C8051F336/7/8/9
19.3.Programmable Internal Low-Frequency (L-F) Oscillator ................................ 120
19.3.1.Calibrating the Internal L-F Oscillator..................................................... 120
19.4.External Oscillator Drive Circuit...................................................................... 121
19.4.1.External Crystal Example....................................................................... 123
19.4.2.External RC Example............................................................................. 125
19.4.3.External Capacitor Example................................................................... 125
20.Port Input/Output.................................................................................................. 126
20.1.Port I/O Modes of Operation........................................................................... 127
20.1.1.Port Pins Configured for Analog I/O....................................................... 127
20.1.2.Port Pins Configured For Digital I/O....................................................... 128
20.1.3.Interfacing Port I/O to 5V Logic.............................................................. 128
20.2.Assigning Port I/O Pins to Analog and Digital Functions................................ 129
20.2.1.Assigning Port I/O Pins to Analog Functions ......................................... 129
20.2.2.Assigning Port I/O Pins to Digital Functions........................................... 130
20.2.3.Assigning Port I/O Pins to External Digital Event Capture Functions .... 130
20.3.Priority Crossbar Decoder .............................................................................. 131
20.4.Port I/O Initialization ....................................................................................... 133
20.5.Port Match ...................................................................................................... 136
20.6.Special Function Registers for Accessing and Configuring Port I/O .............. 138
21.SMBus ................................................................................................................... 145
21.1.Supporting Documents................................................................................... 145
21.2.SMBus Configuration...................................................................................... 146
21.3.SMBus Operation ........................................................................................... 146
21.3.1.Transmitter Vs. Receiver........................................................................ 147
21.3.2.Arbitration............................................................................................... 147
21.3.3.Clock Low Extension.............................................................................. 148
21.3.4.SCL Low Timeout................................................................................... 148
21.3.5.SCL High (SMBus Free) Timeout .......................................................... 148
21.4.Using the SMBus............................................................................................ 148
21.4.1.SMBus Configuration Register............................................................... 149
21.4.2.SMB0CN Control Register ..................................................................... 152
21.4.2.1.Software ACK Generation ............................................................. 152
21.4.2.2.Hardware ACK Generation............................................................ 152
21.4.3.Hardware Slave Address Recognition ................................................... 155
21.4.4.Data Register ......................................................................................... 157
21.5.SMBus Transfer Modes.................................................................................. 158
21.5.1.Write Sequence (Master) ....................................................................... 158
21.5.2.Read Sequence (Master)....................................................................... 159
21.5.3.Write Sequence (Slave) ......................................................................... 160
21.5.4.Read Sequence (Slave)......................................................................... 161
21.6.SMBus Status Decoding................................................................................. 161
22.UART0.................................................................................................................... 166
22.1.Enhanced Baud Rate Generation................................................................... 167
22.2.Operational Modes ......................................................................................... 168
Rev. 0.2
5
SILICON [ SILICON ]
