[SOLVED] Arduino UNO with TeaCup - problem with thermistor 100k ohm

Hi.
This is my first 3d printer, also my first post so forgive me if I'm writing in wrong place.

I have Arduino UNO atmega328p with TeaCup on the board.

I can't deal with temp reading from my NTC thermistor 100k ohm.
Thermistor works fine (I checked resistance while heating him). Also calculate beta: 3497

I don't have any module to get temp values, so i build one basing on NanoHeart sensor


My TeaCup settings:


Repetier Host points to 0C tem. Pronterface shows 116C:



Could you give me some advice what I'm doing wrong ?

Edited 2 time(s). Last edit at 04/04/2016 05:52AM by asrt.

Umm... (its late so I may be quite wrong)

But it looks like you have gnd on one side of your thermistor and +5 on the other side

This isn’t correct... one side of the thermistor is meant to be ground, that’s fine

The other leg of the thermistor is connected to your analog line and is pulled up to vcc via the 4.7 resistor and is coupled to gnd via the capacitor

ie move the +5v right one hole, and move the top of the resistor right one hole also, then you have to join with a wire the thermistor pin down to the point between the resistor and the capacitor (you going to have to move that capacitor down one to create a hole)

having gnd and +v5 threw the thermistor, you only heating up the thermistor (this may have damaged it)

NB im just using the standard ramps circuit, which will work on any 5v arduino

Edited 4 time(s). Last edit at 04/03/2016 07:31AM by Dust.

Thank You for quick response.
I made some changes:


But still without result.
Repetier Host points to 0C temp. Pronterface shows 133C

Circuit looks good now...

Did you configure teacup to use A3 (looks like a3 from the picture)

while looking at pronterface, unplug the thermistor, does the value change? (should drop to 0c)
you can also replace the thermistor with a variable resistor (100K) 100K is normaly 25c, lower values shows a higher temp

how did you test the thermistor? a bad way to test it is to put it in a lighter, sadly this kills them as lighters are > 1000C and it not deigned to survive that

I put thermistor and thermometer to hole inside hot-end. Heated it to 180C and measure the resistance on both ends of thermistor.

I configure my teacup like on screen at first post (AIO3), from drop-down menu I can chose AIO1,AIO2 and AIO3.
I don't see any AIO3 on my arduino, so I'm guessing its Analog in pin A3. Is it correct ?

Unplugging thermistor causes drop temp. to 131C
Unplugging A3 cable causes temp. rise to 204C


P.S sorry for my English I haven't used it for a while.

Edited 3 time(s). Last edit at 04/03/2016 01:01PM by asrt.

I try to see what arduino sees on Analog pins.
I uploaded code:

void setup() {
  Serial.begin(115200);
}
 
void loop() {
  int val;
  val=analogRead(0);      //Read the analog port 0<- this value was modified in range [0-5]
  Serial.println(val);
  delay(1000);
}

I checked values from all pins, holded thermistor in hand for few seconds, and putted him away for a while.
In room temp was 27C, in hand 31.
Below are my resoults:

A0, A1, A4, A5:
In room temp. value = 966
In hand temp. value = 964

A2:
In room temp. value = 694
In hand temp. value = 694

A3:
In room temp. value = 468
In hand temp. value = 466

So I'm guessing that pin A2 and A3 are broken?

Edited 3 time(s). Last edit at 04/04/2016 02:57AM by asrt.

If two hosts report different results it's not unlikely they interpret Teacup's response differently. Conventions on how a temperature report should look like changes from time to time.

I'd send M105 manually ( = typing with the keyboard) to see what comes back. Pronterface also has a "Debug G-code" checkbox in its menu which turns on reporting all the traffic between host and controller.

---

Generation 7 Electronics	Teacup Firmware	RepRap DIY

[PROBLEM SOLVED]

Thank You guys for help.
I change AIO3 to AIO5 - temp was 0, if i pull out cable from A5 then temp rises to ~2000C.
I buy another 100k thermistor and replace it, but still arduino acts the same.
I tried with different resistors.
Finally I change beta and R2 to right value it works just fine:

In room temp. value:
SENT: M105
RECV: T:28.50/0.0
RECV: ok

In hand temp. value:
SENT: M105
RECV: T:28.75/0.0
RECV: ok
SENT: M105
RECV: T:29.25/0.0
RECV: ok
SENT: M105
RECV: T:29.75/0.0
RECV: ok
SENT: M105
RECV: T:29.75/0.0
RECV: ok
SENT: M105
RECV: T:30.0/0.0
RECV: ok

Difference from thermometer and thermistor is about 1 degre.

P.S if i try to use AIO3/AIO2 i still have different values, so i will stay with AIO5 for thermistor and try to build Heater on AIO4.
Wish me luck.

Edited 4 time(s). Last edit at 04/05/2016 10:12AM by asrt.

good luck and please share your results