Hello, guys!
I have a quick question about FSMC's ECC routine.
From what I understood, the workflow goes like this:
1) Enable ECC computation
SET_BIT(hnand->Instance->PCR, FMC_PCR_ECCEN);
2) Write data to the target device
3) Get the computed ECC
while (__FMC_NAND_GET_FLAG(hnand->Instance, hnand->Init.NandBank, FMC_FLAG_FEMPT) == RESET) ;
uint32_t ecc = hnand->Instance->ECCR;
3) Disable ECC
CLEAR_BIT(hnand->Instance->PCR, FMC_PCR_ECCEN);
Rinse and repeat.
It works as expected, but with a small caveat: my NAND page size is 8kb + 448 bytes.
And, as per the FSMC's docs, it can generate an error correction code of up to 32 bits. These are clearly insufficient to provide more than error detection. Because of the huge page size, getting a 0-bit or 1-bit error is highly unlikely.
Because speed is somewhat of an issue, I can't really rely on software ECC computation, so I'm trying to "trick" the FMC peripheral into providing separate ECC bits for chunks of the written page, like so:
uint16_t eccCounter = 0;
for (index = 0U; index < PAGE_SIZE; index++) // PAGE SIZE IS 8 * 1024
{
// START THE ECC COMPUTATION
if(eccCounter == 0)
{
SET_BIT(hnand->Instance->PCR, FMC_PCR_ECCEN);
}
// WRITE THE NEXT BYTE TO DEVICE
*(__IO uint8_t *)deviceaddress = *buff;
buff++;
__DSB();
if(eccCounter++ == 0xFF)
{
// WAIT FOR ECC READY
while (__FMC_NAND_GET_FLAG(hnand->Instance, hnand->Init.NandBank, FMC_FLAG_FEMPT) == RESET) ;
// GET GENERATED ECC
uint32_t ecc = hnand->Instance->ECCR;
debug_print("%08X | ", ecc);
// STOP ECC COMPUTATION
CLEAR_BIT(hnand->Instance->PCR, FMC_PCR_ECCEN);
eccCounter = 0;
}
}
debug_print("\n");
So basically I'm trying to get the ECC for different chunks of the same page, whilst sending them to the device.
The FMC device ECC Page Size is set to 256 byte.
However, after the first ECC Computation, which yields a value, all subsequent values are 0.
Any kind of help would be greatly appreciated! Thank you!
