[Lab] ESP8266 Issues (and data logger)

[Adrian Jones]

Many thanks to Ken and Chris for excellent suggestions and ideas. What a
great community!

I expect the water level measurement range to be in the order of about 4-5'.
When considering sensors, this range seems consistent with the range and
resolution I've obtained from ultrasonic transducers in the past. The liquid
level sensor looks very interesting but limited in range. I love the idea of
the ping-pong ball. As for power consumption, I expect it to be quite low as
the device is asleep for most of the time - I'm thinking to an external
circuit for the timer (32KHz crystal and counter) for the sleep timer
triggering a FET in the supply line to the Arduino and transducer. Once the
software has executed the necessary steps, it would force the timer to
sleep. The solar charge controller also seems a good idea. I have a LiPo
battery from my helicopter that may do the trick. My initial idea was a
simple buck converter fed by the solar panel with a diode and current
limiting resistor connected directly into the LiPo.

Bye the way, I hope to have my ESP8266 data logger running by the weekend.
The little bugger appears to be behaving more predictably now that I have
uploaded the latest firmware (v0.9.2.2 AT Firmware.bin). 
Key finding to date? It needs a solid 3.3v PSU. I initially used a small
78L- style 3.3v regulator but the current draw (that fluctuates quite a bit
and goes up to 250mA) meant that the device was dissipating too much power,
getting too warm and pulling the rail down. 
I designed a meatier one yesterday with both 5v and 3.33v power regulators
and CNC'ed a circuit board to suit. It is operating very nicely now!

Onwards and upwards...

... Adrian