/* ... */

/*
 * Connect to the EEPROM. 0x50 is the device address.
 * smbus_fp is a file pointer into the SMBus device.
 */
ioctl(smbus_fp, 0x50, slave);

/* Write a byte (0xAB) at memory offset 0 on the EEPROM */
i2c_smbus_write_byte_data(smbus_fp, 0, 0xAB);

/*
 * This is the corresponding transaction observed
 * on the bus after the write:
 * S 0x50 Wr [A] 0 [A] 0xAB [A] P
 *
 * S is the start bit, 0x50 is the 7-bit slave address (0101000b),
 * Wr is the write command (0b), A is the Accept bit (or
 * acknowledgment) received by the host from the slave, 0 is the
 * address offset on the slave device where the byte is to be
 * written, 0xAB is the data to be written, and P is the stop bit.
 * The data enclosed within [] is sent from the slave to the
 * host, while the rest of the bits are sent by the host to the
 * slave.
 */

/* Read a byte from offset 0 on the EEPROM */
res = i2c_smbus_read_byte_data(smbus_fp, 0);

/*
 * This is the corresponding transaction observed
 * on the bus after the read:
 * S 0x50 Wr [A] 0 [A] S 0x50 Rd [A] [0xAB] NA P
 *
 * The explanation of the bits is the same as before, except that
 * Rd stands for the Read command (1b), 0xAB is the data received
 * from the slave, and NA is the Reverse Accept bit (or the
 * acknowledgment sent by the host to the slave).
 */