LoRaProMini - A low power LoRaWAN Node

A LoRaWAN sensor node, based on ATmega328P MCU (Arduino Pro Mini) and RFM95W/SX1276 LoRa Transceiver.

The module can be used:

Collect various climate values with environmental sensors. See Environmental (Weather/Clima) Sensor

Tell if the letter carrier has put new letters in your mailbox. See Mailbox Monitor

Notify if someone rang the doorbell

Act a Wireless button

and many more...

Features

Deep sleep MCU and sensors between data transmissions

Two interrupt inputs could use to wake up the MCU and sensors from deep sleep

Confirmand und unconfirmed data up messages

Ultra low power consumption. Under 10μA with all features and sensors

Power input 3.5-6V:

Battery (Li-Ion or Li-SOCl2 works fine)

Battery with solar charger

Sensor support

Bosch BME280 (humidity, barometric pressure and ambient temperature)

Maxim DS18B20(+)/DS18S20(+)/DS1822 1-Wire temperature sensor

Warning

LoRaProMini does not take care of the compliance with the duty cycle limitation. Please select only transmission intervals that are within the legal limits (1%/0.1%). Please also note that the interrupt inputs may cause additional transmissions if this function is activated.

Example Applications

Environmental (Weather/Clima) Sensor

Download Radiation Shield STL

Buy Waterproof LED Solar Light

Mailbox Monitor

Download Case STL

Buy Normally Opened Reed Switches

More pics

The Things Stack configuration

LoRaWAN version MAC V1.0.3

How to use

Manufacture the PCB. Here you find the Gerber files

Assemble the PCB. Here you find the Bill of Materials (BOM)

Attention: The current version (v3.1) of the PCB has no ISP header! A pre-burned Atmega328P must be installed. I got one from an Arduino Pro Mini Board (3.3V 8 Mhz), because a completely assembled Arduino is cheaper than a single chip

Flash config firmware (See How to flash)

Start voltage calibration from menu

Start configuration builder Configuration Builder

Measure the voltage with a multimeter

Insert multimeter voltage and the analog value in the Volts-per-bit (VPB) calculator to get VPB factor.

If u have a adjustable power supply, try different voltages to find best factor. Warning: The maximum voltage is 6 Volt

Fill out the other fields like activation methode, session keys and EUIs

Write configuration to EEPROM using configuration menu

Check written configuration via configuration menu

Flash debug or release firmware (See How to flash)

Finish

How to flash

avrdude-F -v -c arduino -p atmega328p -P <COM PORT> -b 57600 -D -U flash:w:<FIRMWARE FILE>:i

Example:

avrdude -F -v -c arduino -p atmega328p -P COM4 -b 57600 -D -U flash:w:firmware_1.0_config.hex:i

Firmware Changelog

Version 2.7

Fixed a problem of resetting the interrupt trigger too early.

Version 2.6

Second attempt to solve the unnecessary delay due to the duty cycle limitation. Overflow of timer0 freezes the MCU after around 20 transmissions.

Version 2.5

Fixed problem with duty cycle limitation

Fixed MCU deepsleep inaccuracy

Version 2.4

An external interrupt during a transmission terminates the transmission and starts a new transmission.

Enabled Link Check Mode

Version 2.3

Fixed Typo

Version 2.2

An additional send delay between 0 and 20s has been added to avoid overlaps between different nodes with exactly the same send interval

Some flash memory optimizations

Version 2.1

Improved (debug) logging to serial output

BME sends -127°C (link DS18x) if no sensor was found

Version 2.0

Added wake up trough interrupt pins

Added option for disable interrupt pins

Added option for confirmed uplink

Changed LoRaWAN data up message

Added state of interrupt pins

Combined major and minor version byte into a single byte (4 bits for major and 4 bits for minor)

Version 1.1

Only for testing CI Pipeline

Version 1.0

Initial Version

PCB Changelog

Version 3.2

Fixed C7 (Replaced 10uF with 100nF)

Version 3.1

Added white field to specify the Node ID

Version 3.0

Removed Arduino Pro Mini Dauther PCB

Added ATMEGA328P direct to the PCB

Added pins for unused GPIOs

Added D2 and D3 with Pulldowns and connector as external interrupts (need FW v2.0 or higher)

Version 2.2

Added RST pin to connector for programming

Version 2.1

Added connector for programming

Version 2.0

Smaller PCB

Rounded Edges

Fixed issue with DS18x onboard pin mapping

Version 1.0

Initial PCB

TTS Payload Formatter (formerly TTN Payload Decoder)
function decodeUplink(input) {
  var bytes = input.bytes;

  var itrTrigger = (bytes[0] & 0x1) !== 0; // Message was triggered from interrupt (bit 0)
  var itr0 = (bytes[0] & 0x2) !== 0; // Interrupt 0 (bit 1)
  var itr1 = (bytes[0] & 0x4) !== 0; // Interrupt 1 (bit 2)
  var bat = (bytes[1] << 8) | bytes[2]; // Battery
  var fwversion = (bytes[3] >> 4) + "." + (bytes[3] & 0xf); // Firmware version
  var temp1 = (bytes[4] & 0x80 ? 0xffff << 16 : 0) | (bytes[4] << 8) | bytes[5]; // BME Temperature
  var humi1 = (bytes[6] << 8) | bytes[7]; // BME Humidity
  var press1 = (bytes[8] << 8) | bytes[9]; // BME Pressure
  var temp2 =
    (bytes[10] & 0x80 ? 0xffff << 16 : 0) | (bytes[10] << 8) | bytes[11]; // DS18x Temperature

  var mbStatus = "UNKNOWN";
  if (itr0) {
    mbStatus = "FULL";
  } else if (itr1) {
    mbStatus = "EMPTY";
  }

  return {
    data: {
      interrupts: {
        itr0: itr0,
        itr1: itr1,
        itrTrigger: itrTrigger,
      },
      extra: {
        mbStatus: mbStatus,
        mbChanged: itrTrigger,
      },
      fwversion: fwversion,
      bme: {
        temperature: temp1 / 100,
        humidity: humi1 / 100,
        pressure: press1,
      },
      ds18x: {
        temperature: temp2 / 100,
      },
      battery: bat / 100,
    },
    warnings: [],
    errors: [],
  };
}