User`s manual
5.2.5 16550 & interrupt
VCC
VCC
VCC
VCC
A0 A3
A1 D0 A4
A2 D1 A5
D2
D3
D4
D5 CS\
D6
D7
RESET
RD\
WR\ CLKOUTA ARDY
INT0 INT1
VCC RESET
RESET\
INT0 TO_1
14.7MHZ TI_0
SCLK DIO9
DIO4 DIO14
VCC VCC
A0 D0
A1 D1
A2 D2
A3 D3
A4 D4
A5 D5
A6 D6
D7
WR\
CS\ RD\
RTS1
DTR1
DCD1 DSR1
RTS1
RI1 CTS1
DSR1 DTR1 RI1
DCD1
CTS1
C1
.1u
C0805
J1
CON20A
JDIP20P
1
3
5
7
9
11
13
15
17
19
2
4
6
8
10
12
14
16
18
20
J2
CON20A
JDIP20P
1
3
5
7
9
11
13
15
17
19
2
4
6
8
10
12
14
16
18
20
U1
16C550PT
TQFP48
28
27
26
24
9
10
11
5
35
19
20
7
16
17
38
40
39
41
12
43
44
45
46
47
2
3
4
22
34
31
32
29
23
33
8
30
14
15
A0
A1
A2
ADS
CS0
CS1
CS2
RCLK
MR
RD1
RD2
SIN
WR1
WR2
CTS
DCD
DSR
RI
BAUDOUT
D0
D1
D2
D3
D4
D5
D6
D7
DDIS
OUT1
OUT2
RTS
RXRDY
TXRDY
DTR
SOUT
INTRPT
XIN
XOUT
U2
74LS138
1
2
3
6
4
5
15
14
13
12
11
10
9
7
A
B
C
G1
G2A
G2B
Y0
Y1
Y2
Y3
Y4
Y5
Y6
Y7
C3
.1u
C0805
C4
.1u
C0805
C5
.1u
C0805
C6
.1u
C0805
C7
.1u
C0805
U3
SP213EH
SSOP28
11
12
14
10
13
17
15
16
25
24
7
6
20
21
8
5
26
22
19
2
3
1
28
9
4
27
23
18
VCC
C1+
C1-
GND
V+
V-
C2+
C2-
SHDN
EN
T1IN
T2IN
T3IN
T4IN
R1OUT
R2OUT
R3OUT
R4OUT
R5OUT
T1OUT
T2OUT
T3OUT
T4OUT
R1IN
R2IN
R3IN
R4IN
R5IN
J3
CON10B
1
2
3
4
5
6
7
8
9
10
C8
.1u
C0805
GND
GNDGND
VCC=42
GND=18
TI_1
TO_0
X
X
X
TXD1
TXD1
RXD1
RXD1
The addressing space of 16550 is from BASE+0x10 to BASE+0x17 as follows:
Txbuf=BASE+0x10 /* tx buffer */
Rxbuf=BASE+0x10 /* rx buffer */
Dll=BASE+0x10 /* baud lsb */
Dlh=BASE+0x11 /* baud msb */
Ier=BASE+0x11 /* int enable register */
Fcr=BASE+0x12 /* FIFO control register */
Iir=BASE+0x12 /* Interrupt Identification Register */
Lcr=BASE+0x13 /* line control register */
Dfr=BASE+0x13 /* Data format register */
Mcr=BASE+0x14 /* modem control register */
Lsr=BASE+0x15 /* line status register */
Msr=BASE+0x16 /* modem status register */
Scr=BASE+0x17 /* Scratch register */
The power-up default value of BASE is 0.
It is not recommended to change the value of BASE from 0 to another value.
Note: it is compatible to COM3 of 7188XC/7188XB/7188E library.
I/O Expansion Bus for 7188X/7188E User’s Manual, Jun/2004 v1.4, 7PH-000-14---29