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Can the smoothie handle 4 drivers from one output

LPC176x can source or sink 4mA on pin configured as output.
So, for example:
DRV8825 - max 100uA input current. You can drive over 40 of these.
A4982 - max 20 uA, > 200.
TMC2100 - max 30uA, so > 133 can be driven directly.

Check electrical characteristics section of the driver, find input current. Divide 4000uA by specified input current and You will know how many drivers can be connected directly. That's assuming everything works on 3v3 logic level.

Re: Multiple steppers. by SarephSareph, 10 Dec 2016 22:46

Thanks Arthur

Re: Multiple steppers. by preb1preb1, 09 Dec 2016 14:37

Level shifters are traditionally used to take a 3.3v pin and bring it up to 5v.
However, they have the added side benefit that they can ( most of the time, check yours before buying it ) handle much more current than a pin too.
Search google images for level shifters and you'll find a ton of schematics of how to do this, it's pretty easy.
Level shifter input to Smoothieboard pin, level shifter output to the 4 driver pins, done.

Re: Multiple steppers. by arthurwolfarthurwolf, 09 Dec 2016 14:35

Wow what a quick reply. Thanks but can you explain further. I am not an elctronic whizz.

Re: Multiple steppers. by preb1preb1, 09 Dec 2016 14:34

I think 4 drivers is going to be too much for Smoothieboard's puny pins.
However, you can solve that issue with a $2 level converter.

Re: Multiple steppers. by arthurwolfarthurwolf, 09 Dec 2016 14:32

Just joined the forum as looking to purchase a smoothie board and in need of advice.

Almost finished my laser and at the stage of buying and fitting the electronics. I have been thinking about the smoothieboard for sometime and think it will handle all my needs except possibly this one.

My lifting Z table is 1200mm x 600mm and I have fitted leadscrews at each corner to raise and lower it. These are driven (or to be driven) by 4 nema 17 steppers. One on each screw. I thought about one motor and driving the other screws by belts but could not find any belts long enough.

My question is this. I want to drive the 4 steppers together as one axis. Can the smoothie handle 4 drivers from one output. Does it have enough current. I think most drivers only need a few millamps and most controller boards the current must not exceed 100 milliamps I think. I have seen in the smoothie documentation that you can links the pins of 2 outputs together. Could I link the 3 of the axis on the 5x board together to produce enough to drive 4 stepper drivers?

if not does anyone have any ideas how I may be able to do this.


Multiple steppers. by preb1preb1, 09 Dec 2016 14:30


Smoothiebrainz is Open-Hardware, so it is allowed.


I am new to Smoothieware.
I just made myself a Smoothiebrainz-Board and it seems to work as far I can figure it out now.
I want to use the TMC2660 motordriver for my deltaprinter and I got some breakout-boards for testing purpose. The chip works fine with the arduino library, but I have problems to get them running with Smoothieware. (Nothing next to weird vibration + hot motor)
Before I continue testing: Does anybody has some experiences with the Advanced Driver Module or can tell me what to take care of?

PS: I have made two more SmoothieBrainz Board then I need and I would like to sell them. Is this allowed here?

Just before you try to print, where is the head located, and what does the M114 command return ?

The developpers of Smoothie use this method to compile :

And any text or code editor or IDE to edit the source code.

This is the only supported way of coding for Smoothie.

I'm wanting to be able to make changes to the smoothie source code within an IDE. I have had older builds compiling on mbed but have had trouble running newer versions.
What IDE do the smoothie developers use? Any help would be awesome.


12.5 x 24 is 300, yes.
Note you don't want a bed that is "just" 300W, you want one that is 12.5A at 24V ( ie with the right resistance )

However, when pushing to the absolute maximum of the board, any kind of mistake will have more dire consequence than in the "norm". I strongly recommend if you really have a need for power, you should just use a SSR. It's not very expensive, it's simple to setup, and it's much safer even at higher powers.

Planning on setting up my Folger FT5 with a SmoothieBoard. From the docs I see it can handle 12.5a at 24v. So in my mind that means I should (max) be able to handle a 300watt bed heater, no? Alternatively if someone can point me to the most powerful bed heater the board supports.

Not enough PSU current ?
Maybe try setting your homing speeds lower and see if it works better ?

Re: Homing Mystery by arthurwolfarthurwolf, 07 Dec 2016 18:07

I recently replaced my smoothie board and in setting up the new one, I am having a homing problem. I have checked the end stops using M119. They work as expected. I can home each axis independently and using M114, can see that it worked. But, when I try to home all three at once, the x axis motor starts to vibrate and movers very very slowly until it completes the home. Brand new config and new Edge download.

Homing Mystery by Craig AndersonCraig Anderson, 07 Dec 2016 18:06

Hi. This has been sort of been discussed before. The most related post is t-1630644
I want to wire closed loop Coolmuscle steppers that have their own drivers.
The driver's specs for Stp and Dir signal are 3.0 to 24V and 7-15mA
So smoothieboard is Ok regarding voltage (3.3V) but not current, as it can only deliver 4mA, right?
Worst case I could use level shifters as Arthur says they can output 220mA in the related post.
However, I would prefer a more immediate solution if possible. Would open drain as described in the general-appendixes article work with an external supply for more than 4mA as this driver needs? Or does the 4mA limit still apply ?

First I should say my main power supply is 24V and attached here I also have a 5V, 3A supply.

I would wire it as follows:

  • +Stp and + Dir from the external drive to an external +5V supply (or do I need to wire it to the limit switch 5V as in the previous article?
  • -Stp and -Dir from the external drive to smoothie St and Dir pins respectively
  • Ground pin from external drive I will leave disconnected as the coolmuscle will be grounded through the printer frame to the 24Vsupply (-) . Or should I connect this to smoothie GND pin (next to St and Dir pins) ?
  • I don't plan on using the enable pin on smoothieboard and will just wire directly:
      • 24V power from stepper to external +24V on supply
      • Power ground from stepper to external (-) on supply

Also I will need to enable Open drain for all St and Dir pins like:
alpha_step_pin 2.0o
alpha_dir_pin 0.5o

Does all this seem right?

For anybody interested on doing this setup, in order to make the coolmuscle work with steps/pulse and direction, k36.1 must be set to 1 in the coolmuscle setup

Thank you all :)

Just added to the custom menu and they works, except the beta tower one,
I' m using them to calibrate the bed manually, as my frame is perfectly aligned and the bed surface is
Machined, I do not need the bed levelling routine to work.
Just to be clear, all the towers are aligned and the end stops are working at the same equal distance, (optical ones) with 0,02 error at every zero axis. I cannot ask for more.
Smoothie is an original one, not a Chinese cheap one (maker base) running Smoothieware.
Last thing, even if i put manually the nozzle to the Z0 pos. and i trigger the Beta axis macro it rise up the nozzle to 124mm and always to 124mm and only to the beta tower, i even swap the numbers from positive to negative, nothing change, is always the same at 124mm.
Is this one a bug of the firmware?(maybe?)
I tried even another smoothie from another printer, nothing change :-((

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