TB6612FNG Dual Motor Driver Carrier problem

It seems disingenuous of you to link to a thread where the person outright states “thus, there is nothing wrong with the drivers or motos. It must be something with my circuit.” and use it as an example of our drivers failing.

Using VCC from the Arduino to drive a motor is bad form, but note that the Arduino’s VCC can deliver close to 800 mA. You were using VCC from the FTDI adapter, which can only deliver a few tens of mA and is absolutely not meant for this kind of application. Can you link to anyone else who has tried to do this and had success?

And you still haven’t addressed what you think is different between our carrier board and the Sparkfun version. You seem to be using your one negative experience as proof that our version must be inferior, and that is not logically valid.

- Ben

You quote his conclusion but not his logic. He only tested the motors and assumed the drivers were good because it is mind boggling to think that he could try that many different ones and have them all fail.

Are you saying that the logical conclusion is that all four boards are defective? As I’ve said, of the thousands of these carrier boards we’ve sold, you’re the first person I know of who’s contacted us about breaking one, so the odds of this customer getting four defective boards would exceptionally low.

I know you want to be able to blame your troubles on a bad product and you’re looking for support for this position, but the justification just isn’t out there. This is a good motor driver made by a very respectable company (Toshiba). Our board is just a breakout board that makes the TB6612 easier for hobbyists to use. Aside from our board being more compact and having reverse voltage protection on VMOT, our board is the same as Sparkfun’s. If you look at the schematic, you can see there isn’t much to it:

All we’ve added is a reverse voltage pretection MOSFET and some VCC and VMOT power capacitors.

Can you even venture a wildly speculative guess as to what in the above schematic would make our board more succeptible to failure than Sparkfun’s? For that matter, can you find any way to criticize this product without having it be a direct criticism of Toshiba and their motor driver IC?

- Ben

Just for kicks, I went back and looked in detail at the thread you linked. The reasons for his problems are obvious if you look at the pictures he posted: he didn’t solder the header pins to the motor driver! This is absolutely not an example of having a motor driver “fail”; there is no reason to expect the driver to work while just resting on the header pins.

I’m sure there are other posts like this from people new to electronics having trouble using motor drivers (both ours and Sparkfun’s), but I’m willing to bet they can all be explained by things like bad code (it’s not doing what you think it’s doing), bad connections (wrong voltages on pins, bad solder joints, lack of common ground, lack of appropriate external pull-ups/downs, etc), or bad power supplies.

- Ben

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This doesn’t have much to do with the original topic, but what a great picture. Yeah, I know I’m thinking out loud about a market I know nothing about in front of people who do.

“There is little more dangerous than a programmer with a soldering iron or a hardware engineer with a C++ compiler.”

The Arduino ecosystem seems to be drawing in masses of people who wouldn’t have thought themselves able to make software interact with the real world, or that it was beyond their available level of effort. Back on USENET, veterans used to dread September because the start of university would bring a fresh crop of clueless new people each year who took ages to housebreak. When AOL added USENET access, it brought in a huge, constant flood of clueless people. The term that stuck was “Eternal September”. (Later we called this “the democratization of the Web”, but I’m getting off on another tangent.) (Edit: apparently so long ago I forgot whether it was perpetual or eternal September.)

Looking around the Arduino message boards, I see a lot of people lacking skills, theory, or other background knowledge that could previously be assumed if people were interfacing ICs to microprocessors. I’m one of them; I have a folk theory of voltage in my head, and sometimes I think about watts, but current is not something I have an intuition for (which means BJTs are magic.) It’s surprising how much you can do and get away with in Arduino-land with just a voltage mental model plus “put a current-limiting resistor here” which is stressed in detail as part of the ubiquitous initial LED control project. Probably “can’t hurt to add decoupling caps” is in the heuristics too.

You can also do a lot in Arduino-land without soldering, or just with the minimal ability to solder two leads twisted together. When I see a PCB lying on header pins on a solderless breadboard (great catch), I think “this person has probably never done PCB soldering.” Or maybe they have and it was a disaster and are trying to avoid it. Or they don’t know everything doesn’t connect as easily as a solderless breadboard/female header. (But Fritzing, bless its heart, makes it look that way.) They’ll get practice soldering on perfboard eventually. Using a purchased breakout board seems to be the only part of their getting off the ground that (should have) required PCB soldering.

Everybody and their brother seem to have their own “just plug and play” 5v/signal/ground module interfacing system for microcontrollers, but solderless breadboard is the only real common interface. A quick scan of the tutorials by the usual suspects shows plenty of “how to assemble a kit which incidentally includes headers” but all of the “how to use a PCB-based module on a breadboard” have a step ~7 consisting solely of “solder headers on”. This is the only time you’d need to solder in basic Arduino-land (and not totally trivial, given the pictures in sparkfun.com/tutorials/114 ). Maybe I’m overthinking and this is just solvable with a simple end-to-end project doc that says in large friendly letters “DON’T PANIC”.

In any case the market for prototyping parts now includes people who lack confidence in PCB soldering. They never did the LED christmas tree. It’s not clear this is a great submarket to sell into, but it’s out there. Some vendor of building-block breakout boards might try selling a few with optional soldered-on headers. (Maybe it already was tried and failed.) There are some people (maaaaybe me) who would be willing to pay for the increased fabrication cost plus the increase in shipping for packing a non-flat component, if the components came solderless breadboard ready. It’s like the next step above kit to assembled. What the cost would be (and the SKU overhead) versus demand price is beyond me. Probably most hobbyists will pick up through-hole PCB soldering pretty quickly, but it’s a leap especially with $10 irons. (Never mind that you could pay for a real soldering station with the savings from doing such easy assembly locally. But you could learn crimping too.)

Off in the PC modding world, people seem to be happy to pay for somebody else to do heatshrink on cables even though header-flavored Molex pin extraction is hardly rocket surgery. frozencpu.com/products/7639/ … able_.html is some kind of extreme. Not sure that level of…whatever it is…exists anywhere else.

I lack theoretical understanding of circuits, but solder skills I have. I can cookbook with the best of them. The trouble (IMO) is that with things like motor controllers, voltage regulators and shifters (probably no coincidence that those are the parts I have trouble with) you are dealing with inputs that are not TTL level and on’t come from a specific source. It is easy to suspect that they were out of range. OTOH, those types of boards are far less likely to have been fully tested because of the wide range of inputs they can take. The hard part is that I have to rely on info from others to get me through those parts and when engineering colleagues/acquaintances tell me that what I am being told by the vendor doesn’t make sense, I get really frustrated.

It sounds like you are still trying to deny your responsibility for the problems you’re having. To bring up the egg analogy again, what you are doing is the equivalent of dropping the egg, complaining that it broke, and then saying it was probably broken before you dropped it.

By the way, parts like these are tested quite a bit more than you probably realize. When a part has some rating, such as a 6V max, combinations of tests and design ensure that the part does indeed meet that specification, and in many cases, will substantially exceed it. That margin might in turn allow you to get away with poor practices sometimes, but other times, you’ll be less lucky.

- Jan

Can you help me understand why a low PWM is more stressing on the power supply? Is it because the off time is longer so the decelerating duration is longer?


With a low-frequency PWM, there is a long off time during which a high current can build up in the braking circuit. That current then gets switched back into the power supply during the on time, potentially causing a dangerous rise in voltage. At a higher frequency, the current through the motor will hopefully stay closer to its average value, so that you would not see this kind of problem.


RTFM arbarnhart! :wink:

Tie VMOT to Vcc at your own risk.

If you are reading this thread because you have a similar setup and are having problems I recommend you ignore everything arbarnhart says. He is too lost and will only confuse you. There is nothing wrong with his board - at least there wasn’t. Maybe he got lucky once he separates Vmot from the rest of his circuit it will all work again. The example he referenced didn’t work for the same reason. Motor noise on his controller.

I wanted a constant regulated voltage into my motor so I initially ran a 7.4V lipo to a 5V switching regulator and used the 5Vcc output of the regulator to power an arduino (via arduino 5V pin), and both TB6612 Vmot and TB6612 Vcc. My motor ran fine forwards and backwards in this configuration. It was a false confidence.

I swapped out the Arduino Uno for the Baby-O. When the motor tried to start up, the current surged to the motor and jerked my Vcc around so much it reset the microcontroller every time I commanded AIN1 or AIN2 HIGH. When I separated Vmot from my regulated bus and tied it directly to the battery, with the power supply between the motor and 5Vcc it runs perfect. No residual damage apparent in the Baby-O or the TB6612.

After some thought I realized even if it did work to tie Vmot to the same bus as the logic, (despite a deliberate design that separates them) do you really want to put all that noise on your power bus? it will likely change the performance of your analog sensors and may permanently damage other devices used in your circuit.