides a user-friendly interface, making flash programming a simple task. Flash protection can be applied to the flash memory on a 2-KB block basis.

8.1Block Diagram

Figure 8-1 on page 152 illustrates the Flash functions. The dashed boxes in the figure indicate registers residing in the System Control module rather than the Flash Control module.

Figure 8-1. Flash Block Diagram

 

 

Icode

 

Flash Control

 

 

Cortex-M3

Bus

 

 

 

 

 

Dcode

 

FMA

 

 

 

 

 

 

FMD

 

 

Flash Array

 

 

Bus

 

FMC

 

 

 

 

 

 

 

 

 

 

FCRIS

 

 

 

 

 

 

 

 

 

 

 

System

Bus

 

FCIM

 

 

 

 

 

 

 

 

FCMISC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Flash Protection

 

 

Bridge

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FMPREn

 

 

 

 

 

 

 

 

FMPPEn

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Flash Timing

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

USECRL

 

 

 

 

 

 

 

 

User Registers

 

 

 

 

 

 

 

 

 

 

 

SRAM Array

 

 

 

USER_DBG

 

 

 

 

 

USER_REG0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

USER_REG1

 

 

 

8.2Functional Description

This section describes the functionality of the SRAM and Flash memories.

8.2.1SRAM Memory

TheinternalSRAMoftheStellaris® devicesislocatedataddress0x2000.0000ofthedevicememory map. To reduce the number of time consuming read-modify-write (RMW) operations, ARM has introduced bit-banding technology in the Cortex-M3 processor. With a bit-band-enabled processor, certainregionsinthememorymap(SRAMandperipheralspace)canuseaddressaliasestoaccess individual bits in a single, atomic operation.

The bit-band alias is calculated by using the formula:

bit-band alias = bit-band base + (byte offset * 32) + (bit number * 4)

For example, if bit 3 at address 0x2000.1000 is to be modified, the bit-band alias is calculated as:

0x2200.0000 + (0x1000 * 32) + (3 * 4) = 0x2202.000C

152

November 16, 2008

Preliminary

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