How can I write data to variable located in flash memory?

yongjin2712_cho — Mon, 16 Jul 2018 06:57:40 GMT

I use RT1050 EVK with hyperflash

Now I'm trying to write data to variable located in flash memory.

But I can't do it

I defined rw flash section as below

MEMORY
{
/* Define each memory region */
EXT_FLASH (rx) : ORIGIN = 0x60000000, LENGTH = 0x100000 /* 1M bytes (alias Flash) */
EXT_FLASH_NVDATA (rwx) : ORIGIN = 0x60100000, LENGTH = 0x80 /* 128 bytes (alias Flash) */
EXT_FLASH_FONT (rx) : ORIGIN = 0x60100080, LENGTH = 0x80000 /* 512K bytes (alias Flash) */

...

__base_EXT_FLASH_NVDATA = 0x60100000 ;
__top_EXT_FLASH_NVDATA = 0x60100000 + 0x80 ; /* 128 bytes */

.nv_user_data : ALIGN(4)
    {
    KEEP(*(.nv_userdata))
    . = ALIGN(4);
    } > EXT_FLASH_NVDATA

And I made a code as below

uint32_t test_data __attribute__ ((section (".nv_userdata"))) __attribute__ ((aligned(4))) = 20;

void setTestData(unsigned char id)
{
test_data = 30;
} <- break point

After I set break point and run debug with MCUXpresso, I saw that value of memory is changed as below

0x60100000 : 0x60100000 <Hexadecimal>
Address 0 - 3 4 - 7 8 - B C - F
60100000 00464680 00050200 00000000 00000014 <-- before
60100010 FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF

0x60100000 : 0x60100000 <Hexadecimal>
Address 0 - 3 4 - 7 8 - B C - F
60100000 00464680 00050200 00000000 0000001E <-- after
60100010 FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF

However, After board reset, value of it's memory return to 20.

It seems to behave abnormally to acess.

And if test_data variable declares uint8_t or uint16_t, value of test_data is not changed.