SH79F166APSLASH044PR datasheet(79/113 Pages) SINOWEALTH

79 / 113 page

SH79F166A

Mode2: 9-Bit EUART, Fixed Baud Rate, Asynchronous Full-Duplex

This mode provides the 11 bits full duplex asynchronous communication. The 11 bit consists of one start bit (logical 0), 8 data

bits (LSB first), a programmable 9

th data bit, and a stop bit (logical 1). Mode 2 supports multiprocessor communications and

hardware address recognition (Refer to Multiprocessor Communication Section for details). When data is transmitted, the 9

data bit (TB8 in SCON) can be assigned the value of 0 or 1, for example, the parity bit P in the PSW or used as data/address

flag in multiprocessor communications. When data is received, the 9

th data bit goes into RB8 and the stop bit is not saved. The

baud rate is programmable to either 1/32 or 1/64 of the system working frequency, as determined by the SMOD bit in PCON.

The functional block diagram is shown below:

SERIAL

CONTROLLER

TX CLOCK

TX START

TX SHIFT

RX CLOCK

LOAD SBUF

RX START

RX SHIFT

TXD

Serial Port Interrupt

PARIN

LOAD

CLOCK

SOUT

CLOCK

SIN

PAROUT

RXD

Read SBUF

Internal

Data Bus

Receive Shift Register

Internal

Data Bus

1-TO-0

DETECTOR

Write to SBUF

BIT

DETECTOR

SBUF

RB8

Transmit Shift Register

STOP

START

SAMPLE

TB8

SMOD

System Clock

Transmission begins with a “write to SBUF” signal, the “write to SBUF” signal also loads TB8 into the 9

th bit position of the

transmit shift register. Transmission actually commences at the next system clock following the next rollover in the divide-by-16

counter (thus, the bit times are synchronized to the divide-by-16 counter, not to the “write to SUBF” signal). The start bit is firstly

put out on TxD pin, then are the 9 bits of data. After all 9 bits of data in the transmit shift register are transmitted, the stop bit is

put out on the TxD pin, and the TI flag is set at the same time, this will be at the 11

th rollover of the divide-by-16 counter after a

write to SBUF.

Write to SBUF

Shift CLK

Send Timing of Mode 2

TxD

Start

Stop

SH79F166AP/044PR Datasheet(PDF) 79 Page - SINOWEALTH Electronic Ltd

SH79F166AP/044PR Datasheet(HTML) 79 Page - SINOWEALTH Electronic Ltd

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