Support for CDM7160 / Figaro

[Vaikis]

Done.

[Vaikis]

Got sensor and some 30min time to play, tips for connection for other guys:
1. Used pull-up resistors 1K for both SCL (CDM7160 PIN 10) and SDA (CDM7160 PIN9)
2. CDM7160 PIN1 - VDD +5V, CDM7160 PIN2 GND
3. Dont forget to enable I2C as default mode is UART, CDM7160 MSEL (PIN6) connect to GND.
Module default I2C address is 0X69
For testing used this https://github.com/junichikatsu/CDM7160

[_petronie_]

Hi,
are you able compare output against MH-Z19? P.

[Vaikis]

Dont have MH-Z19 to compare....

[vlast3k]

Hi guys,

i have developed this library and spent a considerable time of my life fighting with the sensor
for some reason it was pain in the ass to make it work over I2C
since then Figaro released a second version with improved firmware, that may be work better.

in general it is a nice and small and energy efficient CO2 Sensor.
Sadly for some reason when connected to ESP8266 or maybe not only this it suffers BADLY from EMI
this thread describes my quest in dealing with it http://forum.vair-monitor.com/showthrea ... hlight=emi
i ended up having to wrap the sensor with copper or aluminium foil and then connecting it to ground... this sort of solved the issues

yet just a couple of days ago some customer notified me that his 5 devices employing the CDM7160 were giving results less than 200 PPM.. i've contacted Figaro yesterday.. let's see their response...

as for I2C, the protocol they have does not have any kind of CRC, so it is impossible to know if the data you get is correct or wrong.
i had to use 1k pullups (STRONG) to reduce the wrong data to some useable ampount

and then again i had to fiddle quite a lot with I2C communication and delays and retries to extract more useable data

Of course there may be some fundamental knowledge bit that i was missing - it was the first time i was writing a i2c library, but in any case doing it the simple and straightforward way wasn't that easy

i also plan to some day integrate what i did with ESPEasy, just that my priorities changed considerably in the last year, so now i have absolutely no time to spend on this.

as for price, the sensor is expensive, i had to buy in lots of 50-100 to get prices around 35 eur... adding the copper foil costed me some bucks more (As i got tired doing this myself at some point of time)

there is another company - Cubic, that offers calibration free sensors CM1108 and autocalibrating - CM1106, yet at least an year ago they were also not available in retail so i had to buy in lots of 50/100, pay 3$ delivery per sensor and then import fees to EU

There may be others as well that offer cheap sensors (e.g. compred to CO2 Sensor ) but i haven't monitored the market since one year

[Vaikis]

Found more details here
http://siva.cc.hirosaki-u.ac.jp/fuzoku/ ... nitor.html
also .ino file for this
http://siva.cc.hirosaki-u.ac.jp/fuzoku/ ... itor1e.ino
Seems it uses busy pin to ''capture" sensor state.

[_petronie_]

Hi,
there should be available version in playground repository quite soon. P.

[_petronie_]

Hi,
any idea why such different results are obtained? There are two sensors (CMD7160, MH-Z19) placed near each other but result seems to be shifted . P.

figaroVSmhz19.JPG (108.93 KiB) Viewed 17190 times

[grovkillen]

Hi,
any idea why such different results are obtained? There are two sensors (CMD7160, MH-Z19) placed near each other but result seems to be shifted . P.

figaroVSmhz19.JPG

Is the mh-z19 the line below (white) ? The sensor is on a 24h ABC cycle and will set the lowest point during that 24h period as 400ppm. They are supposed to be used in offices which will have the air purged during night, if you use them at home that will not happen and the sensor will start to drift...

[TD-er]

The MHz19 looks like a correct 400 ppm setpoint, since there are no 'flatliners', where the value is stuck at 400 ppm.
the values reported by the Figaro however are a bit to be worried about.
If they are correct, then you definitely should do more ventilation.
Above 700 ppm, it will start to smell like "can someone open a window please?"

[_petronie_]

Hi,
There is visible significant issue with MHZ19 which seems to be caused by some autocalibration. There is visible drop in the output values with no reason. Both sensors are place next to each other. Figaro sensor require extra shielding again EMI! P.

[TD-er]

That's the ABC feature.
It corrects the 400 ppm level, based on the lowest measured concentration of the last 24h.

So now you know why I added the option to disable this feature, since one day with less than optimal ventilation and the recorded values have quite some offset.

[denish]

hi,
i am try to interface CDM7160 sensor with LPC1768,but sensor was not respond.
any one pls help.