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PHONE SCHEMATICS EDUCATION — Transcript · YTtoTranscript

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PHONE SCHEMATICS EDUCATION

phone schematics education · 3,465 words · 17 min read · EN-ORIG

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Below is the complete, readable transcript of PHONE SCHEMATICS EDUCATION by phone schematics education on YouTube. Read the full text, copy any part you need, or generate a transcript for any video with our free tool.

Hello everyone, how are you all? Welcome back to the another video. I hope all are you doing good and learn something new with day by day. Now in this video in this class we discuss something important something related to the basics. In my every video I told you multiple times the basics are important.

If your concepts are clear, if you understand the circuit, you can easily repair any phone. Right? So in this video, we discuss about something related to the basic call pullup, pull down, logic high, logic low. If you are already in this field past survey years and uh you are already working you already heard about

these words. If you know the schematics if you read the schematics you already know about these words up pull up pull down logic high logic low. So what is this right? How this circuit I mean to say these resistors a pull-up resistance and pull down resistors work in a circuit. If these resistors faulty missing what was

the causes what was the issue in a circuits like in a dead tree reboot or circuit behave abnormal right and what is the logic high what is logic low in this video I'll give you a full detail about all these right so if you watch this video properly without skipping end of the video I'll make Sure

the whole concept will be clear in your mind about this and you know why these are important why these are installed in a circuit let's say a resistance connecting in a IC to the ground why this resistance installed why this resistance in a heavy value if you this resistance missing what was the causes right now some

people remove the parallel resistance parallel resistance means resistance connecting with the ground point. In my every video I told you multiple times about the capacitors about the resistance what are the importance right which capacitors which resistor or which components are important for the causes. If you watch my videos properly you will know that right why these are

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important. So in this video we discuss about all these stuff. So make sure watch this video completely without skipping. I know my videos are little boring that's why there is less reach because in my videos there is are no editing uh no funky stuff on it like zoom in zoom out the other type of the

images turn out turn in my videos I'll make sure give you a complete detailed knowledge right basically my motive is about the concept concept clear in your mind right so whatever Whatever I teach you, I teach you as a way so a child can also understand. That's why there these my videos are

simple, right? So share it, subscribe it and uh comment it, like it. So YouTube can grow this channel. Uh pull up and pull down logic high. So logic low. So today today we discuss about this. Now in every electronic device especially for the digital devices let's say a laptop or mobile PCB for

example a mobile PCB. In mobile PCB there are many microcontroller or you can call a digital IC's like your CPU, your PMU and many more all are digital IC not analog. Now these digital IC for the communication with the others like a master communicate with the slaves right they use a binary language

a binary language like in this video we discuss right a topic in a language called English right so whatever I told you you can understand easily if you know the language similarly the both IC is for the communications right for the both chips use the binary language. What was the binary language called 1 0 1 0 1

1 0 0 like this. For example, if you program any IC, any chip, you can program through a behind a call in a binary language. Now the binary language work behalf of the logic high and the logic low. Like one is a logic high, zero is logic low. Clear? Let me explain you further. Clear? Now

the logic high is like on and the logic low is like off or you can call there is a voltage in voltage off. [snorts] I hope this will be clear to you here. Now how this works?

Let me give you some simple example. After this when we go to the mobile PCP section, you can easily relate this. I mean you can easily understand this like this is a any IC a microcontroller right now. This IC connected

two is switch on this side there is a 5 volt 3.3 volt 1.8 8 volt anything right. So there is a voltage for run this right when this voltage on this pin that time this IC generate the output for another work right. So basically when you press the switch right now this connected here. So 5 volt enter here

that means the logic high when the logic high here on this point I program this IC like when the logic high on this point you automatically generate the output from this point when this switch release right then there is a no voltage 0 volt then there is also the stop the output working stop.

But there is a problem here. What was the problem in a digital devices? This pin is not connected to the ground. That means when you press the switch here, right, this pin connected to the 5 volt. When you release the switch, this pin in in a floating mode, nowhere connected, nowhere connected. Call a floating mode

or you can call also the undefined. Right? Now there is a problem here. Now in around you right there are electromagnetics waves they have certain values your SMD components had uh made with the silicon and the germananium. So in a communication like 0.6 to 0.8 right from 0 volt to 0.6 to 0.8 It

assumes like a 0 volt like logic low clear and the logic high 1.5 to 5 volt call logic high. Now in between from 0.8 to 1.5 0.8 8 to 1.5 volt call undefined voltage or you can say undefined right now these undefined signals right sometime received by this floating pin because this floating pin does not

connect anywhere right it's floating in a space try to understand I'll also give you many examples right so this pin receives like a 0.5 uh 0.8 to 1.5 some one sometime higher than this. Now these like logic high works like this when you see in a DSO logic high pulse like this but the undefined voltage like this.

So when this switch does not connect here, this pin in a floating mode, right? Let me change the color. This pin in a floating mode, nowhere connected, not volt, not connected to the voltage with the logic high, not connected to the ground. So logic low. This is in a floating mode. So sometime it's receive

a fake signals undefined voltage. through undefined voltage they think there is a logic high so they generate the output voltage so through the fake signal now this problem causes damage in a PCB right this problem causes damage in a PCB let me clear you again like this is a IC right now this IC connected here

with the switch. Right? Now there is a 5 volt here. Right? When someone press this switch, the 5 volt enter here and the logic high. The 5 volt enter here. Now when the 5 volt enter here, the logic high this IC program when the logic on this pin through this pin it generate the output.

So when someone release this switch and the connection break in between the 5 volt then there is a logic low. When there is a logic low the output stopped but this pin does not connected to the ground. Now this pin on the connected to the IC side in a floating mode floating in a space. So nowhere connected

right nowhere connected. So sometime it's receive the fake signal. Fake signal means around you there are many electronic devices. It's produce the electron electromagnetic waves. Right? So sometime they receive the fake signal. When they receive the fake signal they think there is a logic high and it start the generate the output. For example, in a touch section, in a

touch section, there is a interrupt pin, right? The interrupt pin means the wake up signal for the CPU. Signal for CPU. Let's say there is a fault on their resistance. A pull-up resistance I'll show you. There is a pull-up resistance connecting to the to the LDOS's. Now if this resistance is faulty let's say and the

CPU sends the fake interrupt signal means CPU sense user want the touch activate so their touch behaves abnormal right this happen in some cases right now why this problem create because of the fake signals let me show you now let me clear you now in your SMD components right made with the silicon and the

germanmanium so in a communication line 0.7 to 0.8 this SMD communi SMD component has value for 0 volt to 0.7 to 0.8 Eight we call a logic low. That means there is a zero in a programming in a communication line and the 1.5 to 5 volt because there are low value circuits right so sometime 1.8 8 on a VCC or you

can say the VG voltage is 3.3 and the 5 volt. So 1.5 to 5 volt is called a logic high. That means when the logic high then the trigger on when the logic low from 0 volt to 0.8 volt the logic the circuit stop when the logic high the circuit start. Now in between there is a

some space from 0.8 8 to 1.5. Now these space call undefined right now when the signal works a logic high logic low when you look at in a schematics or look at in a DSO sorry it's look like this it's a proper signal right now this is a logic high this is a logic low or you

can say logic high logic low now in between there is a undefined space like this pin connecting in a floating. So it catches a fake signals like this electro electromagnetic waves. There is also a another reason because this circuit working in a low voltage so there is a high chances like a mobile

PCB maximum voltage working on VBAT like a 3.7 to 4.2 and 2 volt right. Also also when you repair there are many electronic digital devices near you. So it produces also electron magnetic waves. Clear? Now mobile PCB is a smallest PCB and many circuits in a mobile PCB there are multiple circuits graphics circuit light circuit

network circuit power circuit working closely also the mobile PCB made in a layers right so every circuit close to each other so there are high chances is to IC or you can say the microcontroller catches the fake signals. Fake signals because this plane is in a floating mode. Right? When there is a no

connection to the logic high or not connected to the ground, there is a call floating mode in a floating space. So it's connected in a fake signals. So when a fake signal for the microsconds it's connect let's say this IC assumes this IC switch in a second in a microcond in a multiple times right so

this IC think there is a logic high something a logic high when there is a catch a fake signal then it's generate the output so it's abnormal for the circuit right sometime it causes more damage in the circuit. So engineer want to d some solution for the circuit for the communication lines. So what was

the solution? Let me show you like for example similarly like this IC right there is a 5 volt here and there is a switch here right? Okay switch here. Now if you connected this pin directly to the ground the solution clear when it's connect this line connected to the ground that means there is a logic low that means a

zero logic low when this line is properly a logic low that means there is a no floating mode and no receive by the fake signal. Thought there is another problem. When this switch presses right, when the 5 volt passes here and 5 volt connected to the ground, that time your IC or you can

say your chip, microcontroller short circuit, a microcontroller or in a power line because it's directly connected to the ground. Right? So that's why we need a pull up resistor or pull down resistor because the resistor used for limit the current like for example if we use this microcontroller let's say similar here Here

here 5 volt now here switch here. Now if we connect a resistor a heavy value resistor here like I show you a 100k resistors connected in a ground pin. Right now this is a ground. So when user switch the press the 5 volt enter here because of the due to the resistor here this line does not connect

to the ground. A little current goes to the ground but this line does not directly connect it to the ground. So your circuit works safely and when user release this switch let's say in a circuit right that time due to this resistance this line working in a logic low. So there is a no fake signal here. That

means this line connected to the logic zero. Similarly the other concept here like this I see on this side connected to the ground and there is a switch here. Let's see we gives a 5 volt here on this signal. Now when the 5 volt here that means there is a logic high. When

the logic high according to the programming this IC start the working clear start the working. But when user press the switch this 5 volt directly connected to the ground. So this microcontroller or this power supply are short circuit chances increase or short circuit. Now due to this avoid this if we connect here

a resistance in between right then like in a you have seen the interrupt line right also in I2C lines I'll show you the I2C lines also then the 5 volt enter through the resistor That means there is a logic high. But when you press the switch when this line connected to the ground

right that time there is a due to this register it does not connected to the ground. So the communication properly now I'll give you some more example so you can understand in a better right we clear this. For example,

this is master. This is slave.

So like uh this is your data pin. Now the data pin

like there is a internally switch in a microcontroller and this is a voltage from internally your master like your CPU right now when CPU wants to communicate with the slave IC any slave IC like your light IC, graphic IC, your charging IC, your power IC, Then it's connected to the this point on a voltage point let's say

on their voltage point there is a 1.8 volt when it's connected to the 1.8 8 voltage let's say connected then there is a logic high when there is a logic high that means this IC sense CPU want to communicate right as I told you in the starting the ISIS digital ISIS understand the binary language

right the binary language called 1 0 1 0 1 zero logic high logic low high low high low. So before there is a low right before when the switch does not connect there is a logic low because there is a no voltage right now when the this line data line connected to the ground sorry

data line connected to the voltage line in from internally the CPU that time there is a logic high and this logic high wake up this IC it means this IC sense now CPU communicate with me the both I see ready for the communication clear. Now when there is a no need to the

communication then there is this pin again in a floating mode right that time it's received the fake signals as I told you like this a fake signals through fake signals for the microsconds if it's convert in a logic high again and it's generate the output may Maybe it causes something crucial. Get it? To avoid

this, right? If we connect here ground, right? Internally, this pin connected to the ground that means there is a logic low. When switch trigger to the voltage line your CPU internally short or maybe this IC also short now I hope you get it for solution this let me erase this now that time let's say we connect here

a resistance to the ground a heavy value resistance let's say 100k or you can call a 10k to 100k resistance connected to the ground. So what happened this line is in a logic low when it's connected to the VCC or you can say the 1.8 8 voltage here that time it's converted in logic high

due to this resistance a little current passes to the ground but this line does not connected to the ground right so this IC sends logic high and it's start the working when this switch release. Now when this switch release due to this resistance right it does not connected properly to the ground but it's

retaining in a logic low. So this pin not in a floating mode it's connecting to the logic low to avoid fake signals. I hope this will clear to you. Now in another example this pin internally CPU had many common ground. Right? Now look at this example. This is a vice versa example. Right? Now in this

this pin we call a floating pin nearby the ground pin right now CPU had a multiple grounds right now let's say CPU internally gives a voltage properly to this line on this line the logic high permanently now when the logic high that means your this IC since GPU wants to communicate so it's this IC will be a

ready form and it generate the output means the communication ation start between both IC's and whatever the whatever the command from the CPU it's operate right now when CPU does not need to communicate like in a sleep mode when CPU connect this line to the ground like this what happen this line become a

logic low but if there is a 1.8 8 voltage for the logic high. This line also goes to the ground. Right? And before due to this your microcontroller or you can say your CPU or slave are short. To avoid this from a PMU a line come out on this line there is a resistance

connected let's say a 10k resistance on 1.8 date value. Now this line is a logic high. When this line is a logic high, the slave communicate with this master. When this line connected to the ground, due to this line, due to this resistance, this voltage does not directly connected to the ground. So both pin had a value. It

means there is a no otherwise this pin on a floating mode. Now this pin had a 1.8 8 voltage from the PMU right not in a floating mode when there is a no logic that means when there is a logic high but when there is it's connecting to the zero on this pin it's

a properly ground a logic low means this pin so it does not receive any fake signal I hope you get my point so that's how the logic high logic low working and the pull-up register. Now if you want to be a more information or more knowledge about this topic or about other topics in a deep detail you

can join our online classes. In our online classes in our online courses we provide a deep detail. Now this classes also in a minimum prices and is it give you a best result. So if you think I'm the right teacher for you and if you want to be upgrade yourself so this is a

opportunity for you. Join our online classes and upgrade your level right now. We will meet you in the next video. Thank you so much next video. Love you all. Bye-bye.