Since the above question came up several times, here some more details on this:
To connect a thermistor to one of the free analog pins of the extruder controller v2.2’s Arduino chip, besides the thermistor itself, two additional electronic parts are needed:
- 100k Thermistor (e.g. from here)
- 4.7kΩ Resistor
- 10µF Capacitor
Here’s the schematic:
I soldered the resistor and capacitor directly onto a connector:
This “adapter” is then connected to the -then- unused analog pin 6 on the extruder board:
[Update 03/21/10: Just to clarify: YES, the red labels in the diagram below are correct! The labels in the board's silk screen are wrong!]
That’s it for the hardware side.
To handle the new input on the software side, the firmware of the extruder controller needs an update.
See my last post for more information on this. There’s a patch for the board firmware itself and one for ReplicatorG (for visual feedback and to enter a target temperature).
All these changes are also part of the next firmware/Replicator G release. All the sources are available through MakerBot’s public GIT repositories at http://github.com/makerbot
Schematics based on http://make.rrrf.org/ec-2.2