Functional Description

Overview

miro Insight Lux is a low cost, batteryless and fully configurable LoRaWAN® class A environmental Sensor.

The batteryless operation works by harvesting energy from ambient light sources to power the device using the onboard organic solar cell. Optionally, a version with a backup battery is also available.

The device features a temperature and a humidity sensor and optionally also a pressure and CO2 sensor. It reads out the sensors in a configurable interval and sends the data via LoRaWAN 1.0.3 either after each read out, or after accumulating a given amount of data.

Additionally, the miro Insight Lux is equipped with a hall-sensor (not available on all devices). Together with a magnet, it can be used to monitor doors or windows and send messages when they stay open for too long.

All settings, such as measurement time and accumulated data points, can be configured using LoRaWAN® downlink messages.

miro Insight Lux is available in a modern design high-quality plastic enclosure with different mounting options such as double-sided sticky tape or screw-on.

LoRaWAN keys

If you did not receive the LoRaWAN keys from Miromico AG directly, you should be able to retrieve them from our database. Please visit our DevEUI management docs page.

Power on

Upon initial delivery, the device will be powered off to save battery. To power it on, a small PCB pin has to be broken off. This will connect the battery to the processor, and the device should initialize all sensors and start to join.

Important

After the first power on (or a reset), the device will try to join. After joining, the sensors are immediately read out for the first time. The first uplink might, however, be delayed up to 10 minutes, due to the firmware and settings messages and duty cycling. This means that the second uplink might come sooner than the configured interval, but after that everything should run as expected.

Confirmed messages

If an uplink is sent as a confirmed message, the device expects an acknowledgment (ACK) from the LoRaWAN network. When no ACK is received, the miro Insight Lux will try to retransmit the message again, up to the configured number of retries (NbRetrans). If still no ACK is received, the measurements are discarded.

In the unlikely case that the accumulated data exceeds the maximum allowed payload size (LoRaWAN regulations), the oldest measurements will be discarded and lost. As many new data points as possible will be sent with the uplink. This scenario might happen if the data-rate is decreased during retries (see ADR ACK request).

Door Sensor

The on-board hall-sensor will detect if a magnet is nearby the device.

Note

The hall-sensor is not present on all devices.

The idea is that the sensor can be mounted to a door, so that a magnet will be next to it when the door is closed.

If no magnet can be detected for longer than the configured alarm time, an uplink will be sent. It contains an alarm counter, a door open counter and the currently set alarm time. If an alarm has been triggered and the door is closed again (i.e., the magnet is next to the device), another uplink with the same information is sent. If the door opens for less than the alarm time, the open counter is incremented, but no uplink is triggered. Every door status time, an uplink with the alarm, open counter and current door status is sent

Important

On the opposite side, there is also a Hall-sensor, but it is used to trigger a reset, when a magnet is close to it for more than 10 seconds!

Reset

Reset by hall sensor

In case the sensor shows faulty behavior or is transferred to a new LoRaWAN network server, it should be reset. For that purpose, a second hall-sensor is equipped. Holding a strong magnet close to the sensor for more than 10 seconds will trigger a reset and the device subsequently reinitializes sensors and tries to rejoin the network.

Reset by downlink message

To remotely reset the sensor device, a reset downlink command is implemented.

ADR ACK request

The ADR ACK request is a LoRaWAN feature to ensure that a device will stay connected to a network when ADR is enabled.

After 5 messages without any response from the network, the miro Insight Lux will ask the network to respond with the next uplink. If the network fails to answer for 2 uplinks, the device will lower its data-rate, to increase the chances of a message getting to the gateway. This continues, until either the network answers and the initial counter is reset, or 2 uplinks are sent with data-rate 0 (SF12). If the network still has not answered, the device will reset and try to join again. With default settings, a device will approximately reset itself after not hearing from the network in one day.

This feature is useful if a device is moved or connectivity changes. In the case that a device is reregistered in a different network, it will also try to join again on its own and no manual reset has to be performed.

LED Description

The onboard LED indicates the following states: - Flash Blue: LoRaWAN transmission - Flash Green: LoRaWAN reception or successful network join. - Flash Red: failed network join.

Onboard LED indications can be enabled/disabled through a LoRaWAN downlink message. Only the indications about the network join can't be disabled.

Known issues

There are no issues with the device currently known.