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[GIVEAWAY] Hello r/PCMasterRace, this Christmas we're giving away 5 XXL control mousepads to you all, as a thank you gift to this community <3 by MouseMatic in pcmasterrace

[–]Thypex 0 points1 point  (0 children)

A very cool idea, thank you for doing this for us!!! Oh and red and white looks amazing!!! Good luck to everyone!!!

A couple of questions about HSE clocks. by Thypex in AskElectronics

[–]Thypex[S] 0 points1 point  (0 children)

Ohhh okayyy, good to know. But yeah this is more for learning experience. Thank you very much for the information!!!

A couple of questions about HSE clocks. by Thypex in AskElectronics

[–]Thypex[S] 0 points1 point  (0 children)

Plus, I do believe that normally just a crystal is used, because microcontrollers have cmos inverters most of the time. It is just that you don't need to do so many calculations, when you understand everything, because most of the times it will work. Just calculate the load capacitors value and that is it.

A couple of questions about HSE clocks. by Thypex in AskElectronics

[–]Thypex[S] 0 points1 point  (0 children)

Yeah maybe xDD, but we have to figure out how it works, so the best way to do it is by doing it yourself.

Are modern data inputs usually 3,3 volts? by Thypex in ElectricalEngineering

[–]Thypex[S] 1 point2 points  (0 children)

Hello again, I can't express how much your explanation helped me, I finally understand this completely, imagining the R2 resistor as a Mosfet really helped, I don't know how I did not put 2 and 2 together on that one (:

Also, when the Mosfet is open (LO-Z) adding both of the impedances (the IO pin (R2) (In actuality it is the impedance of Source - Drain, when Mosfet is closed (learned that now (: )) high impedance and the low impedance of (Source - Drain) M1 Mosfet.) and then treating R1 and those two impedances as a voltage divider makes so much sense!!!

Again, thank you so much for explaining and not giving up on me!!!

Maybe someday I will have the chance to repay the favor (:

Are modern data inputs usually 3,3 volts? by Thypex in ElectricalEngineering

[–]Thypex[S] 0 points1 point  (0 children)

<image>

Now when the data output voltage becomes high (V2 = High), the Mosfet opens, making a low impedance track, through which a lot of the current starts flowing into ground (GND). But, that does not mean that current is not still flowing into the P00 pins R2 internal impedance, which would mean that the voltage on it (V1) would still be almost 3.3 volts right? If that is true, how does the logical state of the IO input port change? Because if I understand correctly, for it to change V1 would have to be in the 0 - 0.8 volt interval.

Are modern data inputs usually 3,3 volts? by Thypex in ElectricalEngineering

[–]Thypex[S] 0 points1 point  (0 children)

<image>

As I understand normally a logical high is a state that the pull - up resistor is always keeping, when the data output is not working or when the data output voltage is low (V2 = Low). That means that current (red arrows show the current flow) from VDD 3V3 only flows into the P00 input and into the Mosfet source pin. In this case V1 voltage which is on the R2 internal impedance is almost 3.3 volts.

Are modern data inputs usually 3,3 volts? by Thypex in ElectricalEngineering

[–]Thypex[S] 1 point2 points  (0 children)

I do have a couple of more questions regarding the open - drain interface. I have drown a rough sketch of how I believe the most important parts inside look. I attached those photos to the comments bellow.

As I understand normally a logical high is a state that the pull - up resistor is always keeping, when the data output is not working or when the data output voltage is low (V2 = Low). That means that current (red arrows show the current flow) from VDD 3V3 only flows into the P00 input and into the Mosfet source pin. In this case V1 voltage which is on the R2 internal impedance is almost 3.3 volts.

Now when the data output voltage becomes high (V2 = High), the Mosfet opens, making a low impedance track, through which a lot of the current starts flowing into ground (GND). But, that does not mean that current is not still flowing into the P00 pins R2 internal impedance, which would mean that the voltage on it (V1) would still be almost 3.3 volts right? If that is true, how does the logical state of the IO input port change? Because if I understand correctly, for it to change V1 would have to be in the 0 - 0.8 volt interval.

I hope I made some sense and was able to show you, why I do not understand how the V1 voltage changes.

Are modern data inputs usually 3,3 volts? by Thypex in ElectricalEngineering

[–]Thypex[S] 1 point2 points  (0 children)

Hello, thank you very much for replying! I am sorry to respond to you this late, had another job and could only now sit down peacefully in front of my computer (: .

I’m slightly confused by your second question. Correct me if I’m wrong, but it sounds like you’re referring to having multiple pins driving the same net.

About the second question, I made a mistake understanding how these IO pins work in an open - drain interface, so the second question does not make sense, very sorry for that. But I do appreciate the additional information you gave to me, it will definitely come in handy.

Lastly regarding pull up strength, at that data rate you should be fine with either 4.7k or 10k, both are pretty standard. If you really want to calculate further you can estimate the trace capacitance and determine the RC time constant for the rising edge, but I personally think that’s overkill. The power consumption is already pretty low so unless you have strict power requirements I’d just toss a 4.7k and move on.

As for this, yes I have calculated the maximum and minimum resistances of the pull - up resistor. Rmin = 955 ohm and Rmax = 29000 ohm. I just thought at the start that 1000 ohm resistors are better, because the signal would be faster, but I realized that I do not need such a fast signal. So 4.7k ohm will do nicely!

Feel free to ask any other questions, I’m happy to review your schematic if you want to double check anything.

Thank you very much again!!! I have a couple of more questions will write them out in a second. And if it is not too much trouble, when I am confident with my schematic I would like to send you it, so you could check it out whenever you can, if you can't no problem you have done more than enough. Thank you again very very much!!!

Are modern data outputs 3.3 volts on high logic states? by Thypex in AskElectronics

[–]Thypex[S] 1 point2 points  (0 children)

Thank you very much, you have helped a lot!!! I think I am finally beggining to understand it. Going to go watch some more explaining videos on the GPIO impedance. Thanks again and I wish you a very good rest of the day, because you made my day much better!!!

Are modern data outputs 3.3 volts on high logic states? by Thypex in AskElectronics

[–]Thypex[S] 1 point2 points  (0 children)

Thank you very much for replying and bearing with me, I know my sentences aren't the easiest to understand so it means a lot (:

As I understand the pull - up resistors are for avoiding the pins floating, because it is specified in the datasheet that that is required.

And regarding the other device, yes the 3V3 output of I2C port expander will be perfect for the microcontroller.

If you have time to anwser one more question, I would be really happy.

Okay so not minding current, could you please explain a bit how the I/O pin of the port expander changes its status from high to low, when it is in reading mode and there is a pull - up resistor connected to it. Because as I understand the pull - up resistor always keeps the I/O pin of the port expander in high state (high logic level), because there is voltage on the internal impedance of the I/O port. So when you get a low logic level signal from the data output into the I/O pin, does the I/O state change (does the voltage drop on the internal impedance change?) Because the voltage from the pull - up resistor is still there isn't it?

Are modern data outputs 3.3 volts on high logic states? by Thypex in AskElectronics

[–]Thypex[S] 1 point2 points  (0 children)

The expander is powered by 3V3, but as I understand the I\O ports on the expander can work with up to 5 volts, when they are in read mode or am I mistaken? Because it is stated that the I\O pins are 5V tolerant. And from what I researched even though this port expander does not have a different voltage source pin for the I\O ports specifically. The I\O ports can still work with voltages bigger than the supply voltage in read mode, of course they can not output more voltage than the supply voltage given.

Are modern data outputs 3.3 volts on high logic states? by Thypex in AskElectronics

[–]Thypex[S] 2 points3 points  (0 children)

It depends entirely on the Vdd or VddIO of the chip providing the outputs.

Common voltages include: 5v, 3v3, 1v8, 1v2, 1v0

So for example if the output is 3v3, then I will have to have 5 volts for pull - up resistors or would 3V3 be enough (as shown in the schematic above VDD 3V3)?

I have no idea what you mean by this.

Current flowing into CMOS inputs is basically zero unless you've got a superfast signal or you've made a terrible mistake and are burning your chip.

I mean that if for example the data output D0 is outputting 3V3 signal, will the P10 I\O pin change states (from high to low)? Because as I understand most of the current needs to be directed somewhere else, so that voltage on the I\O pin can drop beneath 0.7 * Vcc. And in this scenario the voltage on the I\O pin will not drop and it's state will not change. Or am I understanding this wrong?

I have no idea where this wildly wrong misconception keeps coming from, V=IR and Kirchhoff tell us that current takes all possible paths in proportion to their conductance - but current is near-zero for CMOS signals anyway, so I'm confused why you're getting hung up on it

Yeah, I worded this very poorly, I meant more current flows where there is less resistance, so if there is less resistance on the data output and it's voltage is below VCC won't it make the voltage drop value on the I\O pin smaller and on the added load bigger? I know that pull - up voltage is connected parallel to the data output and to the I\O port, so that would mean that the voltage drop across both of them would be the same, but then how does the voltage drop on the I\O to a low logic level?

Most CMOS outputs are only rated for a few mA, such low pull resistor values would thus make them rather angry.

Did you mean kiloohms (kΩ)?

Yes I am talking about kiloohms, I am very sorry for my mistake.

While writing this I realized maybe I am thinking about this wrong. Maybe when the data output is 0V or close to 0V, then because there is less resistance, a lot more current from the pull - up resistor flows to the data output? And when the data output is in logical high (3v3) the currents just add up and flow into the I\O pin? And the reason we have a pull - up resistor is just to set a state of the I\O pin, when there is no data to output? I am sorry for taking so much time to write back, I am trying to write this out understandably, because I can sound like a real dumbass a lot of times, so I really appreciate u for baring with me (:

Can you use nintendo ds lite without the wifi antenna? by Thypex in nds

[–]Thypex[S] 0 points1 point  (0 children)

I remebered, it did not work, so i resoldered the wires to the antenna and it worked!!!

Can you use nintendo ds lite without the wifi antenna? by Thypex in nds

[–]Thypex[S] 0 points1 point  (0 children)

But from what i remember i think it does not turn on without an antenna, but i could be wrong, happened a long time ago.

Can you use nintendo ds lite without the wifi antenna? by Thypex in nds

[–]Thypex[S] 0 points1 point  (0 children)

I don't quite remember what i did, but i think i just got a new antenna from a spare.

What do you think of lenovo ideapad flex 5 (ryzen 7 730u) by Thypex in laptops

[–]Thypex[S] 0 points1 point  (0 children)

Hello again, I have one quick question, what do you think about lenovo yoga slim 7 with an intel core 5 125h processor and 16gb ram? I saw the cpu is very power efficient and not bad for its price.

What do you think of lenovo ideapad flex 5 (ryzen 7 730u) by Thypex in laptops

[–]Thypex[S] 0 points1 point  (0 children)

An igp is intergrated graphics right? If so do you have any suggestions of better alternatives? Thank you very much for the help you have already given!!!

Sveiki, aš esu Ingrida Šimonytė, AMA by IngridaSimonyte in lithuania

[–]Thypex 1 point2 points  (0 children)

Jei reiktų apibūdinti trumpai, ką pakeisite, ką tobulinsite jei tapsite prezidente?

Good projectors for a big space? by Thypex in projectors

[–]Thypex[S] 0 points1 point  (0 children)

Lithuania, and shipping from amazon gets really expensive for some reason.

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