Saturday, March 28, 2020

ESP32 probe ongoing programming

After some digging around, I decided to change the ESP32 probe's protocol to TCP rather than UDP, at least for this initial stage, to ensure that we got a reliable stream of messages, and any unreliability would be more correlated with something in the probe itself. As usual, check out our code in the airball_probe_es32 directory in our repo.

The innards of the probe are now on a piece of plywood, and they look like the below. Given that what you see is all we need, this should all be quite easy to integrate into the 1-inch diameter new probe form factor.

The Wi-Fi RF performance seems excellent. I put this stuff all the way across my yard and behind the house, covered with a large metal garden dustpan, and I still got really good quality reception from my computer's Wi-Fi. That's very encouraging.

In other good news, if the battery monitor is to be believed, we draw about 170 mA when operating normally. With a 3400 mAH battery, that's about 20 hours of life. If we de-rate this to protect the battery, we still can expect a safe 12 hour battery life, which is my metric for, basically, "all day long". This means that a pilot or CFI can plop the probe onto their plane in the morning, fly around without paying any attention to it, and pull it out and put it on the charger in the evening.

Less encouraging is that, for some reason, I now seem to be having power supply issues, which cause flakey performance of the sensors and the Wi-Fi. Now it worked previously just fine, so I assume my wiring is crappy or I need decoupling caps, or some combination. But in any case, before we call the circuit done, I need to make sure these gremlins are no longer there, and learn what mitigations, if any, I need.

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