SH79F024XU datasheet(61/92 Pages) SINOWEALTH

61 / 92 page

SH79F

SH79F082

082

Reception is enabled only if REN is high. The serial port actually starts the receiving of serial data, with the detection of a

falling edge on the RxD pin. For this purpose RxD is sampled at the rate of 16 times baud rate. When a falling edge is

detected, the divide-by-16 counter is immediately reset. This helps to align the bit boundaries with the rollovers of the divide-

by-16 counter. The 16 states of the counter divide each bit time into 16ths. The bit detector samples the value of RxD at the

7th, 8th and 9th counter state of each bit time. The value accepted is the value that was seen in at least 2 of the 3 samples.

This is done for noise rejection. If the first bit detected after the falling edge of RxD pin is not 0, which indicates an invalid

start bit, and the reception is immediately aborted. The receive circuits are reset and again looks for a falling edge in the RxD

line. If a valid start bit is detected, then the rest of the bits are also detected and shifted into the shift register.

After shifting in 9 data bits and the stop bit, the SBUF and RB8 are loaded and RI is set if the following conditions are met:

1. RI must be 0

2. Either SM2 = 0, or the received 9th bit = 1 and the received byte accords with Given Address

If these conditions are met, then the 9th bit goes to RB8, the 8 data bits go into SBUF and RI is set. Otherwise the received

frame may be lost.

At the time, the receiver goes back to looking for another falling edge on the RxD pin. And the user should clear RI by

software for further reception.

Shift CLK

RxD

Bit Sample

Start

Stop

Receive Timing of Mode 2

Mode

Mode 3

3:::: 9-Bit

9-Bit

9-Bit EUART,

EUART,

EUART, Variable

Variable

Variable Baud

Baud

Baud Rate

Rate

Rate,,,, Asynchronous

Asynchronous

Asynchronous Full-Duplex

Full-Duplex

Mode 3 uses transmission protocol of the Mode 2 and baud rate generation of the Mode 1.

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

Timer 1 Overflow

SH79F024XU Datasheet(PDF) 61 Page - SINOWEALTH Electronic Ltd

SH79F024XU Datasheet(HTML) 61 Page - SINOWEALTH Electronic Ltd

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92

Datasheet Download

Link URL