MSP430F249: MSP430F249

sasi kumar1

Part Number: MSP430F249

how to retain the change in variable value after switching off the microcontroller in flash memory, I tried to declare it globally but no use any other options available

over 4 years ago

0 Eason Zhou over 4 years ago

TI__Mastermind 35760 points

Hi,

The global variable is saved in RAM and not in flash. When it power on, it will initialize the variable.

If you want to save the value, you need to write to flash memory at last.

Eason

0 sasi kumar1 over 4 years ago in reply to Eason Zhou

Expert 1090 points

Hi,

From the MSP430userguide i found a sample program for writing in flash memory which is in assembler language

MOV #WDTPW+WDTHOLD,&WDTCTL ; Disable WDT
L1 BIT #BUSY,&FCTL3 ; Test BUSY
JNZ L1 ; Loop while busy
MOV #FWKEY+FSSEL1+FN0,&FCTL2 ; SMCLK/2
MOV #FWKEY,&FCTL3 ; Clear LOCK
MOV #FWKEY+WRT,&FCTL1 ; Enable write
MOV #0123h,&0FF1Eh ; 0123h -> 0FF1Eh
L2 BIT #BUSY,&FCTL3 ; Test BUSY
JNZ L2 ; Loop while busy
MOV #FWKEY,&FCTL1 ; Clear WRT
MOV #FWKEY+LOCK,&FCTL3 ; Set LOCK
... ; Re-enable WDT?

Is there a sample program in C language, or how to declare the address in c

0 Bruce McKenney47378 over 4 years ago in reply to sasi kumar1

Guru 91390 points

Example msp430x24x_flashwrite_01.c demonstrates writing flash. It works with 64 bytes, but you can change that.

http://dev.ti.com/tirex/explore/node?node=ACj45ei3w0K2qJIgvgGzgw__IOGqZri__LATEST

Be a little careful with this example. It writes the same flash location(s) repeatedly without pause. So don't let it just run, rather stop it after one pass using a breakpoint. It will wear out the flash in (as I recall) about a half-hour.

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MSP430F249: MSP430F249