Documentation/HallSensor.md
In sleep mode, the iron automatically lowers the temperature to 150°C (default). This default setting was chosen as it is just below the melting point of a wide range of solders. A lower standby temperature helps reduce the oxidation rate and prevent damage to the soldering tips. As a general rule, when not in use, unplug the unit or let it go into sleep mode to extend the life of the replaceable tips. The default sleep temperature can be adjusted to your preference.
Simply moving the iron or pressing any button will wake it back up into soldering mode. The sensitivity is adjustable. It is recommended to adjust this to suit your environment so that it reliably stays in sleep mode when not in use, but does not go into sleep mode when in use. (This may vary depending on the amount of movement during soldering.)
Inside the Sleep Menu is an additional type of sleep setting. Pinecil has an unpopulated footprint (U14) for a hall effect sensor, Silicon Labs Si7210-B-00-IV. After installing the hall effect sensor (HES), it is possible to auto-trigger Pinecil to enter sleep mode when it enters the stand, and Zzzz will appear (or text in detailed mode). This could be a fun enhancement for any Pinecil and adds a feature typically only found in more expensive high-end irons. The HES is available at many electronic stores for ~$2-$6.
After installing the HES on the PCB, place a magnet on the stand close enough to the sensor to activate one of ten user selectable settings.