
4.2001; Rev. 1.3
CYGNAL Integrated Products, Inc. 
 2001
Page 5
C8051F000/1/2/5/6/7 
C8051F010/1/2/5/6/7 
PRELIMINARY 
Figure 15.6.  P0: Port0 Register......................................................................................................................108 
Figure 15.7.  PRT0CF: Port0 Configuration Register.....................................................................................108 
Figure 15.8.  P1: Port1 Register......................................................................................................................109 
Figure 15.9.  PRT1CF: Port1 Configuration Register.....................................................................................109 
Figure 15.10.  PRT1IF: Port1 Interrupt Flag Register ....................................................................................109 
Figure 15.11.  P2: Port2 Register....................................................................................................................110 
Figure 15.12.  PRT2CF: Port2 Configuration Register...................................................................................110 
Figure 15.13.  P3: Port3 Register....................................................................................................................111 
Figure 15.14.  PRT3CF: Port3 Configuration Register...................................................................................111 
Table 15.2.  Port I/O DC Electrical Characteristics........................................................................................111 
16. SMBus...............................................................................................................................112 
Figure 16.1.  SMBus Block Diagram..............................................................................................................112 
Figure 16.2.  Typical SMBus Configuration...................................................................................................113 
16.1. Supporting Documents.........................................................................................................................113 
16.2. Operation..............................................................................................................................................114 
Figure 16.3.  SMBus Transaction....................................................................................................................114 
16.3. Arbitration............................................................................................................................................115 
16.4. Clock Low Extension...........................................................................................................................115 
16.5. Timeouts...............................................................................................................................................115 
16.6. SMBus Special Function Registers......................................................................................................115 
Figure 16.4. SMB0CN: SMBus Control Register...........................................................................................117 
Figure 16.5.  SMB0CR: SMBus Clock Rate Register.....................................................................................118 
Figure 16.6.  SMB0DAT: SMBus Data Register............................................................................................119 
Figure 16.7.  SMB0ADR: SMBus Address Register ......................................................................................119 
Figure 16.8.  SMB0STA: SMBus Status Register...........................................................................................120 
Table 16.1.  SMBus Status Codes...................................................................................................................121 
17. SERIAL PERIPHERAL INTERFACE BUS................................................................122 
Figure 17.1.  SPI Block Diagram....................................................................................................................122 
Figure 17.2.  Typical SPI Interconnection ......................................................................................................123 
17.1. Signal Descriptions ..............................................................................................................................123 
17.2. Operation..............................................................................................................................................124 
Figure 17.3.  Full Duplex Operation...............................................................................................................124 
17.3. Serial Clock Timing.............................................................................................................................125 
Figure 17.4.  Data/Clock Timing Diagram......................................................................................................125 
17.4. SPI Special Function Registers ............................................................................................................126 
Figure 17.5.  SPI0CFG: SPI Configuration Register.......................................................................................126 
Figure 17.6.  SPI0CN: SPI Control Register...................................................................................................127 
Figure 17.7.  SPI0CKR: SPI Clock Rate Register...........................................................................................128 
Figure 17.8.  SPI0DAT: SPI Data Register.....................................................................................................128 
18. UART................................................................................................................................129 
Figure 18.1.  UART Block Diagram...............................................................................................................129 
18.1. UART Operational Modes...................................................................................................................130 
Table 18.1.  UART Modes..............................................................................................................................130 
Figure 18.2.  UART Mode 0 Interconnect......................................................................................................130 
Figure 18.3.  UART Mode 0 Timing Diagram................................................................................................130 
Figure 18.4.  UART Mode 1 Timing Diagram................................................................................................131 
Figure 18.5.  UART Modes 1, 2, and 3 Interconnect Diagram.......................................................................132 
Figure 18.6.  UART Modes 2 and 3 Timing Diagram ....................................................................................132 
18.2. Multiprocessor Communications..........................................................................................................133 
Figure 18.7.  UART Multi-Processor Mode Interconnect Diagram................................................................133 
Table 18.2.  Oscillator Frequencies for Standard Baud Rates.........................................................................134 
Figure 18.8.  SBUF: Serial (UART) Data Buffer Register..............................................................................134 
Figure 18.9.  SCON: Serial Port Control Register ..........................................................................................135 
19. TIMERS............................................................................................................................136