Expanding the RUMBA to a fourth extruder

Hello everyone,

Let me first start by telling how great this forum is. Until this day I haven't had the need to register myself because all the information I needed I could find by using the search function. Kudos to all the people who came before me and figured this all out!!

But now I have an issue by which I can't find very much information about... I would like to add a fourth extruder to my RUMBA so I can finally use my Kraken at full force. I think I found all necessary information, but before committing to the build I wanted to make sure that my thesis would be sound and I don't burn anything....


In pins_RUMBA.h (Marlin RC7) I read a comment that it is possible to add a fourth extruder.

//optional for extruder 4 or chamber: #define TEMP_X_PIN         12   // ANALOG NUMBERING - default connector for thermistor *T3* on rumba board is used
//optional FAN1 can be used as 4th heater output: #define HEATER_3_PIN       8    // EXTRUDER 4

But I didn't find any explanation which pins to use for the fourth extruder. So I looked at the RUMBA schematics (you guessed [email protected]) and checked out the EXP3 header pins. Together with the Arduino Mega 2560 PIN mapping table I figured out which pins on the RUMBA where the ones used in the Marlin code.
Now I wanted to be sure that I picked the right pins for the job and this is why I posted this thread.

Can someone please confirm that EXP pins 5(STEP_PIN) --> (pin 4 in the code), 6(DIR_PIN) --> (pin 5 in the code) and 7(ENABLE_PIN) --> (pin 63 in the code) on the RUMBA are free to use for the fourth extruder?



With kind regards,


Tom

Hey Everybody,

This must be quite the conundrum as nobody seems to be able to provide me with an answer...No problem though.
I'm answering my own thread because (I think) I found an error in the RUMBA schematics mentioned earlier. I already sent a pm to the creator of the file, but his/hers last activity was in 2013 so I don't figure I will be receiving an answer from this person very quickly...
So I'll post my findings here and maybe someone can confirm that I'm right or wrong.

I believe that the pins for FAN0 and FAN1 should be switched around. If I check the pins_RUMBA.h (Marlin) file and the Arduino Pin mapping table then they should be.


With kind regards,


Tom

Tom,
Did you solve your problem with EXP3? I've been trying to find info on the EXP3 pinout for weeks, with no real leads.

Jeremy