VL6180X defaulting to error 0x02 (VCSEL Watchdog Test ) after 60 seconds

[andrew_henseleit]

I have the VL6180X doing continuous range measuring, which is working awesome, but after 60 seconds or so of the same reading I get an error in register 0x004D for VCSEL Watchdog Test. It says to replace the part, but I have had this with multiple Satel boards now. What could be the ACTUAL cause for this?

[John E KVAM]

It is very unlikely (near impossible) that you would get the same reading for 60 seconds. Each range will vary a mm or two, even in the best conditions.

My guess is your device rebooted.

Our XSHUT line is sensitive to noise. A big cap on the line seems to help.

But if you are really getting this error, we want to see the part.

Please contact me at:

john.kvam@st.com

[andrew_henseleit]

At the suggestion of our FAE we added a pull up resistor to the XSHUT line (even though it was disabled via code) and the problems have stopped. We were using the SATEL boards which make this almost impossible to achieve so we had to switch eval boards altogether. Andrew Henseleit | Senior Software Design Engineer BraunAbility 631 W. 11th St. Winamac, IN 46996 800.946.7513 ext. 3313 | andrew.henseleit@braunability.com www.braunability.com<> | AbilityVoice Blog<> | Faceboo<>k<> | YouTube<> [BraunAbility logo_EMAIL SIGNATURE SIZE]

[John E KVAM]

​So now we have 3 solutions to the noisy XSHUT line on the VL6180.

1. A larger cap on the XSHUT line near the sensor.
2. A good sized pull-up on the XSHUT line.
3. Changing the MCU's GPIO to in input to reduce noise. (Theory being you can change it back to an output if you really want to reset the chip.)

All three have been shown to work in various designs.