Error code

[bill-orange]

I am getting this error code randomly between good readings. If it starts generating errors they keep coming. I am clock stretching on an ESP32 with a generic Chinese CS811 (ver. 2 firmware)

errstat=899=--vhXmrwF--AD-iE

How do I translate this? I can probably track this down on my own if I know what's going on. Interestingly, the first reading after setup is always good.

[maarten-pennings]

As you can see in the .h file
ERRSTAT is a merge of two hardware registers: ERROR_ID (bits 15-8) and STATUS (bits 7-0)

So, we have to split the hex value (899 or rather 0899) and the string (--vhXmrwF--AD-iE)
ERROR has hex value 08 which corresponds to --vhXmrw and
STATUS has hex value 99 which corresponds to F--AD-iE
Capitals mean bit-is-set, lowercase means bit-is-clear, dash means bit has no meaning.
See function CCS811::errstat_str for details

What does this mean?

Most part of STATUS is ok (see datasheet page 18 on ams.com/ccs811): The F tells that the firmware is in application mode (not bootmode) , the A means that the application image is valid (flashed correctly), D means there is new measurement data. But you also have an E - for Error. This should not happen.

When you have an E/error, the ERROR register gives details. You have X (datasheet page 24) meaning "The sensor resistance measurement has reached or exceeded the maximum range". I'm not sure what does means, maybe your sensor is broken. Is your supply voltage correct?

[bill-orange]

Supply voltage is correct. It is possible that my chip is bad. I ordered another for testing. Also, I am testing the strong possibility of WiFi interference between the ESP32 and the sensor. I have placed a small tantalum cap on the power supply and shielded the backside of the board. I have reduced Tx power on the ESP32 to 50%. No errors so far. I started down this path when I discovered that the errors we are discussing disappeared when I removed WiFi.begin() from the sketch. I don’t know that anyone else with CCS811 issues has tried this. Another possibility is that more power is available to the CCS811 when WIFI is off.

[mjsqu]

I am also seeing this issue with an AMS sensor (the one that comes with the USB evaluation kit). I have tried it with:

• Raspberry Pi
• Adafruit Huzzah Feather ESP8266
• Duinotech ESP32

I have got readings of eCO2 = 400ppm and eTVOC = 0ppb, but that is only if I use your library and ignore the errors that are received when getting ALG_RESULT_DATA, and the values never move from 400,0.

I get the 899 error as mentioned by @bill-orange, but the difference is I don't ever see any good readings.

When I use the CCS811 with the USB evaluation kit in Windows the sensor operates normally.

Thanks @maarten-pennings for your development of this library, it's the best one I've found which aligns with the programming and interfacing guide and reports the meanings of the errors back from the sensor! 👍

Going to attempt running with pull-up resistors on SDA, SCL later.

[bill-orange]

@mjsqu Please try running the sensor in your application but with WiFi turned off. Let’s see what happens. Comment out WIFi.begin(); in my case, pull-ups did not matter.

[mjsqu]

No change unfortunately, I never had WiFi.begin(); in my code. But I added WiFi.mode(WIFI_OFF); just to make sure and it still fails. Will be checking with another sensor once it arrives in the post.

[bill-orange]

For test purposes you might try the SparkFun library while you are waiting.

…

Sent from my iPhone

On May 27, 2019, at 12:32 PM, mjsqu ***@***.***> wrote: No change unfortunately, I never had WiFi.begin(); in my code. But I added WiFi.mode(WIFI_OFF); just to make sure and it still fails. Will be checking with another sensor once it arrives in the post. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or mute the thread.

[mjsqu]

Yep, I've tried that one and the Adafruit one!

[ngttai]

Hi, I am a newbie about ccs811
I download this library, update firmware for ccs811 and run example ccs811basic.
recently, I get an error code 1899 in terminal, I know it as CCS811_ERRSTAT_HEATER_FAULT and CCS811_ERRSTAT_MAX_RESISTANCE
I use platformIO and hardware is BluePill(stm32f103c8)

setup: Starting CCS811 basic demo
setup: ccs811 lib  version: 10
setup: hardware    version: 12
setup: bootloader  version: 1000
setup: application version: 2000
CCS811: waiting for (new) data
CCS811: errstat=1091=--vHxmrwF--Ad-iE
CCS811: errstat=1091=--vHxmrwF--Ad-iE
CCS811: errstat=1891=--vHXmrwF--Ad-iE
CCS811: errstat=1899=--vHXmrwF--AD-iE
CCS811: errstat=1899=--vHXmrwF--AD-iE
CCS811: errstat=1899=--vHXmrwF--AD-iE

[maarten-pennings]

Hmm - max resistance could be a symptom of heater fault.
And heater fault looks like defect hardware to me ... :-(

[mbilalyigit]

I have same only error CCS811_ERRSTAT_MAX_RESISTANCE.

I have two CCS811. Using the same code, one of them returns always (400,0). Even RAW data resistance value is 1023( 10 bit max value ). Did anyone solved this issue? Bill's solution didn't work for me.

Only way I am getting different value is blowing air to device. It decreases baseline value. And I can read some meaningful value with really bad resolution. But error is still there.

Note: Reading LSB first, makes baseline linear in my case.

[pilakito]

I have nearly same issue,

I set up the circuit for arduino nano as indicated. In addition i am using logic level converter TXS0108E.
Because, i see "The CCS811 datasheet specifies that logic high is at most 1.0 x VDD (i.e. 3v3), connecting the CCS811 to the I2C pins of the Nano (at 5V) is thus a risk for the CCS811." note.

When i started the arduino program, in serial terminal i see these.

setup: Starting CCS811 basic demo
setup: ccs811 lib version: 11
setup: hardware version: 12
setup: bootloader version: 1000
setup: application version: 1100
CCS811: errstat=0=--vhxmrwf--ad-ie

if errstat is 0 why my is my code running. If I didn't get it wrong, it shouldn't be an error.

I didn't edit the library or cs811basic code.

[bill-orange]

How is you CC811 getting power? Perhaps it is not getting enough current when it is trying to read.

[maarten-pennings]

Hi @pilakito, The level shifter makes sense. I assume you run the basic example, the output looks good. You get bootloader and application version, so nano and ccs are working, and the i2c communication too. So everything good

However, after the startup, things go wrong. The library should return CCS811_ERRSTAT_OK, which is the OR of the flags: CCS811_ERRSTAT_DATA_READY, CCS811_ERRSTAT_APP_VALID, and CCS811_ERRSTAT_FW_MODE .

# CCS811_ERRSTAT_DATA_READY          0x0008 // A new data sample is ready in ALG_RESULT_DATA
#define CCS811_ERRSTAT_APP_VALID           0x0010 // Valid application firmware loaded
#define CCS811_ERRSTAT_FW_MODE             0x0080 // Firmware is in application mode (not boot mode)

So, somehow, after getting versions, communication goes wrong.

Do you use the wakeup pin?

[pilakito]

Hello @maarten-pennings

I connected it to pin 13 with level shifter. I didn't connect directly.

@bill-orange It connected to my computer.

[maarten-pennings]

If you did not modify the library or examples, the begin() method also checks the status (eg see line 169 in cpp file) and it is not 0. So, I'm puzzled