I had some slight problems with my extruder motor, but upon fixing them more problems sprang up. As soon as I start the reprap host software, the PWM driver board starts heating the barrel. It heats it to maybe around 60*C, while the output reads a constant 17*C. The thermistor I'm using is the EPCOS 100K Thermistor (B57540G0104F), the thermistor reads 100K ohms at room temperature, and I compiled and uploaded the code with the correct temperature, so that shouldn't be the problem. Does anyone know what else could have gone wrong here? Another problem I'm still having is that the extruder motor will occasionally not turn on (the DC motor driver board won't respond to input from the host software)

See if the problem goes away when you disconnect the USB connection.

You maybe having problems with the common grounds between your PC and your reprap equipment and you are getting ripple currents.

Another is that it will automatically run the last program that you uploaded into your control processor; so load something that is basically idle and startup routines for the bootstrap program should automatically turn the output's off.

This is probably not your issue, but i had something similar happen. turns out i had my pinout from my sanguino incorrect. the pin wasn't an output for anything, so it was just floating and told my PWM board to turn it on.

however, if your thermistor is still detecting 17C when the temp is obviously higher, then that probably isn't your issue. try setting the temp to something under 17, if the heater shuts off, then your thermistor/board/heater tables are messed up.

andres