MSP430FG6626: Using the FLASH2 region as writable memory

You cannot use flash memory as though it were RAM. Writing requires specific setup and possibly an erase cycle as well. This can of course be done by your application but not with named variables and such that C understands. Assuming you compile in small mode so that there is no chance that the compiler/liniker will put anything into that upper block of flash, you can deal with it any way you like.

Is there an example of how to do this in the application? I knew about needing to erase the data before doing a write, but I was wondering if it is a matter of ptr = flashaddr; *ptr = 0; *ptr = val; or something like that, or do you need something more elaborate?

The documentation is pretty clear on the process but if you need an example, TI provides a package of code examples for most parts. Linked from the product page. Try there.

I saw the example of a flash write in the msp430ware library and it does it for the INFO segments, would this apply to the code/memory segments (FLASH2)?

Main: code memory

Bank 3 32KB 0243FFh to 01C400h

Bank 2 32KB 01C3FFh to 014400h 

Bank 1 32KB 0143FFh to 00C400h 3

Bank 0 32KB 00C3FFh to 004400h 

Flash_ptrC = (char *) 0x1880; // Initialize Flash segment C ptr
Flash_ptrD = (char *) 0x1800; // Initialize Flash segment D ptr

__disable_interrupt(); // 5xx Workaround: Disable global
// interrupt while erasing. Re-Enable
// GIE if needed
FCTL3 = FWKEY; // Clear Lock bit
FCTL1 = FWKEY|ERASE; // Set Erase bit
*Flash_ptrD = 0; // Dummy write to erase Flash seg D
FCTL1 = FWKEY|WRT; // Set WRT bit for write operation

for (i = 0; i < 128; i++)
{
*Flash_ptrD++ = *Flash_ptrC++; // copy value segment C to seg D
}

FCTL1 = FWKEY; // Clear WRT bit
FCTL3 = FWKEY|LOCK; // Set LOCK bit

Will this work if I change say Flash_ptrC to the location of FLASH2?

Flash_ptrC = (char*)0x243FF (bank 3);

You can try this code and modify the flash pointer to FLASH2 area.

dev.ti.com/.../node