1

GND

Ground

Module ground wire

2

NC

-

This pin needs to be left floating (for future expansion)

3

NC

-

This pin needs to be left floating (for future expansion)

4

NC

-

This pin needs to be left floating (for future expansion)

5

NRST

Input

Module reset pin, low level reset

6

NC

-

This pin must remain unconnected (for future expansion)

7

NC

-

This pin needs to be left floating (the SWCLK pin is recommended to be brought out if possible, for easier future maintenance or firmware customization).

8

GND

Ground

Module ground wire

9

NC

-

This pin needs to be left floating (for programming pin SWDIO, it is recommended to bring it out if possible, for easier future maintenance or firmware customization).

10

GND

Ground

Module ground wire

11

VCC

-

Module power source positive reference.

Voltage range: 2.5V ~ 5.5V DC

12

AUX

Output

Used to indicate the module operation status, when user wakes up the external MCU,it outputs low level during initialization after power on and self-check, can be configured as open-drain output or push-pull output, please refer to Parameter Configuration.

(can be floated)

13

TXD

Output

TTL serial input, connected to external TXD output pin. Can be configured as open-drain or pull-up input, please refer to Parameter Configuration.

14

RXD

Output

TTL serial input, connected to external RXD output pin;

It can be configured as drain open circuit or pull-up input. See parameter setting for details

15

M1

Input

The combination of M2, M1, and M0 determines the module's eight working modes.

16

M0

Input

The combination of M2, M1, and M0 determines the module's eight working modes.

17

M2

Input

The combination of M2, M1, and M0 determines the module's eight working modes.

18

GND

Ground

Module ground wire

19

ANT

-

Antenna interface (50 Ω characteristic impedance)

20

GND

Ground

Module ground wire

21

GND

Ground

Module ground wire

22

GND

Ground

Module ground wire