sm59d04g2 SyncMOS Technologies,Inc, sm59d04g2 Datasheet - Page 36

• Manufacturer Part Number: sm59d04g2
• Description: 8-bits Micro-controller 16kb+ Isp Flash & 1kb Ram Embedded
• Manufacturer: SyncMOS Technologies,Inc

10 Serial interface (UART)
The UART serial port is full duplex, meaning it can transmit and receive simultaneously. It is also
receive-buffered, meaning it can commence reception of a second byte before a previously received
byte has been read from the receive register. (However, if the first byte still hasn’t been read by the
time reception of the second byte is complete, one of the bytes will be lost). The serial port’s receive
and transmit registers are both accessed through SFR SBUF. Actually, SBUF is composed of two
separate registers, a transmit buffer and a receive buffer. Writing to SBUF loads the transmit
register, and reading SBUF accesses a physically separate receive register.
The serial port control and status register are in the SFR SCON. This register contains the mode
selection bits (SM0 and SM1), the SM2 bit for the multiprocessor modes (please see Subsection
10.1), the Receive Enable (REN); the 9
serial port interrupt bits (TI and RI).
The serial port can operate in the following 4 modes:
In all four modes, transmission is initiated by any instruction that uses SBUF as a destination
register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1. Reception is initiated
in the other modes by the incoming start bit if REN = 1.
10.1 Multiprocessor Communications
Mode 2 and 3 have a special provision for multiprocessor communications. In these modes, 9 data
bits are received. The 9
such that when the stop bit is received, the serial port interrupt will be activated only if RB8 = 1. This
feature is enabled by setting bit SM2 in SCON. This feature is used in multiprocessor systems as
follows.
Specifications subject to change without notice contact your sales representatives for the most recent information.
ISSFD-M031
Mode 0: Serial data enters and exits through RXD. TXD outputs the shift clock. 8 bits are
transmitted or received with LSB first. The baud rate is fixed at 1/6 the system frequency as
defined in Section 1.
Mode 1: 10 bits are transmitted (through TXD) or received (through RXD) with a start bit (=0),
then the 8 data bits with LSB first, finally a stop bit (=1). On the receiving side, the stop bit goes
into RB8 in SFR SCON. The baud rate is variable.
Mode 2: 11 bits are transmitted (through TXD) or received (through RXD) with a start bit (=0),
then the 8 data bits with LSB first, then a programmable 9
the transmitting side, the 9
example, the parity bit (P in the PSW) could be moved into TB8. On the receiving side , the 9
data bit goes into RB8 in SCON. The baud rate is programmable to either 1/32 or 1/16 of the
system frequency.
Mode 3: 11 bits are transmitted (through TXD) or received (through RXD) with a start bit (=0),
then the 8 data bits with LSB first, then a programmable 9
fact, Mode 3 is the same as Mode 2 in all respects except the baud rate. The baud rate in Mode
3 is variable.
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one goes into RB8. Then comes a stop bit. The port can be programmed
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data bit (TB8 in SCON) can be assigned the value of 0 or 1, or, for
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data bit for transmit and receive (TB8 and RB8); and the
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16KB+ ISP Flash & 1KB RAM embedded
data bit, finally a stop bit (=1). On
data bit, finally a stop bit (=1). In
Ver.C SM59D04G2 07/2009
8-Bits Micro-controller
SM59D04G2
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