SM89516B datasheet(35/49 Pages) SYNCMOS

35 / 49 page

SM89516B

8-Bit Micro-controller

64KB Flash

& 1KB RAM embedded

Specifications subject to change without notice contact your sales representatives for the most recent information.

ISSFD-M087

Ver D SM89516B 08/07/2015

- 35 -

The serial port is full duplex, can transmit and receive simultaneously. The serial port receive and transmit share

the same SFR – SBUF, but actually there is two SBUF in the chip, one is for transmit and the other is for receive.

The serial port can be operated in 4 different modes.

8.1.1

Mode 0

Pin RXD serves as input and output. TXD outputs the shift clock. 8 bits are transmitted with LSB first. The baud

rate is fixed at 1/12 of the crystal frequency. Reception is initialized in Mode 0 by setting the flags in SCON as

follows: RI = 0 and REN = 1. In other modes, a start bit when REN = 1 starts receiving serial data. As shown in Fig.

8-1 and Fig. 8-2

Fig. 8-1: Transmit mode 0

Fig. 8-2: Receive mode 0

8.1.2

Mode 1

Pin RXD serves as input, and TXD serves as serial output. No external shift clock is used, 10 bits are transmitted: a

start bit (always 0), 8 data bits (LSB first), and a stop bit (always 1). On receive, a start bit synchronizes the

transmission, 8 data bits are available by reading SBUF, and stop bit sets the flag RB8 in the Special Function

in Fig. 8-3 and Fig. 8-4

Fig. 8-3: Transmit mode 1

SM89516B Datasheet(PDF) 35 Page - SyncMOS Technologies,Inc