Note:  Dev-Board: Can be used directly; Module: Only core function, need to cooperate with external PCB or circuit. Lithium: All lithium battery socket for Heltec boards is SH1.25-2; Vext: 3.3V(500mA) output, for external devices (e.g. sensors) power supply, in deep sleep mode, Vext can be shut down via software; Low Power: Products: low power design, of Whole Circuit, the measured data are the current of the system during deep sleep. Feature:  -Microprocessor: ESP32 (dual-core 32-bit MCU + ULP core + Internal 4MB FLASH), with LoRa node chip SX1276; -Micro USB interface with a complete voltage regulator, ESD protection, short circuit protection, RF shielding, and other protection measures; -Onboard SH1.25-2 battery interface, integrated lithium battery management system (charge and discharge management, overcharge protection, battery power detection, USB / battery power automatic switching); -Integrated WiFi, LoRa, Bluetooth three network connections, onboard Wi-Fi, Bluetooth dedicated 2.4GHz metal 3D antenna, reserved IPEX (U.FL) interface for LoRa; -Integrated CP2102 USB to serial port chip, convenient for program downloading, debugging information printing; -Support the Aduino development environment; -(Exclusive) Supports the Aduino version of the ESP32 + LoRaWAN protocol routine provided by Heltec. This is a standard LoRaWAN protocol that can communicate with any gateway/base station running the LoRaWAN protocol (requires serial number activation, only the development of the company) The board is available, the serial number can be queried on this page); -With good RF circuit design and good low-power design (sleep current ??? 30uA), it is convenient for IoT application vendors to quickly verify solution and deploy applications; Specification:  Source:  MCU: ESP32( 240MHz Tensilica LX6 dual-core + 1 ULP, 600 DMIPS, 520KB SRAM, Wi-Fi, dual mode Bluetooth).  LoRa chip: SX1276.  LoRa bands: EU_433, CN_470_510, EU_863_870, US_902_928 four bands optional.  LoRa maximum output power: 18dB/2dB.  Hardware resources: UART x 3; SPI x 2; I2C x 2; I2S x 1.  29 general GPIO.  Display: None.  FLASH: 4MB(32M-bits) SPI FLASH.  interface: Micro USB x 1; LoRa antenna interface(IPEX) x 1.  Size: 50.2 x 25.5 x 9.74 mm.  USB to UART Bridge: CP2102.  Battery Type: 3.7V Lithium(SH1.25 x 2).  Battery detection circuit:  External device power control (Vext):  Low power design: Deep Sleep 30uA.  Electrical characteristics: Condition/Minimum/Typical/Maximum Power Supply: USB powered(500mA)/4.7V/5V/6V.  Lithium powered(250mA): 3.3V/3.7V/4.2V.  3.3V(pin)powered(150mA): 2.7V/3.3V/3.5V.  5V(pin)powered(500mA): 4.7V/5V/6V.  Power consumption(mA): WIFI scan/115mA.     Package includes:  1 x Wireless ESP32 Stick Lite