P87LPC768FD NXP Semiconductors, P87LPC768FD Datasheet - Page 42

• Manufacturer Part Number: P87LPC768FD
• Description: MCU 8-Bit 87LP 80C51 CISC 4KB EPROM 5V 20-Pin SO Tube
• Manufacturer: NXP Semiconductors

Specifications of P87LPC768FD

• Package: 20SO
• Device Core: 80C51
• Family Name: 87LP
• Maximum Speed: 20 MHz
• Ram Size: 128 Byte
• Program Memory Size: 4 KB
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Program Memory Type: EPROM
• Number Of Programmable I/os: 18
• Interface Type: I2C/UART
• On-chip Adc: 4-chx8-bit
• Operating Temperature: -40 to 85 °C
• Number Of Timers: 2

Philips Semiconductors
Serial Port Control Register (SCON)
The serial port control and status register is the Special Function
Register SCON, shown in Figure 31. This register contains not only
the mode selection bits, but also the 9th data bit for transmit and
receive (TB8 and RB8), and the serial port interrupt bits (TI and RI).
The Framing Error bit (FE) allows detection of missing stop bits in
the received data stream. The FE bit shares the bit position SCON.7
2002 Mar 12
Low power, low price, low pin count (20 pin) microcontroller
with 4 kB OTP 8-bit A/D, Pulse Width Modulator
SCON
BIT
SCON.7
SCON.7
SCON. 6
SCON.5
SCON.4
SCON.3
SCON.2
SCON.1
SCON.0
Address: 98h
Bit Addressable
SM0, SM1
SYMBOL
REN
SM0
SM1
SM2
RB8
TB8
FE
0 0
0 1
1 0
1 1
RI
TI
SM0/FE
7
FUNCTION
Framing Error. This bit is set by the UART receiver when an invalid stop bit is detected. Must be
cleared by software. The SMOD0 bit in the PCON register must be 1 for this bit to be accessible.
See SM0 bit below.
With SM1, defines the serial port mode. The SMOD0 bit in the PCON register must be 0 for this bit
to be accessible. See FE bit above.
With SM0, defines the serial port mode (see table below).
UART Mode
0: shift register
1: 8-bit UART
2: 9-bit UART
3: 9-bit UART
Enables the multiprocessor communication feature in Modes 2 and 3. In Mode 2 or 3, if SM2 is set
to 1, then Rl will not be activated if the received 9th data bit (RB8) is 0. In Mode 1, if SM2=1 then RI
will not be activated if a valid stop bit was not received. In Mode 0, SM2 should be 0.
Enables serial reception. Set by software to enable reception. Clear by software to disable reception.
The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software as desired.
In Modes 2 and 3, is the 9th data bit that was received. In Mode 1, it SM2=0, RB8 is the stop bit that
was received. In Mode 0, RB8 is not used.
Transmit interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or at the beginning
of the stop bit in the other modes, in any serial transmission. Must be cleared by software.
Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or halfway through
the stop bit time in the other modes, in any serial reception (except see SM2). Must be cleared by
software.
SM1
6
Figure 31. Serial Port Control Register (SCON)
SM2
5
REN
Baud Rate
CPU clock/6
Variable (see text)
CPU clock/32 or CPU clock/16
Variable (see text)
4
40
TB8
3
with the SM0 bit. Which bit appears in SCON at any particular time
is determined by the SMOD0 bit in the PCON register. If SMOD0 =
0, SCON.7 is the SM0 bit. If SMOD0 = 1, SCON.7 is the FE bit.
Once set, the FE bit remains set until it is cleared by software. This
allows detection of framing errors for a group of characters without
the need for monitoring it for every character individually.
RB8
2
TI
1
RI
0
Reset Value: 00h
P87LPC768
Preliminary data
SU01157