extruder hot end wiring for uno

hi.. i am new to 3d printing... and i am doing this for my final year project ..
I tried to built a 3d printer setup from old cd drives, and easydriver with arduino UNO.
i bought mk8 direct extruder , but i really dnt know where to connect the thermistor and heater.
when i configured with teacup the thermistor pin was set to AIO3 and heater was AIO2.
after lot of search , i assumed that thermistor wire should connect directly with uno pin AIO3 and grnd, and not sure about heater )
please help me to wire the hotend and heater to the UNO.
thanks in advance

Digital IO pins are (more or less, some tolerances) only for 0 or 5v in or output
Analog IO pins are only for 0 to 5v in or output.

For the hotend you need a mosfet to turn the 12v on and off

The thermistor is just a resistor that changes value when heated. You do use an analog in pin, But you don't tend to read it directly... see [learn.adafruit.com]

Also take a look at the ramps circuit diagram for how its done using standard reprap parts

[reprap.org]

Take a look at the thermistors section, how they use a second resistor and a capacitor. The plug is where you wire in a thermistor. thermo0 (1 and 2) are the analog lines into the controller.

Now take a look at heaters and fans. On a ramp D10 is the hotend. The plug on the right is where you plug in the hotend.
Note how the pin p$5 is always 12v, this type of mosfet actually controls the -ve line.
The led and 1.8k resistor are optional.. its just so you can see when its on or not

Edited 1 time(s). Last edit at 03/29/2017 08:07AM by Dust.

Hello I am also new to 3d printers and generally in electronics so those diagrams don't help me at all, lol. Anyway in my case I'm using Arduino uno too + cnc shield v3 and using teacup firmware also and I have the same problems too. On the picture is the cnc shield AIO3 is the 3rd one so its A2 on uno cause its counting from 0 and it goes to resume pins on cnc so I plug there my thermistor but when I open pronterface it doesn't seems its working cause it keep ssaying my temp is at 130C without any heater working. As for the heater I don't know where I have to plug it too. Ive heard that I need a mofset as u said so I can plug it to cnc shield but the question is does the mofset then need analog or digital pin? also on teacup as karthesh001 said heater is set on AIO2 and it doesn't let me to change it ,doesn't give me more options on drop down list, do I have to manually change it on codes or something? Plz help me out and try to explains in simple way cause I don't have knowledge on those things . Thank you in advance.

Re thermistor

The pin looks correct, but I bet you just plugged the thermistor wires into to the resume pin and the black pin next to it.

This will not work.

Firstly the black pins on the right are all GND's

what you need is a additional resistor and a capacitor

This is what you have

gnd   --------------------------------------   thermistor wire
resume -----------------------------------  other thermistor wire

what you needs is

gnd   --------------------------------------   thermistor wire
                              |
+5v ----4.7K--------+10uf------
               |
resume -----------------------------------  other thermistor wire

Edited 1 time(s). Last edit at 06/20/2017 08:27AM by Dust.

re hot end you need a mosfet driver that can be switched with 5v input.

eg [reprap.org]

The signal wire to turn on is then just connected to the hold pin of that cnc v3 board.

This need a digitial pin, but all analog pins can also be digital pins, but the reverse is not true.


BTW You can find some nice documentation on this cnc v3 board [forum.hobbycomponents.com]

Edited 2 time(s). Last edit at 06/20/2017 08:43AM by Dust.

Thank you for ur reply ill look into it and let u know if it worked.

Ok so I set up the thermistor as u said with the resistor and the capacitor wired on resume and GND and tested it on ardiuno and its working. the problem I have now is that in pronterface it doesn't show me the right temp it only gives me a temp about 130 C either I have the thermistor plugged or not. In teacup I have defined the thermistor with most default inpus except the beta which I changed. So is it a pronterface problem or teacups and how can I solve this? How can I check if teacup can see my thermistor?

Edited 1 time(s). Last edit at 06/26/2017 11:03AM by Alexandier.

Right, I got a moment to try this myself.. We are out by 1pin

If we look in arduino_168_328p.h we find #define AIO3_PIN PINC3

So we are looking for PINC3 on the uno

If we look at



we see that this is A3, the 4th pin from the left on that block of pins in your image

This is wired to CoolEn line of the shield.



I have tested this and it works fine on teacup using the default pin of AIO3.

Edited 2 time(s). Last edit at 06/28/2017 03:26AM by Dust.

Yes thank you so much but figured it out too seems I had the wrong pin on cnc cause AIO2 is actually pin 2 on uno, so I have mine plugged there,also have plugged my heater on AIO1 or resume pin on cnc shield. Sty for haven't replied all this time but I was bussy fixing my printer and when I'm finally done and make ot work ill try to write a full guide on how to build 3d printer with uno and cnc cause this info lacks on net imo.

Ok have one more question and I hope my last . Its not on the same subject but I don't really like to open lots of posts. Anyway I have calibrate my extruder motor so I can know how much steps it needs per mm , I did that the classical way, measure some distance on the filament , tell motor to extrude a known distance and measure again. But when I do that again with my heater on and extruding filament my motor doesn't feed the same amount of filament as I measured when the heater was off. I hope I can make sense. so my question is where does the problem occur? is it the motor current? I sit the feed rate? is it the speed of the feed? is it something else? I'm using Bowden method and a 4mm nozzle. there is no jam or block filament anywhere I have that checked. So what others parameters can affect that problem so I can check it? thx in advanced.