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Pololu 3730 Stepper Motor Driver Seems Unresponsive

Hello;

I am having some issues with the 3730 high power stepper motor driver, when I connect the input voltage I am not getting any response from the board.

I began by setting up the board in the configuration that is recommended on the product’s main page. Upon running the Arduino code provided in the github library, I did not get a response from the motor so I began attempting to isolate the problem.

I first ensured that the arduino was working correctly by connecting an oscilloscope to each pin and was able to confirm that the arduino was sending the proper signals.

I soon discovered that after removing everything except the input voltage, the board still does not seem to be working.

The reason that I am fairly certain of this is that after applying a 30V input voltage, the 5V reference voltage pin has no response and remains at 0V. This was one of the first things I noticed and was consistent in each isolation step that I took.

Using a pair of fine probes and referencing the datasheet for the DRV8711 I measured the input voltage to the IC and observed that the IC was receiving a proper input voltage, but still nothing on the reference pin.

Is this a dead on arrival issue or am I missing something in the datasheet

Thanks for any help you can provide

   - Bryan Desrosiers

Hello, Bryan.

We test all of these boards before they ship, so we’d like to do some additional troubleshooting try to figure out what is going on with your board.

Can you be more specific about which pin you are measuring when you refer to the “5V reference voltage pin”? Are you talking about 5V(out) or IOREF? Also, can you post some close-up pictures of both sides of the driver?

Brandon

Here is a picture of both sides of the board:


I have been measuring the voltage of the 5V(out) pin but it should not really matter if I used that or the ioref pin as they are tied together with the jumper in order to set the digital logic voltage to 5V.

Here is a screenshot of the signal from the VM pin which is how I know that the input voltage is going to the chip:


and the measurment from the V5(out) pin:


Thank you for the additional information. Unfortunately, if the 5V(out) pin is not measuring 5V, it is likely that the driver’s internal regulator was damaged somehow. Did the board ever work for you, and did you ever have that pin connected to anything else? Can you try removing the jumper and measuring the voltage at the 5V(out) pin, just to be sure?

Also, could you email us at support@pololu.com with your order information and a reference to this post?

Brandon

By the way, just to clarify, are those pictures showing how you have it connected while you are measuring the 5V(out) pin? Please note that the nSleep pin needs to be driven high to enable the device, and the 5V(out) pin will only measure 5V when it is enabled.

Could you try making sure the nSleep pin is driven high while you are measuring the 5V(out) pin?

Brandon

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Driving the nSleep pin high has fixed my problem, I should have seen this before.

Thanks for the help Brandon

-Bryan

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