I‘m using ZMOD4410 and use algorithm iaq_2nd_gen. And when I place the sensor with a fixed concentration of alcohol gas, the TVOC value returned by the sensor is fluctuating.
The following picture is drawn by tvoc*1000.
So I'm asking if there is a register manual for the ZMOD4410 so that we can parse the tvoc values and see for ourselves.
Hello Nick,
Well as far as it concerns providing a register map file about ZMOD4410, let me inform you that we do not publish internal register details, because the ZMODs internal ASIC is very complex to configure. A misconfiguration will lead to an operation outside of our specification and may damage the sensor. So we recommend to use the already provided precompiled libraries depending the operation mode you use the sensor with.
Check the FAQ provided below:
https://en-support.renesas.com/knowledgeBase/20506419
In case for some reason you don't want to use the precompiled libraries we provide with your host MCU (eg limited memory) we also provide this module: https://www.renesas.com/en/products/sensor-products/environmental-sensors/metal-oxide-gas-sensors/rrh46410-firmware-configurable-air-quality-aq-module-embedded-artificial-intelligence-ai
Which is basically ZMOD4410 with internal Renesas MCU to run these algorithms and the user needs to communicate either with UART or I2C interface with RRH46410 to get the readings.
Regarding your issue, please let me inform you that since ZMOD4410 is a MOX sensor and provides the final VOC values depending the chemiresistor value of the MOX layer, which is changing depending the presence of VOCs gases; it is very important that you make sure that you stabilize properly the sensor especially if it is the very first time the sensor gets powered on.
On the very first power on we suggest to leave the sensor being working and measuring for at least 48 hours (and maybe more in some cases). And after this period elapses you should start evaluating the sensor measurements.
Also it is very important that in the beginning you leave the sensor in a "clean air" enviroment meaning a room with good air ventilation (open windows) and not so crowded. So that you give enough time to the sensor to calculate the baseline resistor which will be stored and used by the algorithm as the reference resistor value for clean air.
And in general we do not recommend powering off the sensor. For as much as possible the sensor stays powered on the better as far it concerns for the results it provides.
In case the sensor gets powered off after the very first stabilization (48 hours constantly working) the sensor will need at least 30 minutes to give good results. This time period of 30 minutes, typical start-up period gets less, if the sensor has been left working for as long as possible.
To compare the results of a custom device using ZMOD4410 we provide an EVK board:https://www.renesas.com/en/products/sensor-products/environmental-sensors/zmod4410-evk-indoor-air-quality-sensor-evaluation-kit
Which can be used with GUI SW tool to keep log files in .csv format. The sensors used on the daughter boards of the EVK to make sure that they are properly initialized. We make sure that they have been left working for 96 hours before leaving the factory.
Have you followed proper process for the sensor stabilization for the very first power-on?
Thanks and Regards,
IK