When he sais that you have "5V" in the monitored inputs, it's because he is using something called "pull up resistors". Imagine that you have a microcontroller input waiting for a signal, can you affirm that it is 5V or 0V when you don't have anything connected to it? Well, if you are waiting for a logical "0", and if there's no signal, you would spect it to be 5V, right? But the truth is that there will be noise (electrical, thermic, or whatever) and that input will vary. You don't want to have it kind of uncertainty, so you use the pull up resistor to force that input to be in a high state (what is sometimes known as a "weak 1"). It's to say, that input will remain high until you press a button and it goes low. Now, to answer your question, in the video, he has connected the "RB0" pin (Row 1) to 5V through a pull up resistor. Remember, all the buttons aren't pressed down yet, soy they are like open circuits. That remaining connection to the button acts like an "antenna" and captures all kind of noise. Ideally, there is no current flowing between the 5V, the pull up resistor and the input "RB0" (they have the same electrical potential). Then he forces a 0 in the column "C1". He presses the first button, and the 0 will propagate from the "RB4" pin to the "RB0" one. You are putting a ground signal in "RB0". That input goes down to 0V. Also, the 5V and the pull up resistor will have a small current flowing to ground (that's why the pull up resistors have a high value). Just imagine this: if you have an input, and you're waiting for a 0, then that input should be at a 1 state. If it is already a 0, it is useless. If you don't have anything connected to that input, there will be noise. You should always know in which state it is (high or low). Only 0's and 1's, no intermediate state. I hope I was clear enough to make you understand what is happening here.
![Lp. Сердце Вселенной #60 РОЖДЕНИЕ ЛОЛОЛОШКИ [Финал] • Майнкрафт](http://i.ytimg.com/vi/YoR0pAV9FVQ/mqdefault.jpg)
so this is probably a stupid question but do you not need to use grounding pin or do the Columns act as the gnd
Very good i am studying presently
I understood thank u
Nice video and good explanation too...
Why does the node from the 5V turn 0?? How is the electricity moving?
When he sais that you have "5V" in the monitored inputs, it's because he is using something called "pull up resistors". Imagine that you have a microcontroller input waiting for a signal, can you affirm that it is 5V or 0V when you don't have anything connected to it? Well, if you are waiting for a logical "0", and if there's no signal, you would spect it to be 5V, right? But the truth is that there will be noise (electrical, thermic, or whatever) and that input will vary. You don't want to have it kind of uncertainty, so you use the pull up resistor to force that input to be in a high state (what is sometimes known as a "weak 1"). It's to say, that input will remain high until you press a button and it goes low.
Now, to answer your question, in the video, he has connected the "RB0" pin (Row 1) to 5V through a pull up resistor. Remember, all the buttons aren't pressed down yet, soy they are like open circuits. That remaining connection to the button acts like an "antenna" and captures all kind of noise. Ideally, there is no current flowing between the 5V, the pull up resistor and the input "RB0" (they have the same electrical potential). Then he forces a 0 in the column "C1". He presses the first button, and the 0 will propagate from the "RB4" pin to the "RB0" one. You are putting a ground signal in "RB0". That input goes down to 0V. Also, the 5V and the pull up resistor will have a small current flowing to ground (that's why the pull up resistors have a high value).
Just imagine this: if you have an input, and you're waiting for a 0, then that input should be at a 1 state. If it is already a 0, it is useless. If you don't have anything connected to that input, there will be noise. You should always know in which state it is (high or low). Only 0's and 1's, no intermediate state.
I hope I was clear enough to make you understand what is happening here.
This is of very useful..& I my confusions are clear.Thanks for the session
NOT A GOOD VIDEO