This device was originally made to use by the passenger when the Moble Logger was on the back seat while we were traveling. I received its input from the Mobile Logger via an an RF link.
This had a 4-digit 7-segment white LED display. This display failed and was replaced by a 2-line, 16-character OLED display. The program was expanded to include receiving RF data from the Solar Sensor and the master clock.
Now you can buy smaller Arduino boards I have now used one - a "Mini Pro" - to make a portable sensor with the same OLED display.It is completely self-contained and battery-powered. Since it is to be used hand-held it turns itself off if not in use. When off, the battery current is negligable, so it uses 2 AA non-rechargable batteries which may last for years.
It has three sensors which are on tiny "breakout" boards. All use I2C communications, as does the display. Two of the sensors: a BME280 Pressure-Temperauure-Humidity and a HMC5883L magnetometer have been in my "New Stuff" box for a long time, so they are not the current version. The third, a DS3231 is a temperature-compensated time-date clock.
It also provides additional preferences pages for selecting the pressure readout as either altitude or barometric pressure, and for presentationn of all values in either Metric or American units.
Photos. circuit diagrams, and the programs are provided for all three versions. The details are described in these links:
|Here are photographs and explanations
Here are the circuit diagrams
|Here are the programs for all three versions