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SIM7000C NB-IoT/LTE/GPRS Communication Board

Reference

This document is a reference guide for using the SIM7000C module and BME280 sensor library with Arduino boards. It explains core communication protocols including SoftwareSerial, AT commands and I2C, and also introduces a variety of API functions that facilitate the efficient development of IoT projects. The paper also elaborates on the core principles of NB-IoT technology and the technical specifications of the SIM7000C module, and illustrates the application of the BME280 sensor in measuring temperature, humidity and atmospheric pressure.

Library

Communication Protocol Description

  • SoftwareSerial: Used for communication between Arduino and SIM7000. Default pins: TX > D8, RX > D7. Baud rate: 19200 (reset from default 115200 to avoid garbled text).
  • AT Commands: Used to control the SIM7000. Commands must end with CR&LF. AT command list
  • I2C: Used for communication with the BME280 sensor. Default address: 0x76.

API Description

  • SIM7000 Library Functions:
    • begin(Stream &s_): Set software serial port.
    • turnON(): Turn ON SIM7000 in software. Returns true if successful.
    • turnOFF(): Turn OFF SIM7000 in software.
    • setBaudRate(int rate): Set baud rate of software serial port. Returns true if successful.
    • checkSIMStatus(): Initialize AT commands. Returns true if successful.
    • setNet(Net net): Set network mode (GPRS/GPRS-NB/NB-IOT). Returns true if successful.
    • checkSignalQuality(): Check signal strength (0-30; 99 = no signal).
    • attacthService(): Start connection service. Returns true if successful.
    • connect(Protocol ptl, const char *host, int port): Connect to network using TCP/UDP. Returns true if successful.
    • send(const char *str) / send(void* buf, size_t len): Send data over TCP/UDP.
    • recv(char* buf, int maxlen, int timeout): Receive data from server. Returns number of characters received.
    • close(): Disconnect from network. Returns true if successful.
    • initPos(): Initialize positioning function. Returns true if successful.
    • getPosition(): Get current position. Returns true if successful.
    • getLongitude(): Get longitude (east = positive, west = negative).
    • getLatitude(): Get latitude (north = positive, south = negative).
  • BME280 Library Functions:
    • begin(): Initialize BME280 sensor. Returns true if successful.
    • temperatureValue(): Get temperature in °C.
    • pressureValue(): Get pressure in Pa.
    • humidityValue(): Get humidity in %RH.
    • altitudeValue(float seaLevelPressure): Get approximate altitude in m (requires sea level pressure).

Principle

  • NB-IoT Technology: Narrow Band-Internet of Things, a low-power wide-area network (LPWAN) technology operating in authorized spectrum. Supports deployment on GSM, UMTS, LTE networks with 180KHz bandwidth.
  • SIM7000C Module: Based on SIMCom SIM7000C chip, supports multi-frequency LTE-FDD, dual-frequency GPRS/EDGE, NB-IoT, and onboard GNSS (GPS, GLONASS, Galileo, QZSS, BeiDou).
  • BME280 Sensor: Measures temperature, humidity, and pressure using I2C communication.

Other Supplementary Information

  • Board Overview:
    SIM7000C Arduino NB-IoTLTEGPRS expansion shield
  • Compatibility Test:
    MCU Pass Failed Not Tested Remark
    Arduino Uno √
    Arduino Leonardo √
    Arduino Mega1280 √ Connect D8 to D10
    Arduino Mega2560 √ Connect D8 to D10

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