Any chance of adding an extra extruder on a board without AUX port?

I have a dual extruder delta printer, the board connects to 2 extruders and 2 hotends.

Now I'm thinking about trying the diamond hotend, which will require an additional motor. Most of the information I can find are based on RAMPS board which has AUX1, 2 and 3 port for connection of additional electronics. But my board doesn't have an AUX port, the only unused connections are the X and Y min endstops, and maybe the 2nd hotend thermistor since diamond hotend only requires one. My questions are

Is it possible to reuse the X, Y min endstops and the thermistor pins for the extra extruder motor?

Is there any unused pins in the LCD and SD card connector? I believe I still prefer LCD and SD to be functional.


If the above options doesn't work, my old i3 printer has a RAMPS based control board which does seem to have a spare AUX port I maybe able to use, I can swap the boards of the i3 to delta but that means rewiring both printers and a lot of firmware tweaking since I don't have the source code of the firmware on the i3. So this is the last resort.

Thanks in advance for your advices.

Edited 1 time(s). Last edit at 06/15/2017 09:07PM by mianwo.

you need 2 IO lines minimal for step, direction

Preferably you should also have a enable on an IO pin, but you can just tie that to a rail and have it always on (check steppers and drivers aren't getting to warm if you do this)

So yes you can use X, Y min endstops
The thermistor pin is normally analog, you would need to find the appropriate digital io pin name for it, presuming it can do digital, most pins can.


Cant say re the lcd connector, since you haven't told us what board or lcd you have.

Thanks for the reply.

My LCD and SD card board is the most commonly seen RepRapDiscount Smart Controller LCD2004 with SD card reader, connected with 2 10-pin connectors. Although I currently have a 12864 graphic controller connected but it's easy enough to swap back if that gives me extra pins to use.

Regarding the thermistor pin, I read that all analogue pins can be configured and used as digital pins, but I don't pretend to understand the knowhow, is there extra configuration required in the firmware?
I use Repetier firmware, my understanding is i can simply find the pin numbers I want to use, and assign them in userpins.h, like these:

#define ORIG_E2_STEP_PIN 9 // This was the number for TEMP_2_PIN
#define ORIG_E2_DIR_PIN 22 // originally for ORIG_X_MIN_PIN
#define ORIG_E2_ENABLE_PIN 26 // originally for ORIG_Y_MIN_PIN
#define E2_FAN_PIN -1

#define E2_PINS ORIG_E2_STEP_PIN,ORIG_E2_DIR_PIN,ORIG_E2_ENABLE_PIN,

yes, the only issues is the analog pins are numbered separately to the digital pins numbers so A9 doesn't just become D9 its something else in the Digital side.

From what I can google I see
Port Pin Function
PF 0 54 A0
PF 1 55 A1
PF 2 56 A2
PF 3 57 A3
PF 4 58 A4
PF 5 59 A5
PF 6 60 A6
PF 7 61 A7
PK 0 62 A8
PK 1 63 A9
PK 2 64 A10
PK 3 65 A11
PK 4 66 A12
PK 5 67 A13
PK 6 68 A14
PK 7 69 A15

so A9 is D63 (I am presuming a mega2560 based board here)
There is also a warning that these ports have pull up resistors

re the LCD

from [reprap.org]

looks like you have D32, D47, D45 D43 and D39 all unused on the aux-4 connector