RSSI 1 RSSI 2 ADC 1 Auxiliary DAC Outputs ADC 2 MUX 10-bit ADC DVSS Bias Generator DAC RAM C-BUS Serial Interface Chip-Select Receive Data C-BUS Interface Single or Two-Point Mod Tx Outputs VBIAS Aux DACs 10-bit DAC 10-bit ADC 10-bit DAC MUX 10-bit DAC Digital 2V5 Regulator 10-bit DAC IOVDD DVDD 3.0 to 3.6 volt Input Multiplexed Auxiliary ADC Inputs AIS Raw Tx MUX Message Buffer GMSK Modulator AIS Burst HDLC/ NRZI Encoder Serial Clock Command Data Tx Channel Registers AIS Raw Rx1 Power Control Rx Inputs GMSK Demodulator AIS Burst HDLC/ NRZI Decoder Message Buffer Rx Channel 1 Internal Systems Control BIAS MUX FSK Demodulator Message Buffer FSK Rx Channel System Clock 1 System Clock 2 Rx 2 GMSK Demodulator BIAS AVDD HDLC/ NRZI Decoder Message Buffer Rx Channel 2 AIS Raw Sample Timer Analogue 2V5 regulator Interrupt Generator Main Clock Digital PLL Boot Control EEPROM SPI Port Boot Enable 1 and 2 SPI Port for FI Load Xtal Clock AVSS IOVDD 3.0 to 3.6 volt input AIS Burst Interrupt Xtal/Clock I/O Synthesised System Clocks