[Help] Read/Write Variable in Flash Memory

Have you tried the search feature in this forum?

http://e2e.ti.com/search/default.aspx#q=MSP430G2553+saving+data+in+FLASH&qn=&qe=&qa=&t=&g=93&author=&sc=forum&as=0&c=false&pageSize=15&sort=&defaultAskForumId=0&pi1680537405=1&category=forum&categoryVisible=6&group=93&groupVisible=3

I;m so sory
I was read a lot of them, but my problem still don't solved
please tell me how to read and write to segment A,B,C or D.
I need to store only a variable.

Le Thanh Trieu said:

please tell me how to read and write to segment A,B,C or D.

And about reading, well flash is just read-only memory. you read it as you would read form any ram location too. This is basic C knowledge (keyword: data pointers)

Only if you want to write to flash and turn it from read-only memory into difficult-and slow-to-write memory, you need specific code. Which is discussed in all these threads.

Thanks for your answer!!

I was read sample code of TI.And fix it for me, please see below code:

[code]

#ifndef FLASH_H_
#define FLASH_H_

#include "msp430g2452.h"

#ifndef TIMER0_A1_VECTOR
#define TIMER0_A1_VECTOR TIMERA1_VECTOR
#define TIMER0_A0_VECTOR TIMERA0_VECTOR
#endif

void flash_write_segmentC (unsigned char value, unsigned char position)
{
char *Flash_ptr; // Flash pointer

Flash_ptr = (char *) 0x1040; // Initialize Flash pointer
Flash_ptr += position; // Jump to desired address
FCTL1 = FWKEY + ERASE; // Set Erase bit
FCTL3 = FWKEY; // Clear Lock bit
*Flash_ptr = 0; // Dummy write to erase Flash segment

FCTL1 = FWKEY + WRT; // Set WRT bit for write operation

*Flash_ptr = value; // Write value to flash

FCTL1 = FWKEY; // Clear WRT bit
FCTL3 = FWKEY + LOCK; // Set LOCK bit
}
void flash_read_segmentC (unsigned char *var, unsigned char position)
{
char *Flash_ptr; // Segment C pointer

Flash_ptr = (char *) 0x1040; // Initialize Flash segment C pointer
Flash_ptr += position; // Jump to desired address

*var = *Flash_ptr; // copy value segment C to variable

}
void flash_write_segmentD (unsigned char value, unsigned char position)
{
char *Flash_ptr; // Flash pointer

Flash_ptr = (char *) 0x1000; // Initialize Flash pointer
Flash_ptr += position; // Jump to desired address
FCTL1 = FWKEY + ERASE; // Set Erase bit
FCTL3 = FWKEY; // Clear Lock bit
*Flash_ptr = 0; // Dummy write to erase Flash segment

FCTL1 = FWKEY + WRT; // Set WRT bit for write operation

*Flash_ptr = value; // Write value to flash

FCTL1 = FWKEY; // Clear WRT bit
FCTL3 = FWKEY + LOCK; // Set LOCK bit
}
void flash_read_segmentD (unsigned char *var, unsigned char position)
{
char *Flash_ptr; // Segment C pointer

Flash_ptr = (char *) 0x1000; // Initialize Flash segment C pointer
Flash_ptr += position; // Jump to desired address

*var = *Flash_ptr; // copy value segment C to variable

}

/////////////////////////////////////////////////////////////////////////////

#endif /* FLASH_H_ */

void write_alarm_2_flash (void)
{
flash_write_segmentC (min_alarm, 0);
flash_write_segmentD (hour_alarm, 0);
}
void read_alarm_from_flash (void)
{
flash_read_segmentC (&min_alarm, 0);
flash_read_segmentD (&hour_alarm, 0);
if (hour_alarm == 0xFF) hour_alarm = 0x06;
if (min_alarm == 0xFF) min_alarm = 0x00;
}

[/code]

please tell me about code? it is correct??? In this code, I want to set a time to alarm clock. 

I had a similar question, so I searched the forum and found this.  Not surprised.  Every time I search the forum I find nothing but posts like this where the "experts" just yell at the OP to search the forums and then never answer the poor guy.  I think the only question that you can get the answer to by searching the forums is "hey should I search the forums instead of posting my question?"  Guess I'll just figure it out my own, right after I look up the definition of "recursion."

CHRISTOPHER HUNT said:

Every time I search the forum I find nothing but posts like this where the "experts" just yell at the OP to search the forums

Then I would argue that you are not very skilled in searching. If you search the forum for Variable and Flash:

http://e2e.ti.com/search/default.aspx#q=variable+flash&g=93&sc=forum

The second result has a lot of information in it. http://e2e.ti.com/support/microcontrollers/msp430/f/166/t/224545.aspx

The third result also has good information: http://e2e.ti.com/support/microcontrollers/msp430/f/166/p/18782/630061.aspx#630061

Do you have a specific question on something you can't get to work?

Perhaps I exaggerated when I said I find "nothing but posts like this."  I did find some helpful ones as well.  What I should have said was that it's rather discouraging when the first several posts I find are ones in which long-time members of the "community" snidely berate newcomers for their lack of skills.  Wading through them to get to useful information breeds frustration.  Your links are also quite useful, though, so thank you for that.

This only shows how many people are starting a new thread for already answered questions instead of using the forum search first. I agree that it is frustrating to search through a heap of ‘empty’ threads. However, imagine how frustrating it is to have the same question asked again and again – and having to write the same answer again and again. Not to mention the time wasted for repetitions instead of solving problems where there are not dozens of answers already available. Of course I could search my old answers and copy them, but why should I waste my time in using the forum search to answer a thread of someone who could have used the search as well?