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Adafruit motor shield v2 - no voltage to m1-m4?
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Adafruit motor shield v2 - no voltage to m1-m4?

by LukeMatkovic on Thu Apr 19, 2018 9:09 pm

Hello.

I am currently using:
Arduino Uno
Adafruit Motor Shield v2 (or whatever the most recent version is)
LIS3DH accelerometer
NeveRest Classic 60 Gearmotor (am-3103)
USB connection to laptop + 12V power source (from myRio, happens to work here quite nicely)

After many hours of tinkering, soldering, and re-soldering, I've managed to have the accelerometer work correctly while mounted on a copper PCB, which was then mounted on the motor board. Prior to mounting the accelerometer, I had the motor (and a previous motor we scrapped because the encoder was too precise and output pulses at too high a rate, so that some were missed by the uno) work fine when plugged into M1. Additionally, the encoder power and ground were plugged into 5V and GND, respectively, and the third cable that is used for the interrupt to count the pulses was plugged into D02. This setup worked without a hitch. However, after setting up the accelerometer and rewiring the motor like it was before, the motor ports (all 4 of them, M1-M4) appear to have no voltage. Continuity and DC voltage tests were conducted on pretty much every pin combination to see if any wires had been "crossed" via soldering or where the voltage was "leaking." However, this proved unsuccessful and now I have motor shield that has 4 motor ports that each read ~0.03mV while they should be reading ~12V.

Any advice would be very greatly appreciated, as tomorrow is essentially the final day I can solder.

LukeMatkovic
 
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Re: Adafruit motor shield v2 - no voltage to m1-m4?

by franklin97355 on Thu Apr 19, 2018 11:20 pm

Can you post up pictures of the shield and tour connections?

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Re: Adafruit motor shield v2 - no voltage to m1-m4?

by LukeMatkovic on Fri Apr 20, 2018 10:20 am

Here are some of the pictures. The connections that look spotty were checked with a voltmeter and they're working as desired.
Attachments
ada3.jpg
ada3.jpg (75.94 KiB) Viewed 171 times
ada2.jpg
ada2.jpg (105.83 KiB) Viewed 171 times
ada1.jpg
ada1.jpg (107.83 KiB) Viewed 171 times

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Re: Adafruit motor shield v2 - no voltage to m1-m4?

by LukeMatkovic on Fri Apr 20, 2018 10:21 am

More pictures.
Attachments
ada5.jpg
ada5.jpg (74.39 KiB) Viewed 171 times
ada4.jpg
ada4.jpg (91.58 KiB) Viewed 171 times

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Re: Adafruit motor shield v2 - no voltage to m1-m4?

by adafruit_support_bill on Fri Apr 20, 2018 10:32 am

The connections that look spotty were checked with a voltmeter and they're working as desired.

That is not really a valid test. Marginal solder joints often become conductive when you poke them with a meter probe.

But the main problem is most likely the motor itself. Those AndyMark motor have a stall current of 11.5A and typical operating currents well above the 1.2A rating of the shield. Since startup is essentially a 'stall' condition, starting the motor will briefly pull nearly 4 times the peak rating of the TB6612 drivers on the shield. They are not likely to have survived that.

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Re: Adafruit motor shield v2 - no voltage to m1-m4?

by LukeMatkovic on Fri Apr 20, 2018 10:58 am

adafruit_support_bill wrote:That is not really a valid test. Marginal solder joints often become conductive when you poke them with a meter probe.


To elaborate a bit, pins before the joint were tested with those after to determine continuity. Additionally, adjacent (both directly adjacent and those that had multiple pins in between) pins were tested to make sure there was no continuity (outside of ground).

adafruit_support_bill wrote:But the main problem is most likely the motor itself. Those AndyMark motor have a stall current of 11.5A and typical operating currents well above the 1.2A rating of the shield. Since startup is essentially a 'stall' condition, starting the motor will briefly pull nearly 4 times the peak rating of the TB6612 drivers on the shield. They are not likely to have survived that.


This would make the most sense. My group ordered another motor shield and we'll be sure to use the other motor we had that had a smaller stall current, so it shouldn't damage the driver. Thank you!

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Re: Adafruit motor shield v2 - no voltage to m1-m4?

by LukeMatkovic on Fri Apr 20, 2018 12:44 pm

https://www.dfrobot.com/wiki/index.php/12V_DC_Motor_251rpm_w/Encoder_(SKU:_FIT0186)

This is the motor we were using prior to switching to the AndyMark motor. When we ran it with 5V (USB power), it moved fast enough for our needs. If stall current is proportional to the voltage, then the stall current for this one should be just under 3A. I believe the operating current should remain within the 1.2A limit for the motor shield. Do you think this would be fine to run with the motor shield?
Last edited by adafruit_support_bill on Fri Apr 20, 2018 1:21 pm, edited 1 time in total.
Reason: fixed link

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Re: Adafruit motor shield v2 - no voltage to m1-m4?

by adafruit_support_bill on Fri Apr 20, 2018 1:09 pm

The link doesn't seem to be working. But the stall current is essentially the supply voltage divided by the winding resistance. So it should be proportional to the supply voltage.

Normal operating currents are harder to characterize. The "no load" current is not a particularly useful number, because any real application is going to have some load.

The "Peak" rating for a driver typically refers to momentary peaks such as those encountered during motor startup. These should not exceed a few milliseconds.

The Continuous rating is the current level that the driver can handle on a continuous basis. In the case of the TB6612, that is 1.2A.

I'd try running the motors under load at 5v with a multimeter in the loop to measure the current.

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Re: Adafruit motor shield v2 - no voltage to m1-m4?

by LukeMatkovic on Fri Apr 20, 2018 1:13 pm

The link should include the ")" at the end but it got cut off. Thank you, I'll try that.

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