C3D(Mini) Trouble Connecting External Drivers


(Nico) #1

Machine: Custom Build Machine
Board: C3D(Mini)
Firmware: GRBL-LPC (Self-Compiled, based on https://github.com/cprezzi/grbl-LPC )
Stepper Drivers: 4x (X,Y,Z,A) Stepper-Online DM556T (Official Leadshine Clone/Light-Version)
My Cohesion3D(Mini) Board is connected to +24V and USB(RaspberryPi)
My Stepper drivers expect binary-0 to be 0-0,5V and binary-1 to be 4.5-5V ( http://www.leadshine.com.ua/pdf/dm566.pdf page 3)

Hi,
I have some trouble connecting my external stepper drivers, while setting up the “enable” pin for my first driver:

  • I have connected (EN+) to the +5 V Pin at my Cohesion3D(Mini) Board and the “X-enable-signal” of the Cohesion3D with (EN-) based on the directions on the homepage

  • A high Pegel on the output of the C3D measures 3.3V Resulting in a 1.7V “low-signal” at the stepper driver. 5V-3.3 = 1.7 --> “1.7V > 0.5V” ==> above the expected 0.5V upper limit of “binary-zero” for the stepper driver
    A low Pegel on the output of the C3D measures 0.0V Resulting in a 5.0V “high-signal” at the stepper driver. 5V-0V = 5V --> “5V > 4.5V” ==> acceptable.

Based on these measurements, the observation “Motor not moving” can be explained by the invalid pegels based on the stepper drivers expectations.

  • Are there true schematics for the C3D Mini (not just external connection diagrams)?
  • If there are no schematics, would someone please confirm that the stepper outputs do not have level shifting and are direct 3.3V I/O pins
  • what is the current limit for these I/O pins ( it seems i need to design a level-shifter/optocouplers circuit to get my drivers working if my assumptions are correct )

Btw. unrelated to the previous question: Do I need +24V external power connected if I am only using external drivers?

Kind regards,

Nicolas


#2

There are prebuilt ones here with many variations to account for external drivers:

These builds rely on the drivers being wired as shown in this guide:

https://cohesion3d.freshdesk.com/support/solutions/articles/5000744633-wiring-a-z-table-and-rotary-step-by-step-instructions

If you wire with the common 5v and the - signals going to the pins then you should leave the enable disconnected so that the driver is always energized.

Please show some pictures of your setup and wiring, and then we can look into this in more detail.