nanoDLP

TheAtomicSoul

Member

Registered: 2017-11-06

Posts: 5

Pi3 Direct Drive Wiring Help

I am in the process of building a direct drive resin printer and found the schematic (https://www.nanodlp.com/download/schematic.png), but I am not good at reading diagrams and am kind of confused by it.

Is there a possibility anyone could take a look at the linked picture and tell me which letters and numbers connect to each other?

https://drive.google.com/open?id=0By420 … XF6QzRTTVE

bigfilsing

Member

Registered: 2016-11-20

Posts: 306

Re: Pi3 Direct Drive Wiring Help

send me a link to the banggood stepper driver board pls and ill see if i can help out

juliendelnatte

Member

Registered: 2017-06-07

Posts: 84

Re: Pi3 Direct Drive Wiring Help

I'm currently building too a direct drive resin printer and I made a custom PCB with a lot of feature. You can check it here : https://plus.google.com/100170060322292 … 9180118782

TheAtomicSoul

Member

Registered: 2017-11-06

Posts: 5

Re: Pi3 Direct Drive Wiring Help

send me a link to the banggood stepper driver board pls and ill see if i can help out

I'm using a A4988/DRV8825 3D Printer Stepper Motor Driver Control Extension Shield Board GM
with a Hobbypower StepStick 4-layer DRV8825 Stepper Motor Driver Module A4988

I'm trying to wire this directly to the Raspberry pi3 (based on the prior linked diagram) in order to reduce the cost for the build.

bigfilsing

Member

Registered: 2016-11-20

Posts: 306

Re: Pi3 Direct Drive Wiring Help

Hi . Yes i understand your intent but the only stepper driver they have on the BG website has 3 pins on the right hand side not 4 pins like your photo ( KLMN) and the resolution of the photo isnt good enough to read the PCB screen print.
Reference https://www.banggood.com/A4988-DRV8825- … rehouse=CN
Im wondering on your board what the 4th pin is for ? 
The others are
E ( enable) (pin16 on raspi)
D ( direction ) (pin 15 on raspi)
S ( step) ( pin 22 on raspi)

AS for the step stick module, it can be A4988 or DRV8825 but not both !?  it is very important which you have because of the orientation when you plug them in is different. Be careful

Batmario

Member

Registered: 2017-09-19

Posts: 3

Re: Pi3 Direct Drive Wiring Help

Hi, I've made some PCB's following the diagrams on the download section, unfortunately the BOM is not complete and some components are no longer in production. Has anyone done something like that and could help me? thank's

TheAtomicSoul

Member

Registered: 2017-11-06

Posts: 5

Re: Pi3 Direct Drive Wiring Help

Thanks bigfilsing; I've found a few images that have helped clarify some of the connections on the stepper motor driver so I named them accordingly on it (instead of going aplhabeticaly on them.)

The 4th pin is "G", which I assume is ground(?)
I don't see a line/path from it to any of the DRV8825 connection points.

I'm using a DRV8825 Driver Module on the Stepper Motor (v1.1) expansion board.
I added the DRV8825 board layout to my image and was able to verify this is the layout that is on the expansion board- and the correct direction to mount it.

https://drive.google.com/file/d/1zJGUAE … sp=sharing
---
Here is the closeup of the board. The 4th pin is "G", which I assume is ground(?)
https://ae01.alicdn.com/kf/HTB1XjTZQVXX … tional.jpg

bigfilsing

Member

Registered: 2016-11-20

Posts: 306

Re: Pi3 Direct Drive Wiring Help

Yes, i think its fair to assume the 4th pin is ground and a reference for the S,D & E signals.

Set all the DIP switches to "ON" to give 32 microsteps on the DRV8825   ( 200 X 32 = 6400) So 6400 steps will give you 1 rotation of the stepper motor ( assuming you're using a 1.8 deg stepper motor = most common Nema 17)

VM and the adjacent G(nd) pin are for 12VDC for the motor ( needs at least a 1.5 amp power supply)
5V & G(nd) are from the Raspi
( note its always important that the Gnd from the Raspi & Gnd from the VM are tied together which I believe is the case on the 2 middle pins of the 4 pin power in arrangement)

TheAtomicSoul

Member

Registered: 2017-11-06

Posts: 5

Re: Pi3 Direct Drive Wiring Help

I just pulled the paper for the stepper motor a moment ago; it's a 0.9 degree stepper motor.  (I think that gives a higher degree of detail?)
(I had originally bought a few of the parts I'm using for this for a PLA printer I had planned to build.)

bigfilsing

Member

Registered: 2016-11-20

Posts: 306

Re: Pi3 Direct Drive Wiring Help

SHould indeed give a finer resolution.  All it means is that 12800 steps will equal 1 rotation.
If for example, you use a lead screw with a 2mm pitch, 12800 steps will give you 2mm of Z travel.

Not sure exactly with direct control but normally a "steps/mm" ( steps per millimeter) is required as a configuration input So using the example above you would input 6400 as being the steps required to travel Z 1mm