80C31X2 Datasheet, PDF (31/62 Pages) NXP Semiconductors – 80C51 8-bit microcontroller family 4K/8K/16K/32K ROM/OTP 128B/256B RAM low voltage 2.7 to 5.5 V, low power, high speed 30/33 MHz

Philips Semiconductors
80C51 8-bit microcontroller family
4K/8K/16K/32K ROM/OTP, low voltage (2.7 to 5.5 V),
low power, high speed (30/33 MHz)
Product data
P80C3xX2; P80C5xX2;
P87C5xX2
SCON Address = 98H
Bit Addressable
7
6
5
4
3
2
1
SM0/FE SM1
SM2
REN
TB8
RB8
Tl
Reset Value = 0000 0000B
0
Rl
(SMOD0 = 0/1)*
Symbol Position
Function
FE
SM0
SM1
SCON.7
SCON.7
SCON.6
SM2
SCON.5
REN
TB8
RB8
SCON.4
SCON.3
SCON.2
Tl
SCON.1
Rl
SCON.0
NOTES:
*SMOD0 is located at PCON.6.
**f_OSC = oscillator frequency
Framing Error bit. This bit is set by the receiver when an invalid stop bit is detected. The FE bit is not
cleared by valid frames but should be cleared by software. The SMOD0 bit must be set to enable
access to the FE bit.*
Serial Port Mode Bit 0, (SMOD0 must = 0 to access bit SM0)
Serial Port Mode Bit 1
SM0
0
0
1
1
SM1
0
1
0
1
Mode
0
1
2
3
Description
shift register
8-bit UART
9-bit UART
9-bit UART
Baud Rate**
f_OSC/12 (12-clk mode) or f_OSC/6 (6-clk mode)
variable
f_OSC/64 or f_OSC/32 or f_OSC/16 (6-clock mode) or
f_OSC/32 (12-clock mode)
variable
Enables the Automatic Address Recognition feature in Modes 2 or 3. If SM2 = 1 then Rl will not be set
unless the received 9th data bit (RB8) is 1, indicating an address, and the received byte is a Given or
Broadcast Address. In Mode 1, if SM2 = 1 then Rl will not be activated unless a valid stop bit was
received, and the received byte is a Given or Broadcast Address. 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, the 9th data bit that was received. In Mode 1, if 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.
SU01628
Figure 18. SCON: Serial Port Control Register
2003 Jan 24
31