Firmware Problems

Hello, we are having a problem with our extruder shutting off when it reaches the proper temperature. So far we believe it is the firmware, but none of us have any programming experience. If anyone has gotten their firmware to work with a thermistor and is familiar with the programming, we would really appreciate it you could take a look at our firmware and point out what we are doing wrong. If you PM us with your email address, we can send you the file.

Thanks for any help/ideas.

Ryan

Make sure that the right thermistor table is in the firmware code. That is for both the motherboard and the extruder board. There are different model thermistors that require different tables of data to be loaded in the firmware. Which model thermistor do you have?

We are using the thermistor from digi key

[search.digikey.com]


When the extruder board is not powered up, the software reads T:0, but when the extruder board is turned on, even if the thermistor is unplugged, the software flashes back and forth between T: 231 T: 232 and T: 233.


We are so close to being finished, any help would be greatly appreciated!!

-Ryan

Edited 1 time(s). Last edit at 08/10/2010 06:24PM by HSRepProject.

If the thermistor is unplugged then the reading you are getting is from the firmware hitting the end of the lookup table. That is how it is suppose to work. However why it flips between the values you state I am not sure, but my suggestion would be that you have a resistive short where the thermistor is plugged in, and this is causing the firmware to detect a resistance value and thus return a value for the temperature. (I am just guessing of course ;-))

How would we go about testing for a resistive short on the board? What would cause something like that?

Thanks,

Ryan

Sorry been away. I would just use a multimeter and just check that with out the thermister connected measure the resistance between the two points where the thermistor would be attached. I believe it should indicate an open circuit
(I could be wrong)

David