Hi,
I'm having problems writing to the internal flash of a SAME54P20A MCU on a SAME54 Xplained Pro board. I'm seeing flash corruption and getting errors with the debugger stopping to respond.
The problem was discovered in a bigger code base, but I've managed to reproduce it with using a small Atmel Start based example. Using the LED flasher example and adding a Flash driver component to the project, I've modified the FLASH_0_example() function like so:
static uint8_t chk_data[512];
/**
* Example of using FLASH_0 to read and write Flash main array.
*/
void FLASH_0_example(void)
{
uint8_t a1[16] = {0x1a, 0x27, 0x00, 0x00, 0x00, 0x0f, 0x04, 0x00, 0xff, 0xff, 0xad, 0xfd, 0x00, 0x00, 0x00, 0x00};
uint8_t a2[4] = {0xa5, 0x5a, 0xaa, 0x55};
uint8_t b1[28] = {0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x3f, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x34, 0x00, 0x0a, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
uint8_t b2[4] = {0xa5, 0x5a, 0xaa, 0x55};
flash_append(&FLASH_0, 0x80024, a1, sizeof(a1));
flash_read(&FLASH_0, 0x80024, &chk_data[0x24], sizeof(a1));
flash_append(&FLASH_0, 0x80020, a2, sizeof(a2));
flash_read(&FLASH_0, 0x80020, &chk_data[0x20], sizeof(a2));
flash_append(&FLASH_0, 0x80004, b1, sizeof(b1));
flash_read(&FLASH_0, 0x80004, &chk_data[0x04], sizeof(b1));
flash_append(&FLASH_0, 0x80000, b2, sizeof(b2)); // <-- This write is corrupted
flash_read(&FLASH_0, 0x80000, &chk_data[0x00], sizeof(b2)); // <-- Debugger stops working after this line
}
And the main() function:
int main(void)
{
atmel_start_init();
FLASH_0_example();
while (true) {
delay_ms(500);
gpio_toggle_pin_level(LED0);
}
}
As you can see I'm doing partial writes to the flash. The error that occurs is
that the last write is corrupted:
0x00080000 a5 5a aa 15 01 00 00 00 00 00 80 3f 00 00 00 00 ¥Zª.......€?.... // <-- The first bytes should be a5 5a aa 55
0x00080010 00 00 00 00 01 00 34 00 0a ff ff ff ff ff ff ff ......4..ÿÿÿÿÿÿÿ
0x00080020 a5 5a aa 55 1a 27 00 00 00 0f 04 00 ff ff ad fd ¥ZªU.'......ÿÿ.ý
0x00080030 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff ....ÿÿÿÿÿÿÿÿÿÿÿÿ
Another problem that occurs is that the debugger stops working after the last read and stops responding. The LED also does not blink, so the loop is not entered. If I run the project without a debugger the LED blinks, so the MCU does not lock up in that case. But reading back the flash memory using the debugger, I can see that the same flash corruption occurs.
I've tried disabling the cache lines in the NVM controller, but it does not help. Does anyone know why this is happening? Does the SAME54 not support multiple partial writes to it's internal flash pages? I can't find anything in the data sheet about any limitations.
