Cousin of OSW (Open Sim Wheel)

One question, the battery should not connect to the reverse? negative next to the capacitor and then the positive? In smc3 it is connected like this and you have first put the positive one next to the capacitor

that diagram is for the smc3 and 2 motors

this discussion is about the 'Cousin of Open Sim Wheel'

please keep the post relevant to the discussion

I am using the smc3 schema example, the scheme of the steering wheel has the input of the power supply to the ibt2 the reverse, they have put v + where v-, the polarity is reversed

ok - i see what you mean

you can reverse the direction of the wheel in the software if you need to

I have tried with an ibt2 and the buffer, I have connected the cables for the 4 ibt2, and it has not worked, I have followed the scheme I have only changed the polarity of the ibt2 as a mark that is first v-, I am also deleted the configuration of the stm32f4 even if you record it in the EPROM

Good Spot, Serves me right for copying another diagram. Yes the negative connection for the VCC is closest to the capacitor.
This is obvious when you flip over the IBT_2 as it has polarity markings. Do not connect in reverse. You can certainly connect the motor output in reverse but not VCC.

First try your connections with only one IBT_2 without the buffers. The MMos utility must also be selected as "H-Bridge" mode for the output.

Today I will try without buffer, but I explain what happens to me with the buffer, I have done a test and I have fed it to 5v, in one of the input legs I have supplied it with 5v and in the output it continued at 0v, I have measured the input legs only with 5v and gnd connected and give all 1.8v is this correct? I think my buffer is not working correctly

what is the part number of the buffers that you have?

SN7407N

Can you upload a picture of how you have connected your buffer?

I have tido sealed with silicone, I have reviewed the scheme and it is the same one that you put, this each cable in its place, I put a picture of one of the chip on top, use a buffer for the 4 ibt2, but in the silo test connect one of them, the other three connectors were not connected.
The scheme would be like yours for three ibt2 but enpalmando pin 8 and 4 to the fourth ibt2

I tried a direct iby2 and it works, but listen to the noise made by the engine, like a squeak, I have it at 16kz, there is no option, why does this happen?


Forget the chirping, raising damper to 25% is completely removed.
I have made measurements and blocking the motor to the maximum of degrees only mark 5V, I notice it loose, like 3-4nm, the stm32 takes out by p9 and p11 3V maximum, the ibt2 needs 5V to give 100% voltage, the buffer is the In charge of converting the signal from 3v to 5v? Now I have 100% mmos and I can play with an ibt2 without stopping and with the steering wheel without anchoring and on top of a glass table, something fails in all this ..

edit: I tested without a motor and when it reaches the steering lock if it gives the 12v, with the motor in lock has given 5v can it be a faulty ibt2? I have tried another one and it has reached 6v but far from the source 12.8v, is its way to cut because it passes its amps? Never take an ibt2 to the limit, I do not know how to protect

I have tried the other two ibt2 and one has reached only 4.8v and the other to a staggering 9.5v, I think it is the cut by amps of each, some will not even reach 30A and one may exceed 50A? The power supply provides 82a.
When I put the 4 ibt2 in parallel, will they provide the maximum amps?
You as tenenis the ibt2 in parallel? Directly or using a buffer? I have put a buffer but it does not work for me, I do not know what can fail.

Sounds like you may have faulty IBT or it is going into protection mode. A single IBT cannot provide the current that you should be expecting to draw when at full power.
If it is the cheap IBT_2 that you have bought you could almost expect to have some faulty ones so always buy extra. You will also need to cool the IBT as the cooling fins privided barely do anything at full current draw. Use a fan to direct air over the fins.

With the buffer it is best to test a single channel at a time without siliconing anything in place. The buffers are very simple devices, it just spits out whatever you put into it. Its purpose is just to strengthen the signal. It is best that you buy a prototyping PCB similar to these:
https://www.ebay.com.au/itm/5pcs-Pr...cing-12-611B/252144925297?hash=item3ab5023a71
What you mainly need in a prototyping PCB is the pre-linked holes so that you do not need to link holes manually with wire.

I connected directly the 4 ibt2 without buffer and it works, but they arrive 11,8v and 11,4v to the motor after the cable of 6mm and 50cm, I see a lot of voltage drop, the power supply gives 12,8v, the ibt2 I have fed them at 3.3v from the power supply. Can you explain a simple test for the buffer? If I feed 5v and I provide 5v to an input pin, should 5v come out through the output pin? If so, my buffer does not, maybe this test is not correct, but it did not work with the ibt2

Have to confrim it when I finish my build, but there is always good way to have 2 different H-Bridges to compare.

Facepalm.... I've given you the part number of an open collector buffer....

As in the picture the outputs require a pullup resistor, however you would want 5v for the pullup resistor (not 12V as shown) and a resistor value of between 1k and 5k.

Or for something very simple:

https://www.digikey.es/product-deta...L553DG/NB3L553DGOS-ND/1483114?cur=EUR&lang=en
The datasheet:
http://www.onsemi.com/pub/Collateral/NB3L553-D.PDF

One input will drive 4 outputs without all the wiring. OE (output enable) gets connected to 5v.

So you would have to buy two of these for the two PWM channels.


Sorry for the stuff around!

I'm sorry to give so much to you, my office is a bricklayer and all this costs me a lot, I think I do too much for my limited knowledge ..
So in the open collector buffer should I have put 1k resistors in the outputs? I did not know, I did not know it...
The NB3L553DG do not need any resistance? In one connects PE9 in the input and has 4 outputs for the 4 ibt2 and the other I connect to PE11 truth?
PE9 - EO , Q0,1,2,3 - IBT2 ´s ??
Now it works with the 4 directly, but they deliver 1v less than the source, I got 8.5nm of the 10nm of the motor directly to the source, I do not know if that was solved with the buffer, maybe there are other problems for not putting the buffer Until I put it on, I will not detect it ..

I have used the sn7407n with the resistors and it works, although sometimes the steering wheel makes a small movement in Windows when it should not be few times but I have noticed it. Apart from that I have not noticed any difference to having the 4 ibt2 directly to the stm32, what was the problem in not using the buffer? Did you notice without the buffer? I see it exactly the same.
By the way with the 4 ibt2 do not remove all the voltage, lose 0.6v, that is normal or should take the maximum voltage from the source?
Also the cable section loses a lot of voltage, I need 2 meters of cable to the electronics box and with 6mm I lose 1V, I will put 4 6mm cables to lose only 0.25v ..

Could have just been my STM board but it could not split the signal to multiple H-Bridge drivers. As soon as I added the buffer mine worked.
From that experience I assumed that the drive output from the STM was not good enough for multiple motor drivers.

I'm not sure what is causing the wheel to move by itself but one thing could be noise getting into the encoder wiring.
Does it move by itself during game play or just in windows?

was moved at the beginning of putting the buffer, now I have not seen it move, it was in Windows, if it happens again, remove the buffer, I worked without it too, I just see that they lose a little voltage, use 3 ibt2 and reach 10.5 and with 4 to 11.8 of the 12.5v from the source, I guess they will not be able to move the entire amperage. At the moment the tests I have done are satisfactory, good feelings and the ibt2 with the series cooler do not get very hot, I'm going to put two CPU coolers every two ibt2 and they will not heat up, the problem I have is both meters from the steering wheel to the electronics box, I had to put 5 cables of 6mm for each phase to not lose much voltage, about 0.3v with that section, any cable with little section for short that is has a voltage drop very accused