User's Manual

Page 20 of 31
2-14.
Table 2-14 U6100 LED control description
U6100 status indication by LED is listed in Table 2-15.
Table 2-15 LED display description
LED Status Description
Green Flicker quickly (100ms On/800ms Off) Networks searching
Flicker slowly(100ms On/3000ms Off) Registered in 3G networks
Flicker more quickly(100ms On/300ms Off) Working in 3G networks, and the data is transmitting
Always On Connected to 3G networks, but no data transmitting
Green + Red Flicker slowly(100ms On/3000ms Off) Registered in 2G networks
Flicker more quickly(100ms On/300ms Off) Working in 2G networks, and the data is transmitting
Always On Connected to 2G networks, but no data transmitting
Off Closed
Red Always On Error(No SIM card or failed in registering
networks )
2.2.9.2 Reference circuit
The reference circuit for LED is shown in Figure 2-12.
Figure 2-12 The reference circuit of LED control
1) The LED control pin（GPIO） controls the LED through a transistor, as is shown in Figure 2-12.
2) The reference value is 5mA. So the current-limiting resistor may be used. Just like the resistor R14 in Figure 2-12.
Pins of
board to board connector
SN. of 60Pin board to
board connector
Description
LED_CTL_G 58 The Green LED control
LED_CTL_R 60 The Red LED control