I tested the RAK7204 environmental sensor. You can see the pictures from Borroz posts.
It is based on an BME680 sensor and can measure temperature, humidity, air pressure and gas resistance. It is ideal to monitor the air quality in a room.
The design is nice and clean and the case feels very stable. Also the size is well-choosen for a qualitative look.
A RAK811 LoRa module is used as controller for the application and communication to a LoRaWAN concentrator. On the PCB is also a micro USB port for updating bootloader and firmware. One big advantage about the RAK811 module is the usage for most common LoRa-frequencies in a single chip. It is possible to change the same sensor between 433MHz, 868MHz and 915MHz (and even more, just have a look at the datasheet).
About temperature, humidity and air pressure is nothing to comment. Standard values with given accuracy from the manufacturer. But there is more to say about the ‚air quality index‘ promised on RAKs website:
First of all we should be clear, the BME680 doesn‘t measure CO2. It is a sensor for VOCs (volatile organic compounds). But the amount of VOCs in the air, is also a comparative value for the air-quality. It will be represented by a so called ‚gas resistance‘.
When I got the sensor, I was only able to receive temperature, humidity and air pressure from the sensor. No air quality. After a few messages with an engineer from RAK he told me, that there are still troubles with the air quality index. You should know that Bosch (the sensor manufacturer) doesn‘t provide the formula for air quality index calculation directly. Instead they have some pre-compiled libraries for specific controllers.
Since the update from 2019-10-17, RAK7204 provides the raw value from the sensor, the gas resistance. It‘s better than nothing, but it‘s not the promised ‚air quality index‘, which can be a simple value for indication of good or bad air quality.
All in all the sensor is a good product for a fair price. The problem with the air quality index will be hopefully fixed with the next update.