Neo_M660A GPRS Module Hardware User Guide
Copyright © Neoway Technology Co., Ltd
7
USB Interfaces
24
VBUS
AI
USB voltage test
27
USB_DP
DI/O
USB interface
differential data cable
Complying with
the USB1.1
standard
Used for
firmware
download
28
USB_DM
DI/O
Reserved Pins
5, 6,
11~14,
23,
34~38,
40~44,
47~51,
66~68
NC
Must be left
disconnected.
Cannot connect
to power supply
or ground.
P: indicates power supply pins
NC: indicates pins that are not supported and must not be connected
DI: indicates digital signal input pins
DO: indicates digital signal output pins
I/PD: indicates digital signal input pins with pull-down
I/PU: indicates digital signal input pins with pull-up
AI: indicates analogy signal input pins
AO: indicates analogy signal output pins
The maximum input voltage at all IO ports (including peak signal current) cannot exceed 3.1 V because
the module uses a 2.8 V IO power system. In the application of the module, the IO output voltage from the
3.3 V power supply system of the external circuit might greatly overshoot 3.1 V due to the signal integrity
design. In this situation, the IO pins of the module might be damaged if the IO signals are connected to the
IO port on the 2.8-V system. To rectify this issue, take measures to match the level. For details, see the 3.2
UART.