New MICS4514 integration question

Just seen this show up, that looks like a nice thing to have!
I can find the part available at Aliexpress, both a 4514 and a 5524. The 5524 is cheaper, would anyone know if that is also supported?

Anyway, the 4514 at aliexpress (no links, it shows right up if you search for MICS 4514) has five pins, two power of course, and then RED, NOX, PRE.
No idea what those pins are.

Does anyone know how such a board could be connected?


I accidently purchased that sensor from Aliexpress before I realized this wasn’t the sensor linked to on MiCS 4514 Gas Sensor — ESPHome. That sensor uses I²C Bus, but this MICS-4514 from Ali doesn’t have clock or data pins. Also, MICS-4514 is the model of the chip that the sensor board uses; spec sheet here for the chip:

The best info I found for this sensor was this YouTube video Arduino: MiCS-6814 [Sensore qualità aria] - YouTube In his sketch, it looks like the 3 pins are analog and in the video they are mapped as CO, NH3, and NO2.

From the diagram in the video, the sensor is mirrored, but if the pins are in the correct order, it would translate as follows:
PRE - CO (Carbon monoxide)
NOX - NH3 (Ammonia)
RED - NO2 (Nitrogen dioxide)

The AliExpress pages says it can detect the following, so not sure how to get all the other values:
Carbon monoxide CO 1-1000ppm
Nitrogen Dioxide NO2 0.05-10ppm
Ethanol C2H5OH 10-500ppm
Hydrogen H1 1-1000ppm
Ammonia nh3-500ppm
Methane CH4> 1000ppm
Propane C3H8> 1000ppm
Isobutane C4H10> 1000ppm

I’ll have to try this soon, but thinking I can get values using the 1 ADC pin on a esp8266 or can use all 3 analog pins if I use a esp32. I think these are serial and I’d need to use Analog To Digital Sensor in ESPhome to pull these values… Analog To Digital Sensor — ESPHome

Please let me know if anyone has any more insight on this. Thanks. This is the sensor I purchased:

I made the same mistake, just sort of expecting an SDA/SCL pin on the sensor. It would appear the PCBs are the reference circuits given by the manufacturer, as seen here:

As such, the PRE pin is connected to the FET and is for preheating the sensor. NOX and RED are the outputs for the NOx and CO sensors respectively. The sensors do measure the gases you described, but not independently.

The resistance of the RED sensor for instance would be between 0.6 and 0.5 if it measures H2S at a concentration of 0.1 to 0.5 ppm, or if it measures ammonia between 4 and 9 ppm. The problem being that you cannot distinguish between either of them.

To properly measure the sensor using this device, you’d need two ADCs and then calculate the output for each gas based on their resistances.

Seeing as I ordered the stupid thing anyway, I might try making an esphome integration myself. But I hope this information helps either way.

@dirrgang have you managed to do this integration? I too bought this sensor by mistake :face_with_spiral_eyes: