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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
S1CON Register – UART1 Control register
SFR Address: 9Bh
Bit
7
6
5
4
3
2
1
0
Name
SM
—
SM�1
REN1
TB81
RB81
TI1
RI1
R/W
R/W
—
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
—
0
0
0
0
0
0
Bit 7
SM:
UART1 Operating mode select bit
0: Mode A
1: Mode B
The following table illustrates the corresponding mode descriptions and baud rates.
Operating mode details are described elsewhere.
SM bit
Mode
Mode Name
Baud Rate
Synchronisation
0
Mode A
9-bit UART
Va�iable
As�nch�ono�s
1
Mode B
8-bit UART
Va�iable
As�nch�ono�s
Bit 6
Unimplemented, read as “0”
Bit 5
SM21:
Multiprocessor communication enable control
0: Disable
1: Enable
Refer to the UART1 Multiprocessor Communication section for details.
Bit 4
REN1:
UART1 serial data reception enable control
0: Disable
1: Enable
Bit 3
TB81:
Ninth Transmit bit assignment
0: Low
1: High
This bit is only available in Mode A. It is not effective in Mode B. The bit is assigned
using the application program.
Bit 2
RB81:
Ninth Receive bit assignment
0: Low
1: High
This bit is used to assign the level of the ninth bit in Mode A. In mode A, if the SM21
bit is zero, the RB81 bit is assigned as the level of the received stop bit. It is not
available in Mode B.
Bit 1
TI1:
UART1 transmit interrupt flag
0: No interrupt request
1: Interrupt request
This bit must be cleared using the application program.
Bit 0
RI1:
UART1 receive interrupt flag
0: No interrupt request
1: Interrupt request
This bit must be cleared using the application program.