Module ground wire

Module power supply positive reference, voltage range: 3.3～5.5V DC

Used to indicate the module's operating status; outputs a low level during the power-on self-test initialization period when the user wakes up the external MCU ; (can be left floating).

TTL serial port output, connected to the external RXD input pin;

TTL serial port input, connected to the external TXD output pin;

In conjunction with M0, it determines the module's four operating modes (it cannot be left floating; if not in use, it can be grounded).

In conjunction with M1, it determines the module's four operating modes (it cannot be left floating; if not in use, it can be grounded).

Antenna interface (high-frequency signal output, 50 ohm characteristic impedance)

Fixed

Fixed

Fixed

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The reset pin during program loading (floating, no user connection required).

Ground pin during program loading (floating, no user connection required).

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