Radon Meter Dead

I killed it. I suspect as part of the delidding process it’s now dead. The sensor always returns 99.90pCi/L when I query it and the official board just displays “Err.” for a reading (same as it shows when over-range). Sanity checking with my other sensor shows that radon levels were not over range, it’s broken. Likely the sensor itself was mechanically stressed as I cut the solder joints holding the metal lid on. [Read More]

Radon Meter Screaming Capacitors

I believe I have finally corrected the intermittent crashing problem I was experiencing with the radon meter and have moved on to actually developing features for the board. Unfortunately, when testing graphing it seems I am working the micocontroller harder than I have previously done and it is becoming apparent that the ceramic capacitors are making a terrible noise. I’ve read you can hot glue them to reduce the noise however they are situated right beside a LDO that can reach temperatures as high as 60-70 degrees Celsius under certain situations and I’m not sure if that makes hot glue a better or worse option because of this. [Read More]

Radon Meter Crashing Found

After the previous changes I had yet another hang after just 40,800 seconds. Clearly it wasn’t the resistors or power filtering. Reading over my code again I noticed a hold-out from a code sample I copied about a year back when first doing some testing. It was “old” code and had been shared on the internet as an example, it couldn’t possibly be my problem… or could it? Here’s the relevant section: [Read More]

Radon Meter Power Test

So it wasn’t the pullup resistors. At about the 36 hour mark it restarted on it’s own (presumably the WDT caught a problem) then another 40,000 seconds later it hung. Interestingly enough the inter-frame time shows only 17ms right before it crashed, meaning the previous frame took 13ms to render. That seems slow and I wonder if the long frame times are somehow related. For now I’ve upped the on-board 12V capacitor from 47uF to 680uF, and added a 47uF electrolytic capacitor in parallel with the 2. [Read More]

Radon Meter Hangs Randomly

The radon meter replacement board I have been working on is experiencing an intermittent problem where it seems to lock up and stop responding. I have taken many guesses at where the problem may lie in my code but finally I caved and asked for help on the esp8266 subreddit. There I received 2 suggestions for why the radon meter is crashing and not recovering. The first suggestion was that the power may be browning out, and the second is that my I2C bus pullup resistors are not in range. [Read More]

Radon Meter Delidded

I finally got up the courage to de-lid the sensor itself.
The tiny blinking green LED that I could just barely discern through a tiny gap had been calling to me for a very long time and I could no longer resist.

Pictures follow:

[Read More]