Welcome! Log In Create A New Profile


Problems w/ thermistor & TeaCup

Posted by larsrc 
Problems w/ thermistor & TeaCup
June 30, 2013 05:59PM
Hi Teacuppers,

Since my last mail, I have upgraded to a Teacup-capable Arduino, and successfully used it with the manual control panel in ReplicatorG. It moves in all three directions and heats, but I can't move the extruder (I expect due to refusing to move a cold extruder) and worse, the temperature reading is totally off.

I have a plain thermistor built into the Wade's Extruder I got. I have a 4.7K resistor on it, and it responds quite nicely when I test it with the attached plain Arduino program. However, when I try reading it with Teacup through ReplicatorG, the temperature readings are 0 C at the beginning and then at some point (not clearly related to the temperature) jumps instantly to 3800 C - which I'm sure I would notice if it were true. So i suspect it's something in my setup for the Teacup. I've attached the config files for it, though I don't think there's much room for error. Am I forgetting something obvious?

As part of looking into this, I was a bit puzzled by this part of temp.c:

do {
uint8_t j, table_num;
//Read current temperature
temp = analog_read(i);
// for thermistors the thermistor table number is in the additional field
table_num = temp_sensors.additional;

Shouldn't the analog_read() call be using 'temp_sensors.temp_pin' of the appropriate thermistor entry, rather than just 'i'? Same on line 229. I imagine this works for the common case of a few thermistors lined up on the first few analog pins, but it's ignoring the pin setting in the thermistor definition. Not that this can explain my problem, alas, as it occurs whether I use pin 0 or pin 1.

open | download - config.monster.h (23.2 KB)
open | download - ThermistorTable.monster.h (3.2 KB)
open | download - TemperatureTest.ino (677 bytes)
Re: Problems w/ thermistor & TeaCup
July 02, 2013 06:25AM

(I expect due to refusing to move a cold extruder)

Wrong assumption.

Teacup extrudes when you send G-code to do so, no matter how warm the hotend is. You should be able to move the extruder with G1 E20 F200.

Generation 7 Electronics Teacup Firmware RepRap DIY
Sorry, only registered users may post in this forum.

Click here to login