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6wire 2phase 5Volt Steppers With Tiny G page 5

Started by akfreak on in TinyG Support. 65 replies, last activity Sep 8, 2021.

akfreak #12076

I checked all the connections and they are connected via the exact instructions you gave and Nadda. Note, With all of the signal connections unplugged, and only the A1 A2, B1 B2 (stepper coils), Vcc and GND connected vathe stepper driver the Motor is locked in place when I power up.

So I want to go over a few things so they are clear to me.
The Tiny G connections
3.3V is obvious (its 3.3v constant? and this is where I could hook a voltage translator to step up to 5V to drive the stepper driver with the correct voltage?)

Enable (bar, what is bar?) This must be a GND signal as you had me hook it to the ENA- side on the DM556.

Direction This must be a Positive Voltage signal as you had me hook it to the Dir + on the DM556

Step This must also be a Positive Voltage signal as you had me hook that to the Pul+ (aka Step +)

GND This pin must supply a GND signal as you had me hook it to both the Pul- (aka Step-) and the Dir-.

I did verify that the Motor Timeout Idle is set to 2 seconds, this says to me that there is a signal for 2 seconds telling the Stepper driver to lock the motor in place for 2 seconds then go to idle and turn off the signal that energizes the coils of the stepper motor.

While doing some research on stepper drivers and connections I see there are Two typical setups Common Anode (active low) and Common Cathode (active high). the Active low setup sends voltage from VCC to ENA+ DIR+ PUL+ and looks for negative signals to ENA- DIR- Pul- from the driver board (arduino/Rambo,gShield...ect) to complete the circuit.

On Active High ENA- DIR- Pul- all rest at GND and wait for a Positive signal ENA+ DIR+ PUL+ from the control board (Arduino,Rambo,gShield,ect....) to complete the circuit.

How is the tinyG setup? I am a little confused how the signals leave the pins.You had me use the Enable as - (negative signal) and Direction and Step as + (positive signals).

One would assume that the Enable, Direction, Step would be GND signals (but my assumptions are ALWAYS wrong)... Now I am curious, I am going to use my meter and see what what is what.

Thanks again. Tom

akfreak #12077

I think I may of found a problem. I measured the pins (I dont know what you call these pins, the holes above Motor 1 2 3 & 4., but the holes on my board have now pin headers installed, and I measured these pins with a voltmeter. The 3.3V measured 3.4v dc so we are good. the Enable pin also rests at 3.4V so this could be my problem.

"Connect Enable[bar] to ENA – on the DM556
Connect Step- and Dir- on the DM556 to tinyG Gnd (not DM556 GND)
Connect ENA+ on the DM556 to the 3.3V lead on J17"

Not Sure what "[bar] is, is it typo? Or, there is a little Bar line above Enable on the PCB. Anyways if the Enable pin on the DM556 is Active Low and we are sending 3.3V to ENA+ because its hooked to 3.3v on the tinyG and DM556 ENA- is hooked to the Enable of the tinyG resting at 3.3v this is an issue, no? Our enable circuit on the DM556 is 3.3V on both the negative and positive.

I am not sure how the controller works, if in fact it rests as a closed circuit and needs a signal to open the connection between the stepper coils to unlock it, this may very well be the problem. What do you think?

I am not going to mess with this until I hear from you.

cmcgrath5035Moderator #12078

I am not sure how the controller works, if in fact it rests as a closed circuit and needs a signal to open the connection between the stepper coils to unlock it, this may very well be the problem. What do you think?

I am not 100% sure what you are asking here, but I can guarantee you the detailed answer is well beyond the scope of what we can do here. Keep in mind that most all logic leads and the actual connection to the stepper windings are pulses, not DC levels that you can read usefully with a voltmeter. Perhaps what follows will help.

The Term "enable - bar", silkscreened on my tinyG as enable with a bar across the top, is standard speak in logic circuits that when I say "Enable is active", the enable -bar lead will be a logic low, approx 0 to 0.1V.
That is the way tinyG firmware signals Enable is active or inactive. The enable lead is programmed to be 'active-low' because that is what the onboard 8825 stepper driver chips expect.

Upon reset, tinyG will turn on the driver device for $mt seconds. During that interval, the step lead and dir lead will be off, and measure 0 volts.
When the stepper driver device sees enable on and pulse and dir off, the stepper device is signaled to hold position with pulsed voltage applied to all 4 winding leads at appropriate phases. After $mt seconds, the enable lead turns off, which is 3.3V.

Go back and see if you observe that behavior, voltmeter measuring the enable-bar pin before and after you hit the reset button.
Power up tinyG, wait 5 seconds. now probe the enable bar pin, it should be high(3.3v). keep the prob on the enable bar pin and hit reset, you should
see the pin drop low for $mt seconds, then return high.
Wiring 3.3vdc to enable+ on the DM556 and the enable bar to enable- on the DM556 inverts the enable bar logic.

All this assumes that the DM556 inputs are all positive logic. You need to get me the spec sheet URL. Just copy it from browser and paste it her(the URL, not a screenshot of the image.

cmcgrath5035Moderator #12079

You should read this link(from the yellow area at top of this thread), it may help you better understand how stepper motors work,
https://synthetos.com?post_type=topic&p=6214

Also, Please start a new thread, this one is getting way too long and getting hard to navigate

akfreak #12081

in summary what I asked is are you sure the way you told me to hook the Tinyg to the Driver is correct? its neither active low or high, its a combination of both. also How is it possible to post a photo in this forum? I can post Youtube videos but nt a photo or a link. if I try to add any link the post never posts it returns a black screen.

cmcgrath5035Moderator #12082

No, I am not sure because I don't have any specific information about the DM556 you purchased, I am using some reasonable assumptions about it, specifically that the pulse, dir and enable inputs are positive logic.

Do you have access to a cloud drive service, such as Gdrive or Onedrive or DropBox (or...)
This is a rather un-modern forum tool and does not have great support for attachments.
Best way to make a picture available is to copy it to the cloud drive, copy the url to your clipboard then paste that text URL into your forum post

That is how all the URLS I have provided you are inserted. I am assuming they are working for you, is that accurate?

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