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Writing union types to external EEPROM

Ruven H

Hi all,
Doe's anyone know how to write a union type to external parallel EEPROM (AT28C64)?

The union type is:
typedef union {
uchar handle :1;
uchar input_status;
uchar intrnl_event;
uchar rcv_data[8];
uint measurement;
Time time;
Date date;
} rcvMSG;

I know how to write byte by byte but not this one. I also configured the external pointer to be rcvMSG instead of char but without luck.

  • 0

    There is no way OTHER than writing byte-by-byte on the 8051. So, if you know how to write byte-by-byte to the external EEPROM, create a function that writes multiple bytes one after the other. For example:

    void write_to_EEPROM (
  void *buffer,
  unsigned EEPROM_address,
  unsigned buffer_len)
{
unsigned char *bp;

for (bp = buffer; buffer_len; buffer_len--, bp++, EEPROM_address++)
  {
  // Write *bp to EEPROM_address
  }
}

    Then, you can write stuff into the EEPROM as follows:

    rcvMSG union_var;

write_to_EEPROM (&union_var, 0x1000, sizeof (rcvMSG));

    This function call writes union_var to address 0x1000 (4096) in the EEPROM.

    Jon

  • 0 in reply to Jon Ward

    Thanks a lot Jon. U R the best!

  • 0 in reply to Ruven H

    Most EEPROMs have a write buffer. You can take advantage of that to accelerate block writes to EEPROM. However if speed is not an issue it's not worth the effort.
    Regards,
    - Mike