C8051F023R Silicon Laboratories Inc, C8051F023R Datasheet - Page 192

• Manufacturer Part Number: C8051F023R
• Description: IC 8051 MCU 64K FLASH 64TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F02xr

Specifications of C8051F023R

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: EBI/EMI, SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 32
• Program Memory Size: 64KB (64K x 8)
• Program Memory Type: FLASH
• Ram Size: 4.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 8x8b, 8x10b; D/A 2x12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Other names: 336-1035-2

C8051F020/1/2/3
18.4.2. Clock Rate Register
192
Bits7-0:
R/W
Bit7
SMB0CR.[7:0]: SMBus0 Clock Rate Preset
The SMB0CR Clock Rate register controls the frequency of the serial clock SCL in master mode. The
8-bit word stored in the SMB0CR Register preloads a dedicated 8-bit timer. The timer counts up, and
when it rolls over to 0x00, the SCL logic state toggles.
The SMB0CR setting should be bounded by the following equation , where SMB0CR is the unsigned
8-bit value in register SMB0CR, and SYSCLK is the system clock frequency in Hz:
The resulting SCL signal high and low times are given by the following equations:
Using the same value of SMB0CR from above, the Bus Free Timeout period is given in the following
equation:
R/W
Bit6
Figure 18.9. SMB0CR: SMBus0 Clock Rate Register
SMB0CR
T
R/W
Bit5
HIGH
T
T
BFT
LOW


 


258 SMB0CR
288
=
10
R/W
Bit4


256 SMB0CR
–
–

---------------------------------------------------- -
256 SMB0CR
0.85
–
Rev. 1.4
–
R/W
Bit3

SYSCLK
SYSCLK  1.125 
 SYSCLK

 SYSCLK

R/W
Bit2


+
1
+
625ns
R/W
Bit1
R/W
Bit0
SFR Address:
00000000
Reset Value
0xCF