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<set_> ds2: So, if the am335x GPIO pins go HIGH/LOW at 2.65v, what is the definitive cure in the form of math? I mean, say...
<set_> my op-amp, and no to the switch for now of the BJT, needs to be accepting of 4.5v at least for the "OPTO" switch to turn on the driver.
<set_> If you ever get around to the build of it all, please let me know. Struggling with simplicity and simplification over here (and at the same time)!
<set_> Let me get a circuit on photo.
<set_> Please hold.
<set_> This will take a lifetime. Forgive me. I need to brush up.
<set_> Okay!
<set_> I think I made sense out of what I "accomplished..."
<set_> It is some online repo of sorts with a GUI.
<set_> If that is okay...okay. If not, okay.
<set_> I thought I would share.
<set_> and the second rail on the lower section is the 2.65v which I think needs amplification now.
<set_> I will come up with something...
<set_> sorry. That is wrong. I did it incorrectly.
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<set_> There is a driver between the motor and op-amp.
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<set_> So, 3.3v is actually 2.65v when the GPIO goes HIGH and my divider circuit is bunk because it causes current of 1.65v. Blah. I am pushing current at 1.0v. Ha.
<set_> That does nothing to this driver.
<set_> So, this was my best guess until knowing it. "I hold the GPIO HIGH" while the motor moves and then change direction.
<set_> Man, time flies.
<set_> I should have measured my divs.
<set_> Basically, I am trying to make sure the board does not die while attempting glory. A lost pin or two is not big deal (sort of) but oh.
<lucascastro> measure the voltage without any circuit biased
<set_> !
<set_> so, apply the measurement without the op-amp or the voltage divider is what you are saying or just the voltage divider needs to be not applied?
<set_> I thought the GPIO when HIGH was 2.65v of current...
<set_> rising...sorry.
<set_> Not HIGH, rising.
<lucascastro> is not that god drive current though GPIO
<lucascastro> But measure the voltage without any circuit.
<lucascastro> op-amp or voltage divider.
<set_> lucascastro: I am driving two GPIO pins and a 5v pin from the BBG to the op-amp to the driver...
<set_> I have a voltage divider on each GPIO to sway away from EMI.
<lucascastro> I don't know about the BBG I only own BBB, so you can read the spec of BBG and look for the maximum current through the board/GPIO
<set_> am335x
<lucascastro> calculate your circuit how current will drive.
<set_> It has the same am335x.
<set_> Okay...I will calculate how the current drives.
<set_> I guess I need to find the BBB now.
<set_> Maybe this board is different.
<set_> So, one end to the other and then end it. Got it. Okay.
<lucascastro> op-amp is good because you can use external power-supply.
<set_> 3.3v (2.65v rising) GPIO to voltage divider (1000k and 10000k equal 1.65v of current when HIGH) and then partially GND and then to op-amp (inverting or non-inverting (my choice)). Like this?
<lucascastro> R (1M and 10M) ?
<set_> 3.3v (GPIO) goes to op-amp(inverting) and the ... No.
<set_> k
<set_> Oh.
<set_> 1k 10k
<set_> Sorry.
<set_> Blah.
<set_> So, then GPIO goes to op-amp and then GPIO to voltag divider goes to op-amp and GND.
<lucascastro> ap-omp parallel to voltage divider?
<set_> On my LM358N, it states inverting and non-inverting but yes.
<set_> I have two outputs on the op-amp.
<lucascastro> if parallel to voltage divider, maybe depends how your op-amp is setup, boards ends up fed current through op-amp.
<set_> So, the GPIO to voltage divider to op-amp on one pin of the op-amp.
<set_> Right.
<set_> That is what I was afraid of now.
<set_> Because of the voltage divider, it never reaches above 1.65v.
<lucascastro> are you going to driver motor? Why not use the external power-supply over the op-amp?
<set_> yes.
<set_> I was...but I have a driver.
<set_> The driver is for a two-phase motor.
<set_> I have two GPIO pins controlling dir/step and then a 5v supply on an optocoupler type connection to the driver.
<set_> So, my op-amp provides (supposedly) enough current and amperage via the GPIO pins on the am335x supported BBG to make the motor in an enabled/disabled state, step/dir, and to get recognized by the BBG.
<set_> The driver is supposed to do the rest...
<lucascastro> My guess, if you have a circuit driver, it supposed just a voltage signal, not really driver the current, the current go through the 5v that supplied the driver.
<set_> Right. it is a driver for 5v supplies.
<set_> Oh.
<set_> I just understood what you typed.
<set_> Dang it, okay. But, the step/dir pins need 4.5v minimum.
<lucascastro> maybe I'm not that clear.
<set_> I think. Dang it. Let me double check.
<set_> I got you.
<lucascastro> What's the meaning of "Dang it"?
<set_> Darn
<set_> Or maybe... I mean something like I did not check that already and am having a epiphany.
<set_> This is what the driver datasheet says: Pulse signal: Pulse active at rising edge; 4-5V when PUL-HIGH, 0-0.5VwhenPUL-LOW.Minimal pulse width of 2.5μs. Add a resistor for current-limiting at +12Vor +24Vinput logicvoltage (1K for +12V, 2k for +24V). The same as DIR and ENA signals.
<set_> ...
<set_> So, I was trying to amplify the voltage to suit my needs.
<set_> I got to amplification without movement which caused the heat.
<lucascastro> So, seems like you need just the signal 4-5v over BBG. The resistance and current control is though the power supply biased to the driver. I'm not english native, but it was what I got.
<set_> Okay.
<set_> No issue about your English. I was not born in England either.
<lucascastro> The driver is powered with 12V and 1K
<set_> Yea...I saw that sir.
<lucascastro> Let me know if it worked.
<set_> I usually put in about 12.4v at 1.2A.
<set_> That is to power the driver. Then, to supply the Rise of the GPIO...
<set_> Got you again.
<lucascastro> That's for the driver that control the motor.
<set_> Oh. so, the motor accepts 4 to 5v.
<set_> Aw.
<lucascastro> If I'm not wrong, the driver has its power-supply
<lucascastro> not?
<set_> Yes. I supply it with power.
<lucascastro> The driver accept a signal at some pins.
<set_> It is a dead driver without PWR and GND which I supply from a bench supply.
<set_> Yes.
<lucascastro> that pins is connect to the BBG
<set_> yes.
<lucascastro> So, it was be working
<set_> Nope.
<lucascastro> I really don't no way not.
<set_> The logic signal current is at 7mA.
<set_> That logic signal current is at 7mA to the driver...
<set_> nominal/typical is 10mA.
<set_> hence, my rendition of odd circuits to supply the demand.
<lucascastro> if the drivers has a FET/MOSFET over the signal pins, it would tried direct biased.
<set_> Okay.
<lucascastro> But.
<set_> But?
<lucascastro> If you have op-amp, you can use a 5v for op-amp supply
<set_> Oh.
<set_> I can use 3.3v for these op-amps.
<set_> I can try 5v, I guess.
<lucascastro> but the driver as you mentioned it's require 4-5v
<lucascastro> for signal
* jkridner waves to ds2 ... nice to see you active in here.
<lucascastro> then it's required you supply your op-amp though 5v external supply.
<set_> lucascastro: okay.
<set_> I will attempt that idea.
<set_> Is there a way to control the GPIO pins so that I do not harm the processor on board?
<lucascastro> so when you get 5v at out of op-amp, it should work.
<set_> Aw!
<set_> Okay.
<lucascastro> yep.
<set_> i will test until my heart is content!
<lucascastro> almost use a mosfet as turn on/off button, but you can set the op-amp for that.
<set_> Right.
<lucascastro> The op-amp it's a really good way for that shifting.
<set_> That is what I thought. It accepts two "unbiased" pins from the BBG and outputs one signal.
<set_> But, I added bias for no reason (pin protection).
<lucascastro> that I look at op-amp datasheet
<lucascastro> really common for the external power
<set_> Okay. If you get bored, look here: LM358N from TI.
<set_> It can go as low as 3v.
<lucascastro> Okay, I had wrote wrong, the idea was for you take a look, but I'm doing
<set_> No...do not. No issue.
<set_> 3v minimum.
<lucascastro> So, it's really common, you have the gnd(4) and Vcc(8) for external supply.
<set_> Right.
<lucascastro> so you put the 5v there you'll get 5V at output
<set_> Right, that was the issue...
<set_> I was trying to create the "more-complicated" level shifter with voltage and amperage amplification.
<lucascastro> hadn't you fed the op-amp?
<set_> Yes.
<set_> 3.3v
<lucascastro> so you fed with 3.3v. you will just get maximum 3.3v at output.
<set_> Are you sure...?
<lucascastro> yes.
<set_> Okay.
<set_> I will test it.
<lucascastro> The Vcc is not the BBG voltage, it's a external voltage.
<set_> Oh.
<set_> I was not aware of this fact.
<set_> I will review the datasheet again. Thank you.
<lucascastro> At the input you'll need BBG gnd and GPIO pins for signaling .
<set_> Right.
<set_> So, I need to worry about EMI now with the circuit if things go the wrong way.
<lucascastro> And that it's not going damage your BBG because the required current comes through external power
<set_> Hmm. Are you sure?
<lucascastro> Yes,
<set_> I will test it. Thank you.
<lucascastro> That's why the ap-omp is really good for that propose.
<set_> I thought the 5v has to come from the BBG and to use a level shifter of sorts so that the two biased voltages do not intersect?
<set_> Thank you. I was dead wrong.
<set_> Okay! Whelp, it is 10:00 in three minutes and I need rest. Peace to you, brother.
<set_> Testing will ensue.
<lucascastro> Okay
* set_ says lucascastro saves the year of blabber mouth set_!
<lucascastro> If you look at the op-amp diagram, all the current comes from the vcc
<set_> Right...
<set_> I thought that was the BBG and not a 5v supply.
<set_> Sir, where would I get a 5v supply?
<set_> I mean...I would have loved if the BBG or newer boards had the built in GND for 5v.
<set_> Then, one could test their circuits with 3.3v and do some neat work.
<lucascastro> you can use other external for testing, and after get it working, you make divider and share with the driver board.
<set_> Oh.
<set_> Okay.
<lucascastro> But it's not good driver current through uc
<set_> Right. YOu are right.
<set_> It is not enough.
<lucascastro> I looked for blabber mouth
<set_> Ha.
<lucascastro> is it a city?
<set_> No.
<lucascastro> I found this
<lucascastro> hard rock.
<set_> Blabber Mouth = A person that tells the way he/she sees it.
<set_> Nope.
<set_> But non-stop!
* set_ says too much and they call my a blabbermouth set_.
<lucascastro> got it
<set_> Okay.
<lucascastro> just get it working and it'll be fine.
<set_> Okay.
<set_> It is going to be a nice one...not the most complicated but odd stuff happens each time unless I am correct (hardly ever).
<lucascastro> Hope the best result.
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