Smart Machine Smart Decision
SIM521x EVB User Guide
11.04.2011
19
4.8 USB interface
Figure 10: USB Interface
It is a normal 4Pin USB connector.
Table 14: USB interface
Pin
Signal
I/O
Description
1 USB_VBUS
I
5V
2 USB_DM
I/O
D+ line
3 USB_
DP
I/O
D- line
4 GND
Ground
4.9 Switch interface
Figure 11: Switch Interface
Table 15: Switch interface
Pin
Signal
I/O
Description
1 GPIO4
I
RF switch
：
ON : Normal mode
OFF : Flight mode
2
RS232 chip SHUTDOWN
I
UART switch
3 PWRER_ON
I
Power on the module
4 RESET
I
Reset the module
5 GPIO0
I
A key for interrupt
