This is just a quick note: I’m currently breadboarding version 0.3 of the STM electronics – Hopefully I’ll have photos and results shortly thereafter.

New features of this version:

• 100% of John Alexanders’ analog STM design has been replaced with all-digital controls
• Greatly simplified electronics (but more complicated firmware)
• Microcontroller manages four channels: X, Y, Z movement, plus sample bias
• Teensy microcontroller (though the design is pretty microcontroller-agnostic at this point)
• Firmware tunneling current detection and PID control of Z height

Thanks to Steve F., and Efrain O. for their extremely valuable input to this revision.