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2.1.5.2
Serial port (COM1, 2)
The IT8673 incorporates the two 16C550 compatible serial port controllers (UART1 and UART2).
The 24MHz signal (fixed) is 13-frequency-divided into 1.8462MHz that is then used to produce a Baud rate clock. This port
operates in an asynchronous mode.
The two controllers are independent of each other. By setting up a configuration port with software, address and interrupt
assignment can be carried out.
The basic setting for this system is as specified below.
IT8673F
UART1
UART2
I T 8 6 7 3 F
TXD1
DTR1
RTS1
RXD1
DSR1
CT S1
DCD1
R I 1
TXD2
DTR2
RTS 2
RXD2
DSR2
CTS 2
DCD2
R I 2
RE S E T DRV
System
COM1
COM2
49
5 3
51
48
50
52
55
5 4
5 9
63
6 1
5 8
6 0
6 2
5 7
56
I/O address
3F8h-3FFh
OUT
A DM2 1 1
MA X 2 1 1
7
2
T1OUT
T1IN
6
3
T2IN
T2OUT
2 0
1
T3IN
T3OUT
2 1
2 8
T4IN
T4OUT
8
9
R1OUT
R1IN
5
4
R2IN
R2OUT
2 6
2 7
R3OUT
R3IN
2 2
2 3
R4OUT
R4IN
1 9
1 8
R5IN
R5OUT
2 4
2 5
SHDN
EN
A DM2 1 1
MA X 2 1 1
7
2
T1OUT
T1IN
3
6
T2IN
T2OUT
1
2 0
T3IN
T3OUT
2 1
28
T4IN
T4OUT
8
9
R1OUT
R1IN
5
4
R2IN
R2OUT
2 6
27
R3IN
R3OUT
2 2
23
R4OUT
R4IN
18
1 9
R5OUT
R5IN
2 4
2 5
SHDN
EN
2-18
Interrupt level
IRQ4
IRQ3
COM1 T X D
3 A
L
COM1 DT R
L
4 A
COM1 RT S
L
7 A
L
2 A
COM1 RX D
L
COM1 DS R
6 A
L
8 A
COM1 CT S
COM1 CD
L
1 A
L
COM1 R I
9 A
COM1 GND
5 A
COM2 T X D
3B
L
L
4B
COM2 DT R
COM2 RT S
L
7 B
L
2B
COM2 RX D
COM2 DS R
L
6B
L
8 B
COM2 CT S
COM2 CD
L
1B
L
COM2 RI
9 B
COM2 GND
5 B
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