AVR Freaks

Hi all,

I'm using AVR-GCC version 4.9.4 with avr-libc version 2.0.0 and have run into a strange problem with reading a WORD (uint16_t) from eeprom.  Specifically, wrong data is returned.  Same code, compiler and libc works just fine on a 328P or MEGA2560.

This is the specific code that I use to read the EEPROM:

// send IR command from array
// *cmd   -> pointer to timing data array
void sendCmd (const uint16_t *cmd)
{
    uint16_t idx; // data block index
    uint16_t data; // read IR pulse width info

    while (busy); // in case ISR is busy

    idx = 0; // init index

    while (1) {

        data = eeprom_read_word ((const uint16_t *)(cmd + idx)); // read data

        idx++;

        if (data == 0) { // zero == end of table
            break;

        } else {

            cli(); // disable interrupts

            busy = 1; // flag ISR busy
            enable = (data >> 15); // bit 15 is IR on/off bit
            count = (data << 1); // (count * 2) for full cycle

            sei(); // enable interrupts

            while (busy); // wait while ISR is done sending

        }
    }
}

The data I am reading:

///////////////////////////////////////////////////////////////////////////////
// Sony camera shutter release code 0xB4B8F (focus and shoot)
///////////////////////////////////////////////////////////////////////////////
static const uint16_t shutter1[] EEMEM = {
    // header
    0x8060, 0x0018,
    // data
    0x8030, 0x0018, 0x8018, 0x0018, 0x8030, 0x0018, 0x8030, 0x0018, // B
    0x8018, 0x0018, 0x8030, 0x0018, 0x8018, 0x0018, 0x8018, 0x0018, // 4
    0x8030, 0x0018, 0x8018, 0x0018, 0x8030, 0x0018, 0x8030, 0x0018, // B
    0x8030, 0x0018, 0x8018, 0x0018, 0x8018, 0x0018, 0x8018, 0x0018, // 8
    0x8030, 0x0018, 0x8030, 0x0018, 0x8030, 0x0018, 0x8030, 0x01C8, // F
    // end of data block
    0x0000,
};

...and the ISR that does the work:

// IR carrier generator & timer
ISR (TIMER0_COMPA_vect)
{
    if (count) {
        count--;
        enable ? IO_INP = IR_BIT : 0;

    } else {
        busy = 0; // flag ISR is done
    }
}

As I said, on any other processor, this code works fine.  If I instead put the data into flash and use  pgm_read_word  it also works fine.  ONLY eeprom and ONLY reading a word fails.

Anyone have any ideas as to why this might be?

By the way, I've "solved" the problem by writing a generic eeprom read function (see below) but I shouldn't have to do this.

// universal eeprom READ
template <class T> T eepromRead (const T *addr)
{
    uint8_t x;
    uint8_t *ptr;
    T value;

    x = sizeof (T);
    ptr = ((uint8_t *)(void *)(&value));

    while (x--) {
        *(ptr + x) = (eeprom_read_byte ((uint8_t *)(addr) + x));
    }

    return value;
}

Any assistance will be greatly appreciated. Thanks!