C8051F34B-GQ Silicon Laboratories Inc, C8051F34B-GQ Datasheet - Page 191

• Manufacturer Part Number: C8051F34B-GQ
• Description: IC 8051 MCU 32K FLASH 32LQFP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F34xr

Specifications of C8051F34B-GQ

• Program Memory Type: FLASH
• Program Memory Size: 32KB (32K x 8)
• Package / Case: 32-LQFP
• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 48MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 25
• Ram Size: 2.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 17x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: C8051F3x
• Core: 8051
• Data Bus Width: 8 bit
• Data Ram Size: 2.25 KB
• Interface Type: I2C/SMBus/SPI/UART/USB
• Maximum Clock Frequency: 48 MHz
• Number Of Programmable I/os: 25
• Number Of Timers: 4
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: KSK-SL-F34X, KSK-SL-TOOLSTICK, PK51, CA51, A51, ULINK2
• Development Tools By Supplier: C8051F340DK
• Minimum Operating Temperature: - 40 C
• Package: 32LQFP
• Device Core: 8051
• Family Name: C8051F34x
• Maximum Speed: 48 MHz
• Operating Supply Voltage: 3.3|5 V
• On-chip Adc: 17-chx10-bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: 336-1748 - ADAPTER TOOLSTICK FOR C8051F34X
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1534

17.3.2. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different
speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow
slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line
LOW to extend the clock low period, effectively decreasing the serial clock frequency.
17.3.3. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, no further communication is possible. Furthermore,
the master cannot force the SCL line high to correct the error condition. To solve this problem, the SMBus
protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than
25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communi-
cation no later than 10 ms after detecting the timeout condition.
When the SMBTOE bit in SMB0CF is set, Timer 3 is used to detect SCL low timeouts. Timer 3 is forced to
reload when SCL is high, and allowed to count when SCL is low. With Timer 3 enabled and configured to
overflow after 25 ms (and SMBTOE set), the Timer 3 interrupt service routine can be used to reset (disable
and re-enable) the SMBus in the event of an SCL low timeout.
17.3.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus
is designated as free. When the SMBFTE bit in SMB0CF is set, the bus will be considered free if SCL and
SDA remain high for more than 10 SMBus clock source periods. If the SMBus is waiting to generate a
Master START, the START will be generated following this timeout. Note that a clock source is required for
free timeout detection, even in a slave-only implementation.
17.4. Using the SMBus
The SMBus can operate in both Master and Slave modes. The interface provides timing and shifting con-
trol for serial transfers; higher level protocol is determined by user software. The SMBus interface provides
the following application-independent features:
•
•
•
•
•
•
•
SMBus interrupts are generated for each data byte or slave address that is transferred. When transmitting,
this interrupt is generated after the ACK cycle so that software may read the received ACK value; when
receiving data, this interrupt is generated before the ACK cycle so that software may define the outgoing
ACK value. See
sequences.
Interrupts are also generated to indicate the beginning of a transfer when a master (START generated), or
the end of a transfer when a slave (STOP detected). Software should read the SMB0CN (SMBus Control
register) to find the cause of the SMBus interrupt. The SMB0CN register is described in
“17.4.2. SMB0CN Control Register” on page 195
ence.
Byte-wise serial data transfers
Clock signal generation on SCL (Master Mode only) and SDA data synchronization
Timeout/bus error recognition, as defined by the SMB0CF configuration register
START/STOP timing, detection, and generation
Bus arbitration
Interrupt generation
Status information
Section “17.5. SMBus Transfer Modes” on page 198
C8051F340/1/2/3/4/5/6/7/8/9/A/B/C/D
Rev. 1.3
; Table 17.4 provides a quick SMB0CN decoding refer-
for more details on transmission
Section
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