LoRaWAN Protocol

The Multiflexmeter communicates over LoRaWAN using OTAA (Over-The-Air Activation) on the EU868 frequency band.

Network Configuration

Parameter	Value
Activation	OTAA
Region	EU868
LoRaWAN Version	1.0.x
ADR	Enabled
Default TX Power	14 dBm

Uplink Messages

FPort 1: Measurement Data

General-purpose measurement results from the sensor module.

Format:

<Module Address> <Module Type> <Data Blob>

Field	Size	Description
Module Address	1 byte	I2C address (typically 0x36)
Module Type	1 byte	Sensor type identifier
Data Blob	Variable	Module-specific data

The data format depends on the sensor module. See Data Formats for specific module payloads.

FPort 2: Version Ping

Sent after successful join to report device identity.

Format:

0x10 <FW_HI> <FW_LO> <HW_HI> <HW_LO>

Byte	Description
0	Command byte (0x10)
1	Firmware version high byte
2	Firmware version low byte
3	Hardware version high byte
4	Hardware version low byte

Version Encoding (16-bit):

Bit 15:     Protocol (0=dev, 1=release)
Bits 14-10: Major version (0-31)
Bits 9-5:   Minor version (0-31)
Bits 4-0:   Patch version (0-31)

Example:

• Version v3.7.0 release = 0x8E00
  • Bit 15 = 1 (release)
  • Major = 3 → bits 14-10
  • Minor = 7 → bits 9-5
  • Patch = 0 → bits 4-0

FPort 3: RPM Data (Legacy)

Single-byte RPM measurement (0-255 range).

Note

FPort 3 is used for legacy RPM-only mode. Current firmware versions use FPort 1 with the sensor passthrough architecture.

Downlink Commands

All downlink commands can be sent on any FPort.

Set Measurement Interval (0x10)

Change the measurement and transmission interval.

Format:

0x10 <Interval_HI> <Interval_LO>

Byte	Description
0	Command byte (0x10)
1	Interval high byte
2	Interval low byte

Parameters:

• Interval: 16-bit big-endian value in seconds
• Minimum: 20 seconds
• Maximum: 4270 seconds (~71 minutes)

Example: Set interval to 300 seconds (5 minutes):

0x10 0x01 0x2C

Forward Module Command (0x11)

Send a command to an I2C sensor module.

Format:

0x11 <Address> <Command> [Parameters...]

Byte	Description
0	Command byte (0x11)
1	Module I2C address
2	Command to send
3+	Optional parameters

Example: Send command 0x05 to module at 0x36:

0x11 0x36 0x05

Set Wheel Teeth Count (0x12)

Configure the wheel teeth count for RPM calculation.

Format:

0x12 <Count>

Byte	Description
0	Command byte (0x12)
1	Teeth count (1-255)

Example: Set 91 teeth:

0x12 0x5B

Force Rejoin (0xDEAD)

Force the device to reset and rejoin the network.

Format:

0xDE 0xAD

The device will rejoin after approximately 5 seconds.

Use Sparingly

Force rejoin causes a network reset. Use only when necessary, as frequent rejoins consume airtime and network resources.

TTN Fair Use Policy

The firmware enforces TTN’s fair use policy:

• Maximum 30 seconds of airtime per day
• Automatic interval adjustment if exceeded
• Configurable via EEPROM (USE_TTN_FAIR_USE_POLICY)

Payload Formatter Example

TTN payload formatter (JavaScript) for FPort 1:

function decodeUplink(input) {
  var bytes = input.bytes;
  var port = input.fPort;

  if (port === 1 && bytes.length >= 3) {
    var moduleAddr = bytes[0];
    var moduleType = bytes[1];

    if (moduleType === 0x01) {
      // Poldermill sensor
      var flags = bytes[2];
      var revolutions = (bytes[3] << 24) | (bytes[4] << 16) |
                        (bytes[5] << 8) | bytes[6];
      return {
        data: {
          module_address: moduleAddr,
          module_type: moduleType,
          spinning: (flags & 0x01) !== 0,
          pumping: (flags & 0x02) !== 0,
          revolutions: revolutions
        }
      };
    }
  }

  return { data: {} };
}