Extracting Motor speed and steps from Ramps 1.4

Hello fellow Reprap-Community,

I want to use the Ramps 1.4 Board to controll an extruder and other sensors. Though for the X,Y,Z-axis I want to use a independant system. For that I need the information of Marlin, how many steps, and at which frequency the individual motors should run (which can then easily be translated into position and speed).

As I understood it, Marlin interprets the given G-Code to calculate its own acceleration. Marlin then sends "on/off" signals to the individual pins of the stepper-motors at a certain frequency. Is it possible to extract that information in marlin?
If yes, how do I send it to an other microcontroller? Via one of the AUX-pins? (sorry I'm quite new to this).

Thanks in advance!!

... eventually simply extract the pins for STEP and DIR of each axis and feed them (together with GND) to the corresponding external stepper drivers?

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Thanks for the quick answer.
But what do you mean with "simply extract the pins"? Thats exactly what I was asking for... how do I do that in the code?

... why code? -- I'm inserting a "dummy"-socket into the stepper driver sockets, which feeds the 3 pins STEP/DIR/GND with a cable to the external driver ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Oh now I unterstand what you mean. The thing is, that I need the X,Y, Z-position, as well as the X, Y, Z-speed as values. Sure I could try to convert the measured steps and frequencies from the 12 pins themselves by converting my external microcontroller to a sort of oszilloskop, but I'd rather have a more elegant solution. Those 12 pins are fed a signal, do you know where that signal is in the code?

I'm thinking along the lines of: "the bipolar-X-axis-stepper has 4 pins on the ramps board. In marlin they have the initials pin_x1, pin_x2, pin_x3, pin_x4. The timing of their activation should be sent to an external microcontroller."

My problem is that I don't know the pin names, nor how to send any info to an external microcontroller..

... the position is not the problem - but the speed could be, as it's calculated (or better "stepwise executed") "on the run" and through a lookahead-buffer to synchronize XYZ with the extruder ...

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Oh okay. Well I'll try to solve it in a different way.. Thanks for the info!

@CDorn

" "the bipolar-X-axis-stepper has 4 pins on the ramps board. In marlin they have the initials pin_x1, pin_x2, pin_x3, pin_x4"

no such thing

Marlin only knows about the enable, step and direction io lines that control the stepper driver.
It does not have any direct control of the 4 ouput pins of the stepper driver.