sx8851sv

I'm planning on using an arduino servo sketch to operate this servo driver. It doesnt give any other specs a side from the current and voltage ratings. I'd like some input on if it might be able to operate a 24v 20a continuous dc motor, and if theres a chance that return emf current to the PSU will destroy it. It doesnt say that it's regenerative and it looks like it comes with a huge capacitor..I figure for $60 it's worth a shot. I can't post the link, but its called sx8851sv it should be the first thing that shows up when googled.

If you're just driving a DC motor, for under $11, you can get a BTS7960B that's 27V 43A H-Bridge with lots of support for Arduino.

http://www.ebay.com/itm/131268603780

On the topic of back EMF, most power supplies will reset if you tick 'em off, and won't suffer permanent damage. But, still very annoying. With that big of a motor, you might choose to in-line a large blocking diode and some really fat caps, or even in-line a pair of car batteries.

I'm definitely a novice when it comes to motor controllers, so bear with me... I'm planning on controlling the position also, the listing is a little deceptive by calling the device a "driver", but it comes with PID adjustment through an analog potentiometer. The only reason I'm thinking of going with this one is that it seems really simple to use. Simply plug in to the arduino, and run it through a servo sketch, controlling the position with a potentiometer mounted to motor shaft. Monster Motos can't be ran through arduino servo sketches (to my knowledge), and roboclaws, and sabertooths are closed loop but are pricey, and need car batteries, kangaroos, etc...to be ran on an arduino servo code and to be powered through a PSU.

The unit I mentioned is actually quite easy to use in Arduino, and to read a pot, just use analogRead() function, voila, closed loop system.
I'd leave PID to simtools, and have the arduino code as simple and bare as possible. If you're feeling a bit bold, their are a ton of Arduino examples on how to implement PID, in case you are wanting to build a stand alone robot. (writing a PID is almost a right of passage, everybody has their own improved method. Truth be told, they all work pretty much the same).

I have a sabertooth and kangaroo, but I'm *really* liking these BTS7960B's. They are really easy to work with, very durable, and cheap enough to create lots of projects without salvaging parts from previous projects. IMHO, they are easier to work with than all the crap you have to put up with on the Kangaroo (dip switches, configuration, parsing packets, "auto tune", etc.). With the BTS7960B (and most H-Bridges), you are just concerned with speed and direction. Again, to read the pot's position, just use analogRead().

http://www.instructables.com/id/Motor-Driver-BTS7960-43A/

You're really changing my perspective on this...right now I have python extracting game data and sending datarefs to the arduino, and the arduino is sending position data to a servo (controller). In a nutshell you're saying have Simtools act as the data extractor, and using the arduino coupled with a potentiometer as my analog position reader. Simtools sends direction data directly to the "BTS7960B". I can already see a few possible advantages to what you're saying. More freedom in picking a suitable controller, maybe quicker responce and perhaps even velocity control. Does Simtools extract velocity data!? Man..I think i''m going back to the drawing boards. Again.

Another search term is "IBT-2", which is the model of this particular board (that contains two BTS7960B elements configured as an H-Bridge).
They are pretty popular in sims, and I'm sure searching this forum and youtube yields results as well. They are very easy to configure and use, and

I've gotten a number of them from the e-bay listing link I provided with no failing units.

They are also amazing for bots, because you can run 6S lipo, even fully charged they don't exceed the voltage limits. For the price and ease of use, they are hard to not give a try.

I'm seeing that the IBT-2 is rated for 43A, I havent done a lot of digging, but do you know if this is the peak current or max continuous? I'm not sure if this guy has enough juice to power a 24v 20 amp continuous motor. I've always heard peak current is three time continuous on brushed dc's.

The chips can handle bursts of much higher, particularly if active cooling is used. However, the trace widths... I wouldn't put much more than 43A continuous without pulling up the solder mask (with nail polish remover) and applying a generous layer of solder over each trace to give it more capacity.

If you are going over sustaining 43A and peaking even higher, you really will need a fan on these guys, as they will get warm, and the warmer they get, the lower their capacity gets (at 150C, it drops to 42A/59A (peak) from 43A/60A (peak) if you can keep 'em cool). Thermal shutdown can occur as low as 150C, with typical at 175C, but at those temperatures, I'd worry about the trace adhesives causing the board to fall apart.

The datasheet for the chips is here: http://www.infineon.com/dgdl/Infine...fileId=db3a304412b407950112b43945006d5d&ack=t
Then their is the boards themselves... They are Nice, but they have limits.

Before thinking I'm being unfair, the Sabertooths have the exact same issue, yet these boards are $11 ($22 for a pair of them).

Here's an important video that'll help you get the most out of your Chinese board.

The title is a bit misleading: EEVblog #317 - PCB Tinning Myth Busting
However, it goes into a cheap and easy way to raise the current capacity of an existing board, by adding solder over the traces.
Anyway, give it a look. There are a lot of boards out there that have awesome chips, and somewhat lacking board design.
This little trick will allow to get much more usage from them.

Probably a long shot, but is there a U.S. distributer of these? I have had bad experiences with aliexpress...and the ones on ebay ship through China. Which from experience can take up to a month to receive. I'd like to have one to mess with one my time off work for christmas.

Hey, and thanks for the video, I'm definitely going to give this method a shot on all my boards.

http : // amazon.com/dp/B011HF48MM

(for some reason, forum is eating link).

It ships Prime, so you could have it tomorrow if you wanted. It's not available on Prime Now, at least not here, so you can't have it Today.
From there, it's twice the cost of getting it from China, BUT, not having to wait, well, their's a lot to be said for that.

Here in the US, the original link I provided (shirmyshop88 from ebay), I received everything in under a week (from China), but can take over 10 days. And, they're under $11 each.

I don't know how well eBay or Amazon do outside the US.

If you decide to go eBay route (like I did), what I *do* know is that come February, China all but shuts down for their New Years celebration, and until that's over, getting things is a real pain, so if you are going to get them, now would be a great time. Even if you are ordering from Amazon, they will go out of stock until late February / early March.

I got my lbt-2 today, for the first time ever it's moving around via potentiometer control. Just trying to convince the gf to sit and give it a test run haha. The DC motor does put out a high pitch hum though, have you experienced this? Thanks for your help, very much appreciated, you've saved me hundreds.

The default PWM frequency is very low, definitely audible. You can go as high as 25kHz with the IBT-2 which is outside the range of human ears.

http://playground.arduino.cc/Code/PwmFrequency

Above is a link for some code that you can use to adjust the PWM frequency.

Of particular importance: The terms "TCCR0B", "TCCR1B", and "TCCR2B". If the link doesn't do what you need, type those into Google for a plethora of example code that adjusts PWM frequencies on Arduino.

Also note: 25kHz is the maximum the IBT-2 supports. I would try about 8kHz to 10kHz first to ensure the code is working before pushing it all the way to the max.

Wow, once again you solved my issue with great ease. A few more quick questions for you. If I rotate the potentiometer too quickly my power supply goes into some sort of limited power mode. Is it because the motor is drawing too much current, or is it likely that the changes in direction is causing too much regeneration? Im using a server PSU 1500w, and the motor is 500w. My second question is if there is some sort of tutorial or diagram that could help me get lbt-2 to work with simtools. Right now I'm just running a sketch that I found online that lets you control a motor w/ the Lbt and potentiometer. I'm sure at this point you're like "does this dude want me to build his rig too"? haha

Thanks again

Rapidly adjusting the pot won't cause a problem, but the motors rapidly changing directions, particularly if they have a load, can cause "back emf", and potentially freak out a server power supply (causing behavior you describe). There are many ways to solve: Diodes, Capacitors, in-line batteries, etc.

Most h-bridges are simple PWM devices (excluding intelligent ones like Sabertooth). Code written for one will work on another, as long as the PWM frequency isn't exceeded (ie. ensure you are bellow 25kHz).

Code written for Monster Moto can easily be made to work with IBT-2, with a bit of work. The IBT-2 has two current sense pins vs. 1 (R_IS & L_IS, vs. CS) (which, btw, could be used to make back emf less of a problem), and it has two enables and two PWMs (one per direction), vs. two direction pins and a single PWM, but hardly rocket science.

Bear with me man, all my knowledge of motor driving is through RC servo boards..these are my first hbridges.
Well I found an arduino sketch Racing Matt posted for 2 directional pin hbridges. I uploaded it and started with my wiring when I noticed the diagram he had showed the 2 pins for direction and an additional two pins for pwm control. I have everything wired up as shown in the diagram below with slight adjustments to the directional pins to match up to Racing Matt sketch, so my problem is I lack the additional two pins for pwm control. I went back and read through your posts about how all you need to do to make a closed loop system is to use the analog function sketch, and that other people use more elaborate sketches for "stand alone" control. I'm guessing maybe this is what Racing Matt did? Can you shed some light on this for me. And given the diagram on the bottom that i manifested what do you think would be the easiest way to get things working with simtools? The diagram on the top is the one Racing Matt has listed

I'm at work, so I can't verify this at the moment, BUT, I believe you can get by with a single PWM pin and use the two Enable pins as direction pins, rendering it pretty much identical to (half) a monster moto and even use the exact same sketch.
To control 4 motors (as with the upper graphic), you'll need 4 of the IBT-2 boards.

Arduino: | IBT-2 (board #1)
5 (pwm1) | 1 (RPWM)
4 (inA) | 3 (R_EN) (forward)
8 (inB) | 4 (L_EN) (reverse)

Arduino: | IBT-2 (board #2)
6 (pwn2) | 1 (RPWM)
7 (inA) | 3 (R_EN) (forward)
9 (inB) | 4 (L_EN) (reverse)

Arduino: | IBT-2 (board #3)
3 (pwm1) | 1 (RPWM)
2 (inA) | 3 (R_EN) (forward)
12 (inB) | 4 (L_EN) (reverse)

Arduino: | IBT-2 (board #4)
10 (pwn2) | 1 (RPWM)
11 (inA) | 3 (R_EN) (forward)
13 (inB) | 4 (L_EN) (reverse)

Obviously, for each of the IBT-2 boards, connect
7 to VCC and 8 to GND. (they are 5V parts).

The green connectors on each board: + / - go to your 24V power, and M+ / M- go to your motors.

No motion, Should I try attaching the LPWM to the RPWM on pin five?