LM3S601 Datasheet, PDF (116/446 Pages) List of Unclassifed Manufacturers – Microcontroller

Internal Memory
7.3
7.3.1
■ Loading the debug disable sequence into SRAM and running it once from SRAM after
programming the final end application code into flash
Flash Memory Initialization and Configuration
This section shows examples for using the flash controller to perform various operations on the
contents of the flash memory.
Changing Flash Protection Bits
As discussed in “Flash Memory Protection” on page 114, changes to the protection bits must be
committed before they take effect. The sequence below is used change and commit a block protection
bit in the FMPRE or FMPPE registers. The sequence to change and commit a bit in software is as
follows:
1. The Flash Memory Protection Read Enable (FMPRE) and Flash Memory Protection Program
Enable (FMPPE) registers are written, changing the intended bit(s). The action of these changes
can be tested by software while in this state.
2. The Flash Memory Address (FMA) register (see page 119) bit 0 is set to 1 if the FMPPE register
is to be committed; otherwise, a 0 commits the FMPRE register.
3. The Flash Memory Control (FMC) register (see page 121) is written with the COMT bit set. This
initiates a write sequence and commits the changes.
There is a special sequence to change and commit the DBG bits in the Flash Memory Protection
Read Enable (FMPRE) register. This sequence also sets and commits any changes from 1 to 0 in
the block protection bits (for execute-only) in the FMPRE register.
1. The Flash Memory Protection Read Enable (FMPRE) register is written, changing the intended
bit(s). The action of these changes can be tested by software while in this state.
2. The Flash Memory Address (FMA) register (see ppage 119) is written with a value of 0x900.
3. The Flash Memory Control (FMC) register (see page 121) is written with the COMT bit set. This
initiates a write sequence and commits the changes.
Below is an example code sequence to permanently disable the JTAG and SWD interface to the
debug module using Luminary Micro's DriverLib peripheral driver library:
#include "hw_types.h"
#include "hw_flash.h"
void
permanently_disable_jtag_swd(void)
{
//
// Clear the DBG field of the FMPRE register. Note that the value
// used in this instance does not affect the state of the BlockN
// bits, but were the value different, all bits in the FMPRE are
// affected by this function!
//
HWREG(FLASH_FMPRE) &= 0x3fffffff;
//
// The following sequence activates the one-time
116
October 01, 2007
Preliminary