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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.”