The problem I have with this remedy or method is that it's polled I/O,,,,, it ties up my micro and even if I allowed it, a substantial interrupt service routine would cause missed keystrokes. Wouldn't an interrupt based solution be better ?
Great video, Dr. Tom Lombardo. AND, the link to your Google docs is working (4/16/2019). The last line in your keyinterfacing pdf states "The diodes protect the circuit in case someone presses 2 keys in the same row but different columns at the same time". Great advice! Just out of curiosity, WOULD THE DIODES BE NEEDED IF 2 KEYS WERE PRESSED IN THE SAME COLUMN?
Thanks for the kind words, Ron. 2 keys pressed in the same column would not cause an electrical problem. The idea is to avoid shorting two columns together because the columns are outputs; if one is sending out a 1 while the other sends out a 0, you'd be shorting Vcc to ground by pressing keys in both columns. The diode ensures that current can't flow out of a column when it outputs a 1.
I fixed the link to the handouts. Sorry about that!
drive.google.com/open?id=1OSH5xolX6hEAUYEoXhaRUl4dmmvYUT8G
Thankyou very much for this vid, you're clearing up 3 days worth of confusion with this knowledge. A true diamond in the rough. 4/10/2022
You just gained me 10marks more in my exams!
Thank you so very much!
thank you for this simple yet awesome analysis!!
Can I applied these same principles to an arduino uno project? I need to design and make a 30 keypad with an arduino uno.
The problem I have with this remedy or method is that it's polled I/O,,,,, it ties up my micro and even if I allowed it, a substantial interrupt service routine would cause missed keystrokes. Wouldn't an interrupt based solution be better ?
We need this type of work engineer which make matrix keypads
Great video, Dr. Tom Lombardo. AND, the link to your Google docs is working (4/16/2019). The last line in your keyinterfacing pdf states "The diodes protect the circuit in case someone presses 2 keys in the same row but different columns at the same time". Great advice! Just out of curiosity, WOULD THE DIODES BE NEEDED IF 2 KEYS WERE PRESSED IN THE SAME COLUMN?
Thanks for the kind words, Ron.
2 keys pressed in the same column would not cause an electrical problem. The idea is to avoid shorting two columns together because the columns are outputs; if one is sending out a 1 while the other sends out a 0, you'd be shorting Vcc to ground by pressing keys in both columns. The diode ensures that current can't flow out of a column when it outputs a 1.
@@RVCEET Wow, thanks Dr. Lombardo, good thing I asked. I'll set up a test using only one column at a time.
The only thing missing is the coding of the Microprocessor ??? Did I miss something here?
can anybody explain me why the input pins are not pulled up anymore in the last screen?
Or is there something I missed?
regards,
michael
Did you get an answer?
The link for the handouts is broken. :(
GReat video.
where is the sketch in arduino from your google drive?
I don't have any Arduino-specific material. The keypad scan is a generic algorithm - it works with any hardware.
Excellent video!!.This video cleared all my doubts.Thanks a lot.
Thank you awesome explanation. Great informative video
Thank you!
Nicely explained.
Excellent video! Cheers!
Thanks a lot, you saved my life! Brilliant video :D
perfect explaination
I had to really strain to hear this. we can always turn them down but when our volume is maxed out ..... Seems to be a great vid otherwise.
beautiful
thanks
Nice tech thank you sir
thnkyou ! :)
Thank you!