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4.2.5 16550 & interrupt
VCC
VCC
VCC
VCC
DCD1
DSR1
RTS1
C1
.1u
C0805
J1
CON20A
JDIP20P
2
4
6
8
J2
CON20A
U1
16C550PT
TQFP48
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
D0
D1
D2
D3
D4
D5
D6
D7
DDIS
OUT1
OUT2
RTS
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
GND
GND
VCC=42
GND=18
TI_1
X
X
TXD1
RXD1
RXD1
The address 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 it
to another value. It is compatible with
COM3
of 7188XB/C & 7188E library.
7188E Series Hardware User’s Manual, 2004, v2.2, 7MH-016-22 ----- 48