C8051F321 Silicon Laboratories Inc, C8051F321 Datasheet - Page 184

• Manufacturer Part Number: C8051F321
• Description: IC 8051 MCU 16K FLASH 28MLP
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F32xr

Specifications of C8051F321

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 21
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 2.25K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 13x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-VQFN Exposed Pad, 28-HVQFN, 28-SQFN, 28-DHVQFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

C8051F320/1
184
Bit7:
Bit6:
Bit5:
Bit4:
Bit3:
Bit2:
Bit1:
Bit0:
MASTER TXMODE
Bit7
R
MASTER: SMBus Master/Slave Indicator.
This read-only bit indicates when the SMBus is operating as a master.
0: SMBus operating in Slave Mode.
1: SMBus operating in Master Mode.
TXMODE: SMBus Transmit Mode Indicator.
This read-only bit indicates when the SMBus is operating as a transmitter.
0: SMBus in Receiver Mode.
1: SMBus in Transmitter Mode.
STA: SMBus Start Flag.
Write:
0: No Start generated.
1: When operating as a master, a START condition is transmitted if the bus is free (If the bus is not
free, the START is transmitted after a STOP is received or a timeout is detected). If STA is set by soft-
ware as an active Master, a repeated START will be generated after the next ACK cycle.
Read:
0: No Start or repeated Start detected.
1: Start or repeated Start detected.
STO: SMBus Stop Flag.
Write:
0: No STOP condition is transmitted.
1: Setting STO to logic 1 causes a STOP condition to be transmitted after the next ACK cycle. When
the STOP condition is generated, hardware clears STO to logic 0. If both STA and STO are set, a
STOP condition is transmitted followed by a START condition.
Read:
0: No Stop condition detected.
1: Stop condition detected (if in Slave Mode) or pending (if in Master Mode).
ACKRQ: SMBus Acknowledge Request
This read-only bit is set to logic 1 when the SMBus has received a byte and needs the ACK bit to be
written with the correct ACK response value.
ARBLOST: SMBus Arbitration Lost Indicator.
This read-only bit is set to logic 1 when the SMBus loses arbitration while operating as a transmitter.
A lost arbitration while a slave indicates a bus error condition.
ACK: SMBus Acknowledge Flag.
This bit defines the out-going ACK level and records incoming ACK levels. It should be written each
time a byte is received (when ACKRQ=1), or read after each byte is transmitted.
0: A "not acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in
Receiver Mode).
1: An "acknowledge" has been received (if in Transmitter Mode) OR will be transmitted (if in
Receiver Mode).
SI: SMBus Interrupt Flag.
This bit is set by hardware under the conditions listed in Table 16.3. SI must be cleared by software.
While SI is set, SCL is held low and the SMBus is stalled.
Bit6
R
Figure 16.6. SMB0CN: SMBus Control Register
STA
R/W
Bit5
STO
R/W
Bit4
ACKRQ ARBLOST
Rev. 1.1
Bit3
R
Bit2
R
ACK
R/W
Bit1
SFR Address:
R/W
Bit0
SI
0xC0
00000000
Addressable
Reset Value
Bit