Hey, no, there are no pullups in the schematic, afaik. And yes, the pullups are enabled on all analog input pins in Arduino firmware (farmbot_arduino_controller.cpp) to reduce the number of things that can go wrong with unused ports. The default soil moisture sensor seems (!?) to provide enough current to outvote the pullup. Experimenting with other sensors like capacitive moisture sensors or distance sensors will generate wrong values due to the enabled pullups.
At the moment there are two solutions:
- compile custom firmware for Arduino with pullup disabled (until next automatic firmware update…)
- use this farmware
(3.) wait until new scheduled software fix in webapp, introducing a pin type “analog_no_pullup”
Analog pins without pullups and nothing connected read as random values, as can be tested using the above farmware on an unused pin.
Poking the moisture sensor twice in the same place, right after another, returns dryer readings the second time. This is due to a thin layer of air along the sensors surface in the second measurement. At least this is a result, I get repeatable with a capacitive sensor.