Thermistor resistance on Sparkfun CCS811 Air Quality Breakout board

Sensors Environmental
1

I’ve soldered in the 10K thermistor (SEN-00250) to the NTC holes in the CCS811 breakout, in an attempt to get the board to read ambient temperature. I am now running the example script given in the CCS811 library (Example3_ThermistorCompensation), with all of the hardware connections correct, as far as I can tell:

3.3V to 3.3V pin
GND to GND pin
SDA to A4
SCL to A5
SEN-00250 (NTCLE100E3103JB0) between NTC terminals

I upload the script to the board, and get the following:

Apply NTC data to CCS811 for compensation.
CCS811 begin exited with: SUCCESS
CCS811 data:
 CO2 concentration : 400 ppm
 TVOC concentration : 0 ppb
 Measured resistance : 0.00 ohms
 Converted temperature : -273.15 deg C

Error: ReadRegInvalid

This error comes from the function, printSensorError(), defined in the same script, and specifies:

if (error & 1 << 1) Serial.print("ReadRegInvalid");

However, that’s as far as I can get, since I don’t know how to troubleshoot that error code. Please advise, if at all possible! Gracias.

2

Hi invertdna,

It sounds like that error is printing because there is no data from the thermistor you have soldered to the NTC pads. Can you take a couple of photos of your soldering and attach them to your reply? My guess is it is a connection issue.

3

It’s true… I’m not excellent with a soldering iron. But I’m improving!

I figured it might be a connection issue, so I tried three different thermistors. This led to some amount of solder hanging out on the board, making it difficult to get a nice placement of the thermistor, but it seems solidly in there…

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4

Your solder joints for the thermister look like they could use a little bit of work. I’d recommend reheating those and applying some fresh solder then cleaning the pads off with a q-tip that has some rubbing alcohol on it. Be very careful to not get any alcohol on the IC on the other side of the board as that can damage the sensor.

5

I have exactly the same problem. I don’t think the soldering is the problem in my case. I have already tried working with earlier versions of the library, but not luck. Same happens if I use another pair of CCS811 and ntc thermistor.

Hardware Connections (Breakoutboard to Arduino):
  3.3V to 3.3V pin
  GND to GND pin
  SDA to A4
  SCL to A5
  SEN-00250 (NTCLE100E3103JB0) between NTC terminals

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https://i.imgur.com/yVWePdp.jpg

https://i.imgur.com/lDaxZ11.jpg

6

Hi spez_fila,

I was able to recreate the issue here with a known good CCS811 Breakout and Thermistor so I believe there may be something in the library causing the problem. I am not sure yet what it is but we’re going to look into it. I believe that you filed [this issue so that will ping our Engineers about it as well. Hopefully, we’ll identify the cause of the problem and get a fix out soon.](readNTC() error · Issue #18 · sparkfun/SparkFun_CCS811_Arduino_Library · GitHub)

7

Hi TS-Mark,

thanks for checking it out. Yes I filed that issue, hope to get any updates soon.