Forgive my newbiness. For the SparkFun IoT RedBoard - ESP32, where is the documentation describing each of the pins. I found the schematic on that web page. But, for example, when the schematic lists pin 5 on connectors J9 & J10 as 5 volts, is that always the case even when plugged into a 12v power supply, or USB-C power, or 3-4 volt battery power? What does “perfect diodes” mean? What’s the difference between “5V_EXT”, “5V_MEAS”, & “5V_CHG”? What does “battery fuel gage” mean? (battery power left?).
Keep in mind, I’m not looking for the actual answers to these questions, instead I’m asking where the docs are to answer these questions.
Thanks in advance
Ben
Our guide has some info, but for the most part the pins’ purposes are to be inferred/gleaned from the short-hand descriptor
5v EXT is the 5v line if you apply external power (barrel jack, 5v pin), 5v MEAS is the measurement line, 5v CHG is charging circuit line. These all need to be separate because: external power may need to be stepped down, you measure via a parallel circuit, charging circuit isn’t always active like the others (when used!)
There isn’t a tried-and-true dictionary of sorts, but you mostly look at the schematic and board (and eagle/kicad files if needed) to glean what the lines/pins do 