DSB75 Development Support Board Rev. B1 Hardware Description
Confidential / Released
DSB75_hd_v12
Page 31 of 96
2008-08-26
3.5 RS-232
Interfaces
The DSB75 offers three asynchronous RS-232 interfaces:
•
COM1
(ASC0)
•
COM2
(ASC1)
•
COM3
(ASC2)
The status of all interface lines is indicated by LEDs (refer to section 4).
For using ASCx lines on the test pins X101, X102 without the DSB75 level converter please
disable receiver outputs by removing jumpers X204 and X206.
Figure 11 shows the simplified interface schematic. Figure 12 shows the placement of the D-
sub connectors, switches, jumper and the pin location. Electrical characteristics are specified
in section 8.
Figure 11: RS-232 interfaces
RXD0
TXD0
RTS0,DTR0
S200
S201
D200
IGT
PWR_IND
B2B
X100
1
3
1
3
200
200
200
200
4
1
2
4
1
1
CTS,DSR, DCD,
RING
RXD
TXD
RTS,DTR
9 pole D-sub
X201
8,6,1,9
2
3
7,4
GND
5
USC1
USC2
RS232
level converter
D201
200
200
200
2
2
TXD, RTS
TXD
9 pole D-sub
X202
GND
5
200
RXD
9 pole D-sub
X205
2
3
GND
3
1
1
3
3
1
1
3
3
1
3
1
RXD1, CTS1
RXD, CTS
TXD1, RTS1
2
2
RXD2_GPIO9
TXD2_GPIO10
S458
S459
S302,306
S303,307
S301,305
S300,304
2,8
3,7
5
RS232
level converter
V420
1
1
1
52,48,54,47
30
25
32
24
49,50
78
56
29,53
31,51
76
5
3V0
3V0
LED indication (0=on, 1=off)
d/dt
JP
X203
CTS0, DSR0,
DCD0, RING0
ASC_SD
JP
X204
PWR_IND
EN
SD
ASC_SD
JP
X206
PWR_IND
ASC_SD
V200
SD
EN
