## Project notes 2022-10-30 (Logger calibration and code development)

The Tiny Logger hack quickly becomes a project on its own. First, the code compensates for the measured offsets between ESP8266 ADC-reading (10-bits) and the measured voltages. Then, the voltage divider factors were applied, and in the end, it came out what you can expect with this level of parts and instrument available to me. A quick summary is as follows:

- In the low voltage battery range, the relative error is < 1%, except for the very lowest voltages (i.e., 2.5V), which increased to 2.5%.
- In absolute values, it corresponds to < 30 mV, except for the last point (60mV).
- The relative error is < 1% at the lower end of the scale and increases almost linearly to ~2% for the high voltage pack case.
- In absolute values, it corresponds to 50 mV and up to 200 mV at the highest voltages.

One has to be satisfied with the results, considering these inexpensive parts, the short time spent, and not digging deeper into these inaccuracies.
For the code itself, I'm adding a tiny menu to be able to start, halt, and break the logging to the SD card. What remains is to add date- time stamps to the log and to complete the SD-write part. A GitHub repository is halfway ready to go public with all coming fume extractor code, including various utilities - thus, this is what I will do in the coming days.