The DS4830 has a special bit， I2C_SPE， which does not change on I2C soft reset or external reset. This bit is used to identify the I2C bootloader function. The I2C_SPE bit is not writable in the application program; this bit can be written through UROM code only. The DS4830 has the dedicated slave address 34h， which is always visible on the active I2C slave interface and cannot be disabled without disabling the I2C slave interface. Slave address 34h is used to communicate directly with the UROM code. When the slave address 34h receives the Enter I2C Bootloader command， it sets the I2C_SPE bit. On reset， the UROM code checks the I2C_SPE bit. If I2C_SPE is clear， code execution jumps to the flash location 0000h in the application program. Otherwise， execution remains in UROM to execute utility functions. For more information， see the In-System Programming section in the user guide 5484， “DS4830 Optical Microcontroller User’s Guide.”