UB4B0 User Manua
l
22
No.
Signal
Type
Description
Note
5
VCC
Power
Supply Voltage
，
+3.3V
+5%/
–
3%
6
VCC
Power
Supply Voltage
，
+3.3V
+5%/
–
3%
7
Rx3 or Event2
Input
External Event 2 Default:
COM3 Receive Data
LVTTL
8
Event1
Input
External Event 1
LVTTL
9
ERROR
Output
Error Detected LED
LVTTL
，
Low Level
effective
10
Satellite LED
Output
Satellite LED
LVTTL
，
Low Level
effective
11
CTS2
Input
COM2
Clear to Send
LVTTL
12
RESETIN
Input
Hardware reset
LVTTL, Low Level
effective,
duration >20us
13
RTS2
Output
COM2 Request to Send
LVTTL
14
RxD2
Input
COM2 Receive data
LVTTL
15
CTS1
Input
COM1
Clear to Send
RS-232
16
TxD2
Output
COM2 transmit data
LVTTL
17
RTS1
Output
COM1
Request to Send
RS-232
18
RxD1
Input
COM1
receive data
RS-232
19
TxD3 or GPIO0
Input / Output General Purpose I/O
Default: COM3 Transmit
Data
LVTTL
20
TxD1
Output
COM1 transmit data
RS-232
21
USB D (-)
Input/Output
USB D -
