C8051F321 Silicon Laboratories Inc, C8051F321 Datasheet - Page 134

• 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
14.3. General Purpose Port I/O
Port pins that remain unassigned by the Crossbar and are not used by analog peripherals can be used for general pur-
pose I/O. Ports3-0 are accessed through corresponding special function registers (SFRs) that are both byte address-
able and bit addressable. When writing to a Port, the value written to the SFR is latched to maintain the output data
value at each pin. When reading, the logic levels of the Port's input pins are returned regardless of the XBRn settings
(i.e., even when the pin is assigned to another signal by the Crossbar, the Port register can always read its correspond-
ing Port I/O pin). The exception to this is the execution of the read-modify-write instructions. The read-modify-write
instructions when operating on a Port SFR are the following: ANL, ORL, XRL, JBC, CPL, INC, DEC, DJNZ and
MOV, CLR or SETB, when the destination is an individual bit in a Port SFR. For these instructions, the value of the
register (not the pin) is read, modified, and written back to the SFR.
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