Title: [Entry] Hex KeyPad
Post by: adamsc on October 17, 2011, 06:11:58 am
Post by: adamsc on October 17, 2011, 06:11:58 am
This is a handy device for prototyping, etc... It's a hexadecimal keypad (0..9, A..F) that outputs the hexadecimal value on 4 digital binary lines (one nibble). It has both active high and active low output (so it'll work for any system), as well as active high and active low strobe outputs for when the data is on the lines. I also added an on/off switch for convenience.
Here's the schematic:
[attachment=1]
The video link below shows the device hooked up to some bargraph LEDs to show the output value and a couple of regular LEDs to show the strobe outputs. I built the key pad from an old keyboard I had. I basically cut out a section of the keyboard that was 4x4 keys, swapped out some keys to create the 0..9 and A..F, then hooked it up to the rest of the circuit. Sadly, the 0 key was lost, so it's not on there. But, the fun part is that you can see into the key itself to see how it works! :-)
Using the Hex KeyPad Video: http://www.youtube.com/watch?v=dY6MK2XOlmc (http://www.youtube.com/watch?v=dY6MK2XOlmc)
Here's the schematic:
[attachment=1]
The video link below shows the device hooked up to some bargraph LEDs to show the output value and a couple of regular LEDs to show the strobe outputs. I built the key pad from an old keyboard I had. I basically cut out a section of the keyboard that was 4x4 keys, swapped out some keys to create the 0..9 and A..F, then hooked it up to the rest of the circuit. Sadly, the 0 key was lost, so it's not on there. But, the fun part is that you can see into the key itself to see how it works! :-)
Using the Hex KeyPad Video: http://www.youtube.com/watch?v=dY6MK2XOlmc (http://www.youtube.com/watch?v=dY6MK2XOlmc)