C8051F330DK Silicon Laboratories Inc, C8051F330DK Datasheet - Page 136

• Manufacturer Part Number: C8051F330DK
• Description: DEV KIT FOR C8051F330/F331
• Manufacturer: Silicon Laboratories Inc
• Type: MCUr

Specifications of C8051F330DK

• Contents: Evaluation Board, Power Supply, USB Cables, Adapter and Documentation
• Processor To Be Evaluated: C8051F33x
• Interface Type: RS-232
• Operating Supply Voltage: 7 V to 15 V
• Silicon Manufacturer: Silicon Labs
• Core Architecture: 8051
• Silicon Core Number: C8051F330
• Silicon Family Name: C8051F33x
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Silicon Laboratories C8051F330, C8051F331
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1264

C8051F330/1/2/3/4/5
15.4.1. SMBus Configuration Register
The SMBus Configuration register (SMB0CF) is used to enable the SMBus Master and/or Slave modes,
select the SMBus clock source, and select the SMBus timing and timeout options. When the ENSMB bit is
set, the SMBus is enabled for all master and slave events. Slave events may be disabled by setting the
INH bit. With slave events inhibited, the SMBus interface will still monitor the SCL and SDA pins; however,
the interface will NACK all received addresses and will not generate any slave interrupts. When the INH bit
is set, all slave events will be inhibited following the next START (interrupts will continue for the duration of
the current transfer).
The SMBCS1–0 bits select the SMBus clock source, which is used only when operating as a master or
when the Free Timeout detection is enabled. When operating as a master, overflows from the selected
source determine the absolute minimum SCL low and high times as defined in Equation 15.1. Note that the
selected clock source may be shared by other peripherals so long as the timer is left running at all times.
For example, Timer 1 overflows may generate the SMBus and UART baud rates simultaneously. Timer
configuration is covered in
The selected clock source should be configured to establish the minimum SCL High and Low times as per
Equation 15.1. When the interface is operating as a master (and SCL is not driven or extended by any
other devices on the bus), the typical SMBus bit rate is approximated by Equation 15.2.
140
Equation 15.1. Minimum SCL High and Low Times
Table 15.1. SMBus Clock Source Selection
SMBCS1
Section “18. Timers” on page 177
T
Equation 15.2. Typical SMBus Bit Rate
HighMin
0
0
1
1
BitRate
SMBCS0
=
T
0
1
0
1
LowMin
=
f
--------------------------------------------- -
ClockSourceOverflow
Rev. 1.7
=
Timer 2 High Byte Overflow
Timer 2 Low Byte Overflow
SMBus Clock Source
--------------------------------------------- -
f
ClockSourceOverflow
Timer 0 Overflow
Timer 1 Overflow
3
.
1