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Rev. 1.00
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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
UART Serial Interfaces – UART0 and UART1
UART Serial Interfaces – UART0 and UART1
S0CON Register – UART0 Control register
SFR Address: 98h
Bit
7
6
5
4
3
2
1
0
Name
SM0
SM1
SM�0
REN0
TB80
RB80
TI0
RI0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
0
0
0
0
0
0
0
Bit 7~6
SM0,
SM1:
UART0 Operating mode select bits
00: Mode 0
01: Mode 1
10: Mode 2
11: Mode 3
The following table illustrates the corresponding mode descriptions and baud rates. In
mode1 and mode 3, the variable baud rate is dependent on the system clock, the baud
rate clock source and the prescaler selections. Operating mode details are described
elsewhere.
Mode
Mode Name
Baud Rate
Synchronisation
Mode 0
8-bit shift �egiste�
f
SYS
/1�
S�nch�ono�s
Mode 1
8-bit UART
Va�iable
As�nch�ono�s
Mode �
9-bit UART
SP0CLK/3� o�
SP0CLK/64
As�nch�ono�s
Mode 3
9-bit UART
Va�iable
As�nch�ono�s
Note that the SP0CLK is described in the UART0 Baud Rate Setup section.
Bit 5
SM20:
Multiprocessor communication enable control
0: Disable
1: Enable
Refer to the UART0 Multiprocessor Communication section for details.
Bit 4
REN0:
UART0 serial data reception enable control
0: Disable
1: Enable
Bit 3
TB80:
Ninth Transmit bit assignment
0: Low
1: High
This bit is only available in Mode 2 and Mode 3. It is not effective in Mode 0 and Mode
1. The bit is assigned using the application program.
Bit 2
RB80:
Ninth Receive bit assignment
0: Low
1: High
This bit is used to assign the level of the ninth bit in Mode 2 and Mode 3. In mode 1, if
the SM20 bit is zero, the RB80 bit is assigned as the level of the received stop bit. It is
not available in Mode 0.
Bit 1
TI0:
UART0 transmit interrupt flag
0: No interrupt request
1: Interrupt request
This bit must be cleared using the application program.
Bit 0
RI0:
UART0 receive interrupt flag
0: No interrupt request
1: Interrupt request
This bit must be cleared using the application program.