Quectel EC21 Series User Manual

LTE Standard Module Series
EC21_Series_Hardware_Design
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3.10. USB Interface
EC21 series contains one integrated Universal Serial Bus (USB) interface which complies with the USB
2.0 specification and supports high-speed (480 Mbps) and full-speed (12 Mbps) modes. The USB
interface can only serve as a slave device.
EC21 series module can be used for AT command communication, data transmission, GNSS NMEA
sentences output, software debugging, firmware upgrade and voice over USB.
The following table shows the pin definition of USB interface.
Table 11: Pin Description of USB Interface
Pin Name Pin No. I/O Description Comment
USB_DP 69 AIO USB differential data (+)
USB 2.0 Compliant.
Require differential impedance of 90 Ω.
If unused, keep them open.
USB_DM 70 AIO USB differential data (-)
USB_VBUS 71 DI USB connection detect Typical 5.0 V
GND 72 - Ground -
For more details about the USB 2.0 specifications, visit http://www.usb.org/home.
The USB interface is recommended to be reserved for firmware upgrade in customers’ designs. The
following figure shows a reference circuit of USB interface.
Figure 19: Reference Circuit of USB Application

Quectel EC21 Series Specifications

General

Brand	Quectel
Model	EC21 Series
Category	Control Unit
Language	English