Re: dzach's Hadron build
Posted: Sun May 06, 2012 11:47 am
After reading the above links, I see that the Arduinos have an issue with reading multiplexed analog imputs fast, and another issue with the reference voltage for the ADC not being regulated.
I disconnected the heated bed thermistor and run the test again. Strangely enough, the disconnected input continued to measure temperature without the thermistor, possibly because the multiplexer does not have the time to completely switch the input between readings.
In the above test, the thermistor was at room temperature up to about point 70, at which time I put the soldering iron at a distance of about 1cm from the thermistor and left it there for the rest of the test. The readings showed the change immediately, but there still exists a huge fluctuation and missed readings. In the plot above, the heated bed thermistor is DISCONNECTED but I still get a reading close to the one from the extruder.
The reading are taken using the M105 code with Marlin 1.0.0 RC2 running in an ATMega1280 RAMPS board.
I disconnected the heated bed thermistor and run the test again. Strangely enough, the disconnected input continued to measure temperature without the thermistor, possibly because the multiplexer does not have the time to completely switch the input between readings.
In the above test, the thermistor was at room temperature up to about point 70, at which time I put the soldering iron at a distance of about 1cm from the thermistor and left it there for the rest of the test. The readings showed the change immediately, but there still exists a huge fluctuation and missed readings. In the plot above, the heated bed thermistor is DISCONNECTED but I still get a reading close to the one from the extruder.
The reading are taken using the M105 code with Marlin 1.0.0 RC2 running in an ATMega1280 RAMPS board.