hope you are doing fine ,
I have keyboard with ribbon cable , which it has 32 pins to atemga328p and read multi input in same time , i read about CD74HC4067 mux/demux , but the issue with this chip i only read one single input at time , i mean if the pin1 and pin13 rise up , i can read one of them not both .. what the best solution to connect the keyboard ribbon cable with my atemga using extrernal chip .
the link show some connect this ribbon cable with Tennsy wich have enough pins to detect the change on the pins ...
How to Make a USB Laptop Keyboard Controller: This Instructable will provide a step by step procedure for building a USB laptop keyboard and touchpad controller. I created this guide and video to hopefully make it easier for people to re-purpose an old laptop. A typical laptop relies on the mot…
www.instructables.com
thank you in advance and any suggestion will be appreciated
I imagine somewhere in the path is something which converts the keypress to an ASCII value? An IC? Circuit? Calculation? Then you have an ASCII value (7 or 8 bits).
After that it's carried on one data wire as a series of bits.
Suppose you multiply incoming pins each by a different power of 2, then sum them? Binary weighted resistors? Etc.
Do keypresses convey through a grid like below? Maybe 8x8 (making a total of 256 ASCII values)?
Scan rows & columns rapidly (50 times per second).
When you detect a keypress, calculate the ASCII value.
Then send it as a series of bits to your device's input pin.
If you want to detect multiple keys pressed at the same time (this is how I understand your post)
then neither Dana's circuit nor Brad's circuit work (without modifications).
Modifications on Dana's circuit: it needs individual resistors in series to each switch...
Modificatiins on Brad's circuit: it needs diodes in series with each switch.