Specifications

• Power input: DC5V or received by a lithium battery input VBAT and GND.
• Supports MCU level: 5V / 3.3V for TTL logic.
• (Such as the common 51 and for Arduino is 5v, STM32 is the 3.3v)
• Antenna use: IPEX antenna interfaces, you can use the version PCB antenna or antenna IPEX-SMA- peppers.

Pin Description

• 5V: power supply pin, the only input DC5V, used to power the board.
• V_TTL: access control board microcontroller core target voltage of 5V / 3.3V (according to its own microcontroller is much to distinguish kernel v), this pin is used to convert the GSM module board TXD and RXD for the corresponding TTL logic. ND: power supply ground
• TXD: send pin serial port module, TTL level (not directly connected to RS232 level)
• RXD: receive pin serial port module, TTL level (not directly connected to RS232 level)
• DTR: Data Terminal Ready
• SPKP: Core Audio output pin
• SPKN: Core Audio output pin
• MICN: Core Audio input
• MICP: Core Audio input
• RI: Ring core pin tips
• VRTC: RTC pin external battery.
• GND: power supply ground
• PWR: This pin can turn down or turn off the module.
• GND: power supply ground
• VBAT: lithium battery input pin, 3.3v-4.4v