Superbly clear and informative tutorials that help me get the most out of the components I buy are a big chunk of why I turn to Pololu first for this kind of gear. I'm using that driver in a design right now and was pretty fuzzy on the current-limit/vRef relationship -- not feeling happy and confident about the design. Now, 9:02 later, I'm all over it.
This video was great for troubleshooting why one axis of my machine was losing steps: the manufacturer had set the current limit to ~20% of the rated motor current on one driver. I suspect that driver never got set from the factory. Using the screwdriver-as-a-probe technique worked great!
Video: Setting the Current Limit on Pololu Stepper Motor Driver Carriers www.pololu.com/blog/484/video-setting-the-current-limit-on-pololu-stepper-motor-driver-carriers
Really excellent information and superbly presented; thank you. Now I'm feeling guilty that I got mine from Hong Kong / eBay, even though I hadn't heard of your company before looking up this module. Heading over to your site even though I'm not doing robotics to see if there's anything I need ;-)
Thanks for the great video, just what I was looking for. However, I was using the exact same orange and black shaft screwdriver to set the current but found that the the black anodize layer on the shaft is not a good conductor. Once I removed the anodize layer it worked great.
Very useful information, but the thing about being able to set the current to 1A per coil in full step mode is an error. The power dissipated in the motor windings is the sum of the squares of the currents times the winding resistance, two coils at 70% of the limit generate as much heat as one winding at 100%. If you do the calculation for all the entries in the multistepping table in the datasheet you'll see the power dissipation is constant.
You should consult with your particular motor, but we expect that the ratings will generally apply to individual coils. You seem to be putting a lot of weight on the driver side, and the drivers are just trying to make smooth torque while microstepping. By the way, there are other drivers, such as the TB67S249FTG, that offer non-circular options where the power dissipated is not constant, and the full-step mode runs both coils at 100% instead of 71%.
The instructions in this video for calculating the current limit setting apply independent of the microstepping mode. You just need to check the product page for the A4988 to get the equation for Vref for that driver: www.pololu.com/product/1182
+The Head If you are using two identical stepper motors wired in parallel to a single stepper motor driver, you would set the current limit to approximately twice the rated current of each individual stepper motor. Please note that you should take care not to exceed the current the driver can handle.
I am using the DRV8825 driver board with a stepper motor that's rated at 1.5A. I set the VREF to 700mVolts. The stepper motor shakes volilenty without any stepping. So what can be the cause of the shaking?
There are a few possible explanations for behavior like this, but figuring out why that is happening in your specific setup will probably require some troubleshooting. RUclips comments are not a good setting for that kind of discussion, so please consider posting on our forum instead: forum.pololu.com Before you post, please review our support page which has some general troubleshooting advice and recommendations for what you should include in your post when you contact us: www.pololu.com/support
Is the motor sketch provided also the bare-minimum needed to measure the Current limit? Would connecting Reset and Sleep to +5V and Ground to ground suffice?
Hi, essmene. No, you don't need to be connected to an Arduino running the motor sketch to set the current limit. The connections you mentioned along with connecting VMOT or VDD (depending on the driver) are enough.
Can I also ask if my motor has a current rating of 1.68 A and my A4988 driver has a continuos current rating of 1.2 A can i exceed the value to get the stepper motor running at full step?
Unless you take additional steps to keep your driver cool, it will overheat if you exceed its continuous current rating of 1.2A. It is possible your stepper motor will work fine with a 1.2A current limit setting (the 1.68A is just the current you must not exceed when operating it).
I think when building a car electric motor driver three fase 120 volts, I presume also here is the need of a active current limiting, reason is when I need high rpm from a induction motor I need to do the same as with steppers, the impedance gets up on higher rpm and frequency dropping power, therefor a active current limiter allows to wind a motor for max power need lower induction and as such high current when does low rpm where frequency is lower, here a current limiter will help I presume, am I right?
Current control for a stepper motor driver is important because it allows you to use a higher supply voltage to ramp up the current quickly without exceeding the motor's limits.
In general, higher voltage allows for better stepper motor performance, so we recommend using the highest voltage that is safe and practical for your application.
You will need to supply to appropriate logic signals to control the stepper motor. How to properly connect the logic supply depends on the particular stepper motor driver carrier; you should refer to the minimal wiring diagram located on the product page for the stepper motor driver carrier you are interested in: www.pololu.com/category/120/stepper-motor-drivers If you have any more technical questions, a better place to ask them is on our forum.
Okey i have two questions. 1)If my motor is rated 1.5amp, should my curent limit max 0.75 amp since x2 it will be equal to my motor amp.Also if it is that way should i be applying 0.375 amp from my power source
Most motors' ratings are specified per phase (per coil), so if that is the case for your motor, you should also set the driver's current limit to 1.5A. Then, you would want to make sure your power supply's current limit is high enough that it does not limit how much current the driver and motor can draw (they will only draw as much as they need; the supply will not "push" current into the system). If you have any more questions, please post to our forum: forum.pololu.com/
You said unplugging the motor while under power can damage the driver or motor, is this just because of the inductive spike or is there another reason?
My DRV8834 seems faulty. When measuring the voltage across VMOT and the trimmer, the voltage stayed at 50-60mV despite turning the trimmer. Eventually the trimmer broke off after a few turns Very frustrating
Sorry to hear you are having trouble with your driver. Setting the current limit does not involve any voltage measurements relative to VMOT, so it sounds like you might be probing the wrong pins. As for the broken potentiometer, that can happen if too much force is applied with a tool that is too large. A flat 2mm screw driver generally works best. If you ordered your driver from us, please contact us directly with your order information and we can help you out with a replacement.
+Andrea Tomaghelli You can find the formula for calculating the VREF voltage for each of our stepper motor driver carriers in the "Current limiting" section of their product pages. Please note that none of our stepper motor drivers are rated for 2.5 A, so they might not be appropriate for your application. If you have any more technical questions, a better place to ask them is on our forum: forum.pololu.com
Thank you! No, we do not. We recommend getting started with the DRV8825 by reviewing it's minimal wiring diagram and the "Using the driver" section of its product page: www.pololu.com/product/2133 If how to connect to the driver is still not clear to you after looking through that, please email us directly or post to our forum for support: www.pololu.com/contact
You showed that your stepper motor had a voltage rating of 2.7v yet your power supply was delivering 12v. I understand that the power supply was powering both the board and the stepper, but shouldn't that amount of voltage have fried the motor? And how did you know to deliver 12v, I couldn't see a reference to that voltage on the product page?
Hi, Daniel. Good questions! To avoid damaging your stepper motor, you want to avoid exceeding the rated current. So as long as you set the current limit below the rated current, you will be in spec for your motor, even if the voltage exceeds the rated voltage. (The voltage rating is just the voltage at which each coil would draw the rated current based on its resistance.) Claire used 12 V because that's a common supply voltage and within the input voltage range of the DRV8825 stepper motor driver. By using a higher voltage along with active current limiting, the current is able to ramp up faster, which lets you achieve higher step rates than you could using the rated voltage.
I have the DRV8825 with the via basically on the underside. Do i solder a link, attempt to get a probe to topside avoiding the heatsink???? Probe on the screwdriver true magic.
We are glad you like the video! The driver will only step when it receives a pulse on the STEP pin, so you can leave the STEP pin on the carrier disconnected or pulled either low or high while setting the current limit.
Hello, I have a problem with my grbl CNC plotter when I run the X axis on the CNC, the y axis run and if the y axis run, then the y axis still run.mean x axis is not working in both conditions
Hi :) I have a 1.3A rated current stepper and an A4988 (Current Limit = VREF × 2.5). Does that mean I should set it to 1.3/2.5 = 0.52 v or 520mv? When measured on the vref? Also, would a DRV8834 be a better driver for this motor? Thanks!
There are different versions of the A4988 carriers, and we would need more information about your system to make a recommendation for an appropriate driver. However, RUclips comments are not an appropriate place to discuss detailed technical support questions like this. Please post your questions on our forum to continue the discussion.
We do not make the StepSticks, so we cannot comment specifically on those. For our stepper motor drivers, as long as the current limit is set appropriately, you should be able to use any voltage at or above the rated voltage of the motor, up to the maximum allowed by the driver.
The main point of the video is how to set the current limit. Measuring the current of the stepper motor is not usually necessary, but if you have further questions, our forum is a better place to have a discussion about that: forum.pololu.com
So... My 3d printer uses nema 17 -1.7a . And i just installed the drv8225 drivers, i set them in 0.6 cause was doing the calculations to don't stress my motor an reach only 1.2a (70%). But now i am confused, does that mean that it is running above the 1.2a? should i just set it to 0.85a and let the drivers deal with it?
Unless you are doing some special cooling, you should probably limit the current to 1.5A per phase (or less), so your VREF voltage should be set to 0.75V. If you have further questions, our forum is a better place for technical discussions: forum.pololu.com/
I have a huge stepper that I'm working with that draws about 1.68 A per phase and I am programming with an Arduino Uno. What's the best driver I should use? Is the one in this video sufficient? I know it says 1.5 A...
You might be able to get by with the DRV8825 carrier depending on your application, but limiting the current to 1.5A per phase will slightly lower the capabilities of your stepper motor. Instead, you might consider our brand new (released today!) MP6500 stepper motor driver carrier, which can deliver approximately 1.8A per phase continuously without additional cooling: www.pololu.com/product/2966
To get a stepper motor to hold position (i.e. be energized but not step), you can apply a constant high or low signal to the step pin, so you do not need any program. In the video the A-Star was running a program that just held the step pin high. It is easiest to get an accurate current measurement with the stepper driver in full-step mode.
What if everything is wired up as shown, powerd by an arduino Uno 5v, but neither the Potentiometer nor the test Via show any Voltage other then 0V? Also if tested with the Stepper driver example and wired 5 to 12 V on Stepper in, the motor doesen‘t work properly(high current draw but lagging movement). Is it safe to say that the Driver is damaged?
It is difficult to say without more in-depth troubleshooting. The driver could be damaged, or it might not be wired the way you think, or the way you think it should be wired might be wrong. If you have a stepper motor driver that we manufactured, please email us or post on our forum for troubleshooting assistance.
Pololu Robotics and Electronics Yes, thanks a lot for the effort! Rewatched the video and noticed the hint about the tip of the screwdriver, mine had no grip and the SLEEP and RESET pin had both to be HIGH + after pulling sleep high, you need a small 1 ms delay. I think the tutorial on your website could be a bit more explicit on the inverting logic, but maybe it’s just me. Anyways thanks a lot for your high quality driverboards and documentation!
I was wondering, wiring 2 motors is series.... would I be multiplying my current to double the value the formula gives or no?My set up.... Ramps 1.4 with 3 DVR8825 drivers(x,y,z) and 5 (2amp motors). 1000mA would be 100% per motor by my calculations and 500mA would be 50%. Would the 2 drivers running 2 motors each, then be at 2000mA and 1000mA respectively. Also, would cable length to each motor on a given driver need to be the equal... would a slight V drop affect the further motor significantly?
It is possible to use two stepper motors in series controlled by a DRV8825, but RUclips comments are not an appropriate place to discuss detailed technical support questions like this. Please post your questions on our forum to continue the discussion.
+ipadize It depends on which stepper motor driver you are using, since the equation used to set the current limit is not the same for each driver. However, this is not an appropriate place to ask that kind of question. If you want to continue checking your setup, you can start by reading our support page: www.pololu.com/support
Hello, Sipan. The DRV8825 carrier should be fine for driving that stepper motor if you do not need the full torque it is rated for, since it can only deliver about 1.5A per phase without additional cooling. You might consider our TB67S249FTG Stepper Motor Driver Carrier, since it can handle the full current your stepper motor is rated for: www.pololu.com/product/2973
Hi Claire How can I do to obtain the current value from the CD ROM stepper motors so that I can calibrate it with my A4988 Pololu driver?.These values are not even detailed in the motor parts in many cases.I `ve heard that an aprox value could be 0.20 calibration point but you will tell me if this can be done.Greetings!.
We replied to your email about the same issue. Directly contacting us over email and posting to our forum are much more appropriate than using the comment section of a RUclips video for answering technical questions.
Hello, Dario. We don't offer support in Portuguese, but it seems like you have a question about our QTR sensors (which is unrelated to this video). If you can ask your question in English, please contact us directly: www.pololu.com/contact Alternatively, one of our distributors in Brazil or Portugal might be able to help you in Portuguese: www.pololu.com/distributors#Brazil www.pololu.com/distributors#Portugal
Half step mode provides intermediate activation of the coils to give you two positions per mechanical step of your motor, so if you had a motor with 200 steps per revolution, it would take 400 half steps to make a full rotation.
We generally recommend our DRV8825 or AMIS-30543 carriers instead of the A4988 for controlling motors with currents that high. If you have additional questions, please post them on our forum: forum.pololu.com/
Hello can you tell me how you Setting the Current Limit on easy driver V44 A3967? I have stepper motor Nema 17 Rated current/ phase: 1.4A Phase resistance: 1.40hms Voltage: 2.8V supply 12v
I bought 2 motors from local robotics shop.it looks like nema 17.there was no lebeling on it when i bought it. according to a youtube video i keep the potentiometer value on 1.6 kohm on a4988 stepper motor driver. i bought today a 12 v 2 amp dc adapter.before that i used 12 v 500mA, 12v 1A, when using 500mA the motor bibrates and gives a sound. In 1 amp motor still vibrates and gives higer sound, using 12v 2 amp it again vibrates and gives ultimate sound and 4988 stepper driver's heat sink getting too hot. what should i do? please help......
Considering you do not know your motors' specifications, it is likely the current limit on the A4988 is not set appropriately for your stepper motors. However, RUclips comments are not an appropriate place to discuss detailed technical support questions like this. Please post your questions along with a detailed description about your system to our forum to continue the discussion.
Details of how the stepper motor drivers chop the current can be found in their datasheets, which you can find on the resources tab of their product pages: www.pololu.com/category/120/stepper-motor-drivers If you still have questions after referring to the datasheets, please post to our forum: forum.pololu.com/
That shirt was special! Claire probably owns the only one in the whole wide world. But you can get some other awesome Pololu shirts here: www.pololu.com/category/109/shirts
Texas Instruments state that the "continuous motor drive output current" of the DRV8825 is 2.5A and yet you show it as 1.5A, why is that? Also the DRV8825 has an internal logic power supply and so connection to the 5V of the Arduino should not be required, as a matter of fact that pin is used as a fault indication output (active low).
+Ingmar Meins See the "Power dissipation considerations" section of the item #2133 product page for an answer to your first question about the current rating. Regarding your connections comment, it sounds like you are referring to our alternative minimal wiring diagram, which is just one possible valid way to connect things. The sleep and reset pins must somehow be driven high for the driver to operate; this can be done using I/O pins or a direct connection to the Arduino's 5V output, or by driving the fault output high and connecting sleep and reset together.
What would those jumpers do? Would you prefer there only be a few possible current limit settings? By the way, you might like our new Tic T825 stepper motor controllers. They allow the current limit and other parameters to be set over USB and use higher level speed or position commands rather than a step signal: www.pololu.com/product/3130
Really clear explanation - no nonsense but covers everything relevant. I wish the other driver chips had been covered too though.
Superbly clear and informative tutorials that help me get the most out of the components I buy are a big chunk of why I turn to Pololu first for this kind of gear. I'm using that driver in a design right now and was pretty fuzzy on the current-limit/vRef relationship -- not feeling happy and confident about the design. Now, 9:02 later, I'm all over it.
Great job. The most clear tutorial I ever seen. Thanks!!
that is really a informative and clearly explained overview of the current-limit and voltage for stepper motors!
thanks!
She has a voice that is so easy to listen to.
Perfect explanation, including physics background!
The best explanation I've ever seen. Excellent. Thanks.
This video was great for troubleshooting why one axis of my machine was losing steps: the manufacturer had set the current limit to ~20% of the rated motor current on one driver. I suspect that driver never got set from the factory. Using the screwdriver-as-a-probe technique worked great!
Video: Setting the Current Limit on Pololu Stepper Motor Driver Carriers www.pololu.com/blog/484/video-setting-the-current-limit-on-pololu-stepper-motor-driver-carriers
I like this girl says!
Excellent video - clear, concise and thorough!
Great video, everything is clear now!
practically 80% from 9 minutes video was very usefull and new for me :-) thanks.
Just what I was looking for, thanks Claire. Really very helpful.
Clear, to the point. Thanks
Thanks! A good explanation. I had to see the video 3 times, and every time I learned something new :) Thanks for giving this good informative video!
Really excellent information and superbly presented; thank you. Now I'm feeling guilty that I got mine from Hong Kong / eBay, even though I hadn't heard of your company before looking up this module. Heading over to your site even though I'm not doing robotics to see if there's anything I need ;-)
Thanks for the great video, just what I was looking for. However, I was using the exact same orange and black shaft screwdriver to set the current but found that the the black anodize layer on the shaft is not a good conductor. Once I removed the anodize layer it worked great.
Perfect video! Very helpful and video very well made.
Great explanation! Thank you
Excellent. thank you. That answered many of my questions.
great presentation, thank you!!
Excellent tutorial. Thanks!
Thank you
A very well done video tutorial
Excellent! Thank you...
I love you and your musical tester !!!
Very useful information, but the thing about being able to set the current to 1A per coil in full step mode is an error. The power dissipated in the motor windings is the sum of the squares of the currents times the winding resistance, two coils at 70% of the limit generate as much heat as one winding at 100%. If you do the calculation for all the entries in the multistepping table in the datasheet you'll see the power dissipation is constant.
You should consult with your particular motor, but we expect that the ratings will generally apply to individual coils. You seem to be putting a lot of weight on the driver side, and the drivers are just trying to make smooth torque while microstepping. By the way, there are other drivers, such as the TB67S249FTG, that offer non-circular options where the power dissipated is not constant, and the full-step mode runs both coils at 100% instead of 71%.
Clearly explained!
Thanks for your video. How to calculate current limit A4988 in case 1/16 micro step. Your video is full step.
The instructions in this video for calculating the current limit setting apply independent of the microstepping mode. You just need to check the product page for the A4988 to get the equation for Vref for that driver: www.pololu.com/product/1182
Thank You for probe hint..
very well presented, thanks
thanks for helping me with my mohterr
Perfect video, thank you so much! How about if I have 2 steppers for the z-axis, does that matter in the calculation?
+The Head If you are using two identical stepper motors wired in parallel to a single stepper motor driver, you would set the current limit to approximately twice the rated current of each individual stepper motor. Please note that you should take care not to exceed the current the driver can handle.
Amazing. Thank you
I am using the DRV8825 driver board with a stepper motor that's rated at 1.5A. I set the VREF to 700mVolts. The stepper motor shakes volilenty without any stepping. So what can be the cause of the shaking?
There are a few possible explanations for behavior like this, but figuring out why that is happening in your specific setup will probably require some troubleshooting. RUclips comments are not a good setting for that kind of discussion, so please consider posting on our forum instead:
forum.pololu.com
Before you post, please review our support page which has some general troubleshooting advice and recommendations for what you should include in your post when you contact us:
www.pololu.com/support
Is the motor sketch provided also the bare-minimum needed to measure the Current limit? Would connecting Reset and Sleep to +5V and Ground to ground suffice?
Hi, essmene. No, you don't need to be connected to an Arduino running the motor sketch to set the current limit. The connections you mentioned along with connecting VMOT or VDD (depending on the driver) are enough.
Can I also ask if my motor has a current rating of 1.68 A and my A4988 driver has a continuos current rating of 1.2 A can i exceed the value to get the stepper motor running at full step?
Unless you take additional steps to keep your driver cool, it will overheat if you exceed its continuous current rating of 1.2A. It is possible your stepper motor will work fine with a 1.2A current limit setting (the 1.68A is just the current you must not exceed when operating it).
I think when building a car electric motor driver three fase 120 volts, I presume also here is the need of a active current limiting, reason is when I need high rpm from a induction motor I need to do the same as with steppers, the impedance gets up on higher rpm and frequency dropping power, therefor a active current limiter allows to wind a motor for max power need lower induction and as such high current when does low rpm where frequency is lower, here a current limiter will help I presume, am I right?
Current control for a stepper motor driver is important because it allows you to use a higher supply voltage to ramp up the current quickly without exceeding the motor's limits.
Is there any benefit from using a 24V 5A power supply vs 12V 10A? Same heat generated or any pro/con if both supplies meet the needs?
In general, higher voltage allows for better stepper motor performance, so we recommend using the highest voltage that is safe and practical for your application.
Is it necessary to only connect the motor supply? Or must the logic supply and logic signals from the MCU be present as well?
You will need to supply to appropriate logic signals to control the stepper motor. How to properly connect the logic supply depends on the particular stepper motor driver carrier; you should refer to the minimal wiring diagram located on the product page for the stepper motor driver carrier you are interested in: www.pololu.com/category/120/stepper-motor-drivers
If you have any more technical questions, a better place to ask them is on our forum.
Okey i have two questions.
1)If my motor is rated 1.5amp, should my curent limit max 0.75 amp since x2 it will be equal to my motor amp.Also if it is that way should i be applying 0.375 amp from my power source
Most motors' ratings are specified per phase (per coil), so if that is the case for your motor, you should also set the driver's current limit to 1.5A. Then, you would want to make sure your power supply's current limit is high enough that it does not limit how much current the driver and motor can draw (they will only draw as much as they need; the supply will not "push" current into the system). If you have any more questions, please post to our forum: forum.pololu.com/
Good job
hi claire,
how you measure the voltage accross the motor? which reference point are you taking ?Is it from the negative power supply for motor?
The voltage across the motor coil is measured between one side of the coil and the other side of the coil (e.g. A1 and A2 on the DRV8825 carrier).
You said unplugging the motor while under power can damage the driver or motor, is this just because of the inductive spike or is there another reason?
Justin Bell Yeah, that's the main reason; it's also generally bad practice to take apart or work on live circuits when it's not necessary.
My DRV8834 seems faulty. When measuring the voltage across VMOT and the trimmer, the voltage stayed at 50-60mV despite turning the trimmer.
Eventually the trimmer broke off after a few turns
Very frustrating
Sorry to hear you are having trouble with your driver. Setting the current limit does not involve any voltage measurements relative to VMOT, so it sounds like you might be probing the wrong pins. As for the broken potentiometer, that can happen if too much force is applied with a tool that is too large. A flat 2mm screw driver generally works best. If you ordered your driver from us, please contact us directly with your order information and we can help you out with a replacement.
hello! thanks for the video !
a question! with a supply of 24v and a motor 2.5A per phase , what the appropriate Vref ?
+Andrea Tomaghelli You can find the formula for calculating the VREF voltage for each of our stepper motor driver carriers in the "Current limiting" section of their product pages. Please note that none of our stepper motor drivers are rated for 2.5 A, so they might not be appropriate for your application.
If you have any more technical questions, a better place to ask them is on our forum:
forum.pololu.com
Nice video! Do you also have a video for wiring the drv8825 to raspberry pi and a nema8 motor?
Thank you! No, we do not. We recommend getting started with the DRV8825 by reviewing it's minimal wiring diagram and the "Using the driver" section of its product page:
www.pololu.com/product/2133
If how to connect to the driver is still not clear to you after looking through that, please email us directly or post to our forum for support:
www.pololu.com/contact
i am getting 12 v at my steppermotor coil,and at potentiometer i am getting 0.75v but at the circular hole at the 8825 i am getting 12 V
If you need technical support with a Pololu product, please contact us directly or post to our forum:
www.pololu.com/contact
forum.pololu.com/
You showed that your stepper motor had a voltage rating of 2.7v yet your power supply was delivering 12v. I understand that the power supply was powering both the board and the stepper, but shouldn't that amount of voltage have fried the motor? And how did you know to deliver 12v, I couldn't see a reference to that voltage on the product page?
Hi, Daniel.
Good questions! To avoid damaging your stepper motor, you want to avoid exceeding the rated current. So as long as you set the current limit below the rated current, you will be in spec for your motor, even if the voltage exceeds the rated voltage. (The voltage rating is just the voltage at which each coil would draw the rated current based on its resistance.)
Claire used 12 V because that's a common supply voltage and within the input voltage range of the DRV8825 stepper motor driver.
By using a higher voltage along with active current limiting, the current is able to ramp up faster, which lets you achieve higher step rates than you could using the rated voltage.
awesome!!! Thanks
My pololu8825 wont works microsteply with motors with 5 Ohm coil resistence but only work for a NEMA23 stepper which 10 Ohm resistence.Why
I have the DRV8825 with the via basically on the underside. Do i solder a link, attempt to get a probe to topside avoiding the heatsink????
Probe on the screwdriver true magic.
If you are worried about proximity to a heatsink you have installed, probing the top of the potentiometer or the screwdriver as you mentioned is fine.
Pololu Robotics and Electronics thank you.
Can these same steps be used for the A4988 black editon motor driver?
Yes, these same steps apply to the A4988 black edition.
Great video, How did you make the stepper motor not step so you could measure the full current?
We are glad you like the video!
The driver will only step when it receives a pulse on the STEP pin, so you can leave the STEP pin on the carrier disconnected or pulled either low or high while setting the current limit.
Get explanation... thank you.... is the somewhere I can get some sample Arduino code to run this?
You can find a link to a simplified version of the Arduino code used in this demo in the video description above.
Thank you for helping me with my enquiry
Hello, I have a problem with my grbl CNC plotter when I run the X axis on the CNC, the y axis run and if the y axis run, then the y axis still run.mean x axis is not working in both conditions
You might have some luck on one of the CNC forums with questions like this.
Hi :) I have a 1.3A rated current stepper and an A4988 (Current Limit = VREF × 2.5). Does that mean I should set it to 1.3/2.5 = 0.52 v or 520mv? When measured on the vref? Also, would a DRV8834 be a better driver for this motor? Thanks!
There are different versions of the A4988 carriers, and we would need more information about your system to make a recommendation for an appropriate driver. However, RUclips comments are not an appropriate place to discuss detailed technical support questions like this. Please post your questions on our forum to continue the discussion.
what is the voltage that we should give to the expansion board inorder to work for 4 stepper motor(Nema 17) (:using A4988 step stick)
We do not make the StepSticks, so we cannot comment specifically on those. For our stepper motor drivers, as long as the current limit is set appropriately, you should be able to use any voltage at or above the rated voltage of the motor, up to the maximum allowed by the driver.
@@pololu thanks, Pololu robotics and electronics
Nice video but I didn't understand how to measure the current of the stepper motor?
The main point of the video is how to set the current limit. Measuring the current of the stepper motor is not usually necessary, but if you have further questions, our forum is a better place to have a discussion about that:
forum.pololu.com
So... My 3d printer uses nema 17 -1.7a . And i just installed the drv8225 drivers, i set them in 0.6 cause was doing the calculations to don't stress my motor an reach only 1.2a (70%). But now i am confused, does that mean that it is running above the 1.2a? should i just set it to 0.85a and let the drivers deal with it?
Unless you are doing some special cooling, you should probably limit the current to 1.5A per phase (or less), so your VREF voltage should be set to 0.75V. If you have further questions, our forum is a better place for technical discussions:
forum.pololu.com/
I have a huge stepper that I'm working with that draws about 1.68 A per phase and I am programming with an Arduino Uno. What's the best driver I should use? Is the one in this video sufficient? I know it says 1.5 A...
You might be able to get by with the DRV8825 carrier depending on your application, but limiting the current to 1.5A per phase will slightly lower the capabilities of your stepper motor. Instead, you might consider our brand new (released today!) MP6500 stepper motor driver carrier, which can deliver approximately 1.8A per phase continuously without additional cooling: www.pololu.com/product/2966
Pololu Robotics and Electronics Awesome! I will definitely check that out. That's very convenient timing.
Hi , which program are you using to measure the current through one coil?(step stoped but energized?).Thanks
To get a stepper motor to hold position (i.e. be energized but not step), you can apply a constant high or low signal to the step pin, so you do not need any program. In the video the A-Star was running a program that just held the step pin high. It is easiest to get an accurate current measurement with the stepper driver in full-step mode.
Thanks you so much.Best regards
What if everything is wired up as shown, powerd by an arduino Uno 5v, but neither the Potentiometer nor the test Via show any Voltage other then 0V? Also if tested with the Stepper driver example and wired 5 to 12 V on Stepper in, the motor doesen‘t work properly(high current draw but lagging movement). Is it safe to say that the Driver is damaged?
It is difficult to say without more in-depth troubleshooting. The driver could be damaged, or it might not be wired the way you think, or the way you think it should be wired might be wrong. If you have a stepper motor driver that we manufactured, please email us or post on our forum for troubleshooting assistance.
Pololu Robotics and Electronics Yes, thanks a lot for the effort! Rewatched the video and noticed the hint about the tip of the screwdriver, mine had no grip and the SLEEP and RESET pin had both to be HIGH + after pulling sleep high, you need a small 1 ms delay. I think the tutorial on your website could be a bit more explicit on the inverting logic, but maybe it’s just me. Anyways thanks a lot for your high quality driverboards and documentation!
I was wondering, wiring 2 motors is series.... would I be multiplying my current to double the value the formula gives or no?My set up.... Ramps 1.4 with 3 DVR8825 drivers(x,y,z) and 5 (2amp motors). 1000mA would be 100% per motor by my calculations and 500mA would be 50%. Would the 2 drivers running 2 motors each, then be at 2000mA and 1000mA respectively. Also, would cable length to each motor on a given driver need to be the equal... would a slight V drop affect the further motor significantly?
It is possible to use two stepper motors in series controlled by a DRV8825, but RUclips comments are not an appropriate place to discuss detailed technical support questions like this. Please post your questions on our forum to continue the discussion.
Sorry, I didn't know... I did just sign up to the forum and posted my question in there under DRV8823 with dual motors in series.
i have 12V 0.4A Stepper Motors, i have set the VREV to 200mV, is hat correct?
+ipadize It depends on which stepper motor driver you are using, since the equation used to set the current limit is not the same for each driver. However, this is not an appropriate place to ask that kind of question. If you want to continue checking your setup, you can start by reading our support page: www.pololu.com/support
I have Stepper Motor Nema17 with 1.68A/phase can work with DRV8825 that have continuous current of 1.5A ..?
Hello, Sipan.
The DRV8825 carrier should be fine for driving that stepper motor if you do not need the full torque it is rated for, since it can only deliver about 1.5A per phase without additional cooling. You might consider our TB67S249FTG Stepper Motor Driver Carrier, since it can handle the full current your stepper motor is rated for:
www.pololu.com/product/2973
Hi Claire How can I do to obtain the current value from the CD ROM stepper motors so that I can calibrate it with my A4988 Pololu driver?.These values are not even detailed in the motor parts in many cases.I `ve heard that an aprox value could be 0.20 calibration point but you will tell me if this can be done.Greetings!.
We replied to your email about the same issue. Directly contacting us over email and posting to our forum are much more appropriate than using the comment section of a RUclips video for answering technical questions.
Thank you Claire I have received the answer into my email but unfortunatelly you haven`t been of help to my question.Thank you anyway
Ola, gostaria de comprar esse sensor e estou com dificuldades para compra devido o envio, pode ajudar: Matriz de sensor de refletância QTR-8A
?
Hello, Dario. We don't offer support in Portuguese, but it seems like you have a question about our QTR sensors (which is unrelated to this video). If you can ask your question in English, please contact us directly: www.pololu.com/contact
Alternatively, one of our distributors in Brazil or Portugal might be able to help you in Portuguese:
www.pololu.com/distributors#Brazil
www.pololu.com/distributors#Portugal
Using full-step you get one step out for each step in? What happens when you half-step?
Half step mode provides intermediate activation of the coils to give you two positions per mechanical step of your motor, so if you had a motor with 200 steps per revolution, it would take 400 half steps to make a full rotation.
So would it then move half of the rated degrees/step?
Yes, for each input pulse.
Can I control stepper motor NEMA 17 to 1.7A with A4988 driver?
We generally recommend our DRV8825 or AMIS-30543 carriers instead of the A4988 for controlling motors with currents that high. If you have additional questions, please post them on our forum: forum.pololu.com/
Hello can you tell me how you Setting the Current Limit on easy driver V44 A3967?
I have stepper motor Nema 17 Rated current/ phase: 1.4A
Phase resistance: 1.40hms
Voltage: 2.8V
supply 12v
We do not make the Easy Driver; you should ask its manufacturer for support.
vRef has a white circle??? My 8834 board is ALL WHITE?????
For the DRV8834, the VREF pin is marked with a black circle.
I bought 2 motors from local robotics shop.it looks like nema 17.there was no lebeling on it when i bought it.
according to a youtube video i keep the potentiometer value on 1.6 kohm on a4988 stepper motor driver.
i bought today a 12 v 2 amp dc adapter.before that i used 12 v 500mA, 12v 1A, when using 500mA the motor bibrates and gives a sound. In 1 amp motor still vibrates and gives higer sound, using 12v 2 amp it again vibrates and gives ultimate sound and 4988 stepper driver's heat sink getting too hot. what should i do?
please help......
Considering you do not know your motors' specifications, it is likely the current limit on the A4988 is not set appropriately for your stepper motors. However, RUclips comments are not an appropriate place to discuss detailed technical support questions like this. Please post your questions along with a detailed description about your system to our forum to continue the discussion.
forum.pololu.com/t/cnc-shield-and-a-4988-stepper-driver/12686
this is the link containing my post to your forum.
I'm wondering how 12V from Power Supply dropped to 2V at the motor?
Details of how the stepper motor drivers chop the current can be found in their datasheets, which you can find on the resources tab of their product pages: www.pololu.com/category/120/stepper-motor-drivers
If you still have questions after referring to the datasheets, please post to our forum: forum.pololu.com/
I set the current limit and something touching probe multimeter. Then the driver stopped working!
is setting per fase or motor ?
The current limit setting is based on the current per phase rating of your stepper motor.
WHERE I CAN FIND THAT SHIRT?!
That shirt was special! Claire probably owns the only one in the whole wide world. But you can get some other awesome Pololu shirts here: www.pololu.com/category/109/shirts
Texas Instruments state that the "continuous motor drive output current" of the DRV8825 is 2.5A and yet you show it as 1.5A, why is that? Also the DRV8825 has an internal logic power supply and so connection to the 5V of the Arduino should not be required, as a matter of fact that pin is used as a fault indication output (active low).
+Ingmar Meins See the "Power dissipation considerations" section of the item #2133 product page for an answer to your first question about the current rating. Regarding your connections comment, it sounds like you are referring to our alternative minimal wiring diagram, which is just one possible valid way to connect things. The sleep and reset pins must somehow be driven high for the driver to operate; this can be done using I/O pins or a direct connection to the Arduino's 5V output, or by driving the fault output high and connecting sleep and reset together.
God I swear these stupid drivers have a life of their own meant to torment and drive their users insane
Awesome video and you should move your hands/body a little bit while talking. :)
bonjour
I wish they had just 3 jumpers and we could adjust the current limit instead of messing with this shit...
What would those jumpers do? Would you prefer there only be a few possible current limit settings? By the way, you might like our new Tic T825 stepper motor controllers. They allow the current limit and other parameters to be set over USB and use higher level speed or position commands rather than a step signal:
www.pololu.com/product/3130
She looks like a female Steve Jobs