eeprom driver code c++ overlapping

Question

im trying to write driver for EEPROM (24LC64):

• page size: 32 byte
• capacity: 8KB (64Kbit)

definition code:

#define E24LC64_WRITE_PAGE_SIZE 32
#define E24LC64_TOTAL_SIZE 8000
#define E24LC64_WRITE_DELAY_MS 5

class public function:

uint32_t E24LC64::eeprom_write(uint16_t address, const uint8_t* buff,int32_t length){
                        //          19      this is test. trimmed?          22
uint8_t page_head_addr ;
int32_t sent_length;
uint32_t err_val = TWI_SUCCESS;
//do we need to write next page:
while ( (length>0) && (TWI_SUCCESS == err_val) ){
    err_val = _PageWrite(address, buff, length);
    page_head_addr = (address % E24LC64_WRITE_PAGE_SIZE);
    sent_length = E24LC64_WRITE_PAGE_SIZE - page_head_addr;
    length  -=  sent_length;
    address +=  sent_length;
    buff += sent_length;
}
return err_val;

}

class private function to write pages

/*
    this function write pages
    it trims the right bytes if they exceed the page boundary.
    max length = EEPROM page size.
*/
uint32_t E24LC64::_PageWrite(uint16_t ROMADDR, const uint8_t *buff, uint8_t length){
    uint8_t send_length;

    uint8_t page_head_addr = (ROMADDR % E24LC64_WRITE_PAGE_SIZE);

    if ( (page_head_addr + length)>E24LC64_WRITE_PAGE_SIZE){
        send_length = E24LC64_WRITE_PAGE_SIZE - page_head_addr; //trim the extra
    }else{
        send_length = length;
    }

    twi_packet_t packet;
    packet.buffer = (void*) buff;
    packet.length = send_length;
    packet.chip = _I2Caddr;
    packet.addr[0] = uint8_t(ROMADDR & 0xff00);
    packet.addr[1] = uint8_t((ROMADDR >> 8) & 0x00ff);
    packet.addr_length = 2;
    uint32_t err_val = twi_master_write(_pTWI, &packet);

    if (err_val == TWI_SUCCESS)
        delay_ms(E24LC64_WRITE_DELAY_MS);
    return err_val;


}

user call:

E24LC64 ext_eeprom(TWI0, 0x50);
char mystr[] = "this is test. trimmed?";
ext_eeprom.eeprom_write(19,(uint8_t*)mystr,strlen(mystr))

the error: the function eeprom seems to write back to address 19!

so it looks like this code didnt execute?!

address +=  sent_length;

can you spot the logical error that makes the page write overlapping?

Answer 1

packet.addr[0] = uint8_t(ROMADDR & 0xff00);
packet.addr[1] = uint8_t((ROMADDR >> 8) & 0x00ff);

This is probably not what you want. Notice that you are masking the low byte of ROMADDR in both lines which results in addr[0] being 0x00 every time.

Try

packet.addr[0] = (uint8_t)(ROMADDR >> 8);  // High byte of ROMADDR
packet.addr[1] = (uint8_t)(ROMADDR); // Low byte of ROMADDR