Functional Description
Overview
miro Insight is a low cost, battery powered and fully configurable LoRaWAN® class A environmental Sensor.
The device features a temperature and a humidity sensor and optionally also a CO2 and VOC 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 accumulating1 a given amount of data.
Additionally, the miro Insight 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 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 a join, 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 will try to retransmit the message again, up to the configured number of tries (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!
VOC Sensor
The VOC sensor will measure the content of certain gases in the air and give an index for the current quality. This index does not represent any actual measurements; it only indicates how healthy the current air is to spend time in.
Note
The VOC sensor is not present on all devices.
| IAQ Index | Air Quality | Impact (long-term exposure) | Suggested action |
|---|---|---|---|
| 0-50 | Excellent | Pure air; best for well-being | No measures needed |
| 51-100 | Good | No irritation or impact on well-bein | No measures needed |
| 101-150 | Lightly polluted | Reduction of well-bein possible | Ventilation suggested |
| 151-200 | Moderately polluted | More significant irritation possible | Increase ventilation with clean air |
| 201-250 | Heavily polluted | Exposition might lead to effects like headache depending on type of VOCs | Optimize ventilation |
| 251-350 | Severely polluted | More sever health issue possible if harmful VOC present | Contamination should be identified if level is reached even w/o prescedence; maximize ventilation and reduce attendance |
| >351 | Extremely polluted | Headaches; additional neurotoxic effects possible | Contamination needs to be identified; avoid prescence in room and maximize ventilation |
It also comes with an accuracy level. Values below 3 should be taken into account. When starting the device for the first time, the sensor has to calibrate itself. It should be exposed to good and bad air during the first few hours of operations. A meeting room with a lot of people and occasional open windows should be perfect.
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 magnet close to it for more than 10 seconds will trigger a reset and subsequent reinit of the sensors and rejoin of the device.
Reset by downlink message
Tor remotely reset the sensor device, a reset downlink command is implemented.
ADR ACK request
Important
For US915 and AU915 regions, ADR is disabled, and the datarate is fixed to 3 (SF7), because otherwise the allowed payload size is too small for even single measurements for some sensor configurations.
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 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.
Important
As of 22.02.2021, there is a bug in the Loriot network server preventing this feature to work properly. If you experience daily resets, try to lower the ADR reactivity in Loriot (either in the device profile, or in the LoRaWAN parameters of the device directly)
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
-
Measurement data accumulation is not yet supported in the 2.4 GHz version of the sensor. ↩