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irishbeard

Controlling analog pins as digital pins in Marlin

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Posted (edited) · Controlling analog pins as digital pins in Marlin

Hi,

I'm interested in controlling some of the analog (ADC) pins as digital pins on the Ultimaker 2 board. I've seen that this can be done in Arduino using digitalWrite (https://www.arduino.cc/en/Tutorial/AnalogInputPins) and it also seems like it is possible to control them using the M42 command in marlin (http://marlinfw.org/docs/gcode/M042.html). Has anyone tried this or know if this is correct?

I've found the pin map for the ATmega 2560 (https://www.arduino.cc/en/Hacking/PinMapping2560) and can determine the pin locations using the Ultimaker 2 schematics. However, I'm not sure how to interface with the ADC0-11 pins (M42 PA0 S255 doesn't work). Do the analog pins have a digital pin equivalent on the Ultimaker 2 board (ex: A0 = digital pin XX)? Do I need to set this up myself in the pins.h file?

Any ideas / comments are greatly appreciated! :)

Edited by Guest

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Posted (edited) · Controlling analog pins as digital pins in Marlin

Note that on an UM2 board, you have 3 digital pins available: Exp3 and Ext/IO (ports 13, 30 and 38 ).

If you really need to go to analog ports, A0 is port 54 on the Mega (so M42 P54 S255 should work)

Edited by Guest
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Posted · Controlling analog pins as digital pins in Marlin

Note that on an UM2 board, you have 3 digital pins available: Exp3 and Ext/IO (ports 13, 30 and 38 ).

If you really need to go to analog ports, A0 is port 54 on the Mega (so M42 P54 S255 should work)

 

Thanks amedee, this is really helpful! I will use more than 3 pins so that is why I want to use the analog pins as well.

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Posted (edited) · Controlling analog pins as digital pins in Marlin

I found P13. I only need one pin. Thanks

 

Edit: It appears to be a PWM and the output is very noisy.

Edited by nrobinson2000

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Posted (edited) · Controlling analog pins as digital pins in Marlin

You can lookup the locations using the mega2560 pinout and the Ultimaker2 board schematics. Pins 30 and 38 are on EXT/IO which is terminal J23. Top (1,2) are ground, middle (3,4) are 5V and bottom (5,6) are P30 (PC7) and P38 (PD7).

atmega2560v3.png

EXTIO.png

um2 board.png

Edited by irishbeard
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