C8051F38C-GMR 데이터 시트보기 (PDF) - Silicon Laboratories

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C8051F38C-GMR

Full Speed USB Flash MCU Family

Silicon Laboratories 

C8051F380/1/2/3/4/5/6/7/C

23. UART0

UART0 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART.

Enhanced baud rate support allows a wide range of clock sources to generate standard baud rates (details

in Section “23.1. Enhanced Baud Rate Generation” on page 233). Received data buffering allows UART0

to start reception of a second incoming data byte before software has finished reading the previous data

byte.

UART0 has two associated SFRs: Serial Control Register 0 (SCON0) and Serial Data Buffer 0 (SBUF0).

The single SBUF0 location provides access to both transmit and receive registers. Writes to SBUF0

always access the Transmit register. Reads of SBUF0 always access the buffered Receive register;

it is not possible to read data from the Transmit register.

With UART0 interrupts enabled, an interrupt is generated each time a transmit is completed (TI0 is set in

SCON0), or a data byte has been received (RI0 is set in SCON0). The UART0 interrupt flags are not

cleared by hardware when the CPU vectors to the interrupt service routine. They must be cleared manually

by software, allowing software to determine the cause of the UART0 interrupt (transmit complete or receive

complete).

UART Baud

Rate Generator

SFR Bus

Write to

SBUF

TB8

SET

D

Q

CLR

SBUF

(TX Shift)

Zero Detector

Stop Bit

Start

Tx Clock

Shift

Tx Control

Data

Tx IRQ Send

SCON

TI

RI

TX Crossbar

Serial

Port

Interrupt

Port I/O

Rx Clock

Start

Shift

Rx IRQ

Rx Control

0x1FF

RB8

Load

SBUF

Input Shift Register

(9 bits)

Load SBUF

SBUF

(RX Latch)

Read

SBUF

SFR Bus

RX Crossbar

Figure 23.1. UART0 Block Diagram

232

Rev. 1.4

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