topic Re: S08DZ EEPROM Sector Erase Problem in 8-bit Microcontrollers

S08DZ EEPROM Sector Erase Problem

datamstr — Fri, 07 Jan 2011 07:48:47 GMT

Hi All,

I can write a byte to the EEPROM on the S08DZ32, but can't erase a sector. I am using the same C code that i use for programming a byte, but just changing the command byte from 0x20 to 0x40. Will someone post their EEPROM erase code so I can compare?

Thanks,
David

Re: S08DZ EEPROM Sector Erase Problem

bigmac — Tue, 11 Jan 2011 09:48:11 GMT

Hello David,

Unless you take suitable precautions, it may be possible for COP reset to occur before the sector erase process completes. Does a reset actually occur when you attempt to erase? Programming a single byte is a much quicker process.

Within the EEPROM or RAM based code loop, that waits until the programming/erase process is complete, it is advisable to reset the COP timer, each time through the loop.

Regards,

Mac

Re: S08DZ EEPROM Sector Erase Problem

datamstr — Tue, 18 Jan 2011 22:23:41 GMT

Hi Mac,

Thanks for your feedback! I did not enable the COP using the Device Initializer and was not planning to enable the COP.

It looks like the COP is enabled by default, though. I will do some more testing.

Thanks,
David

Re: S08DZ EEPROM Sector Erase Problem

Lundin — Tue, 18 Jan 2011 22:53:26 GMT

I just finished writing a new eeprom driver for the S08DZ this very day, so I'm very much up-to-date on all bits and bytes. If you post your code, I'll be happy to take a look at it.

Re: S08DZ EEPROM Sector Erase Problem

datamstr — Wed, 19 Jan 2011 00:07:18 GMT

Hello Lundin,

Here is my code, I found it on this forum.

Write a byte works OK, so I simply changed the FCMD to ERASE_SECTOR.

Thanks,
David

#define EEPROM_BASE 0x1600 // Base address for EEPROM memory in a DZ32
#define EEPROM_ACCESS(x) *(unsigned char *)(x + EEPROM_BASE)
#define BYTE_PROGRAM 0x20
#define ERASE_SECTOR 0x40

// Code in Main Loop

EEPROM_Erase_Sector(0x00,0x00); // Erase Flash Sector
EEPROM_Write_Byte(0x00, Data); // Write the Data - unsigned char

// Function Implementations

void EEPROM_Erase_Sector( unsigned int address, unsigned char data)
{
void EEPROM_Write_Byte( unsigned int address, unsigned char data)
/* Writes a byte of data to the EEPROM address passed to it */
{
if (FSTAT_FACCERR)        // If EEPROM access error flag is set
   FSTAT_FACCERR = 1;       // Then clear it

while(!FSTAT_FCBEF);      // Make sure command buffer is empty

EEPROM_ACCESS(address) = data;        // Write the data
FCMD = ERASE_SECTOR;      //

_asm NOP;                 // Wait at least 4 cycles before clearing FSTAT_FCBEF
_asm NOP;
_asm NOP;
_asm NOP;

FSTAT = 0x80;             // Clear command buffer empty flag

if (FSTAT_FACCERR)        // If EEPROM access error flag is set
   FSTAT_FACCERR = 1;       // Then clear it

if (FSTAT_FPVIOL)         // If EEPROM write error flag is set
    FSTAT_FPVIOL = 1;       // Then clear it

while (!FSTAT_FCCF);      // Wait for all commands to complete
}

void EEPROM_Write_Byte( unsigned int address, unsigned char data)
/* Writes a byte of data to the EEPROM address passed to it */
{
if (FSTAT_FACCERR)        // If EEPROM access error flag is set
   FSTAT_FACCERR = 1;       // Then clear it

while(!FSTAT_FCBEF);      // Make sure command buffer is empty

EEPROM_ACCESS(address) = data;        // Write the data
FCMD = BYTE_PROGRAM;      // Flash/EEPROM command to program a byte (0x20)

_asm NOP;                 // Wait at least 4 cycles before clearing FSTAT_FCBEF
_asm NOP;
_asm NOP;
_asm NOP;

FSTAT = 0x80;             // Clear command buffer empty flag

if (FSTAT_FACCERR)        // If EEPROM access error flag is set
   FSTAT_FACCERR = 1;       // Then clear it

if (FSTAT_FPVIOL)         // If EEPROM write error flag is set
    FSTAT_FPVIOL = 1;       // Then clear it

while (!FSTAT_FCCF);      // Wait for all commands to complete
}

Re: S08DZ EEPROM Sector Erase Problem

datamstr — Wed, 19 Jan 2011 00:22:03 GMT

Also, I am disabling interrupts during the Flash erase:

DisableInterrupts; // no interrupts during Flash Erase
EEPROM_Erase_Sector(0x00,0x00); // Erase Flash Sector

Thanks,

David

Re: S08DZ EEPROM Sector Erase Problem

Lundin — Wed, 19 Jan 2011 00:48:10 GMT

This is what I suspect:

while(!FSTAT_FCBEF); // Make sure command buffer is empty

When doing a burst write you want to do like the above, to make sure no pending commands are executed.

When doing a sector erase, I see no reason to do that. Instead you wait for FCCF at the end like your code already does.

It would seem that the CPU might get stuck in that loop. Apart from that, I can't see any problems in the code.

Also, the problem could be related to the prescaler and initialization of registers.