User's Manual

LTE Module
EC20 Hardware Design
EC20_Hardware_Design Confidential / Released 36 / 83
3.10. USB Interface
EC20 contains one integrated Universal Serial Bus (USB) transceiver which complies with the USB 2.0
specification and supports high-speed (480Mbps) and full-speed (12Mbps) mode. The USB interface is
used for AT command, data transmission, GNSS NMEA sentences output, software debug and firmware
upgrade. The following table shows the pin definition of USB interface.
Table 10: USB Pin Description
Pin Name
Pin No.
I/O
Description
Comment
USB_DP
69
IO
USB differential data bus (positive).
Require differential
impedance of 90Ω.
USB_DM
70
IO
USB differential data bus (minus).
Require differential
impedance of 90Ω.
USB_VBUS
71
PI
Used for detecting the USB
connection.
3.0~5.25V
Typical 5.0V
GND
72
Ground
More details about the USB 2.0 specifications, please visit http://www.usb.org/home.
The USB interface is recommended to be reserved for firmware upgrade in your design. The following
figure shows the recommended test points.
Module
USB_DM
USB_DP
VBAT_BB
USB_VBUS
PWRKEY
GND
VBAT_RF
USB_DM
USB_DP
VBAT
USB_VBUS
PWRKEY
GND
Connector
ESD Array
GND
Figure 19: Test Points for Firmware Upgrade