C8051F121 Silicon Laboratories Inc, C8051F121 Datasheet - Page 265

• Manufacturer Part Number: C8051F121
• Description: IC 8051 MCU FLASH 128K 64TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F12xr

Specifications of C8051F121

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 100MHz
• 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: 128KB (128K x 8)
• Program Memory Type: FLASH
• Ram Size: 8.25K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 8x8b, 8x12b; 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: -

C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Setting the SMBus0 Free Timer Enable bit (FTE, SMB0CN.1) to logic 1 enables the timer in SMB0CR.
When SCL goes high, the timer in SMB0CR counts up. A timer overflow indicates a free bus timeout: if
SMBus0 is waiting to generate a START, it will do so after this timeout. The bus free period should be less
than 50 µs (see SFR Definition 19.2, SMBus0 Clock Rate Register).
When the TOE bit in SMB0CN is set to logic 1, Timer 3 is used to detect SCL low timeouts. If Timer 3 is
enabled (see
Section “23.2. Timer 2, Timer 3, and Timer 4” on page 317
), Timer 3 is forced to reload
when SCL is high, and forced to count when SCL is low. With Timer 3 enabled and configured to overflow
after 25 ms (and TOE set), a Timer 3 overflow indicates a SCL low timeout; the Timer 3 interrupt service
routine can then be used to reset SMBus0 communication in the event of an SCL low timeout.
Rev. 1.4
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