I'm looking to turn on a relay threw a logic signal from a keypad. I need to know if there's a programmable keypad I can buy (off the shelf) that already has all the circuitry to program in a number (say 4 digits) and have a TTL type output that will go high when the correct number is typed.
This is my first post here and I've never been on this site so if I'm posting in the wrong spot I apologize.
I'm looking to turn on a relay threw a logic signal from a keypad. I need to know if there's a programmable keypad I can buy (off the shelf) that already has all the circuitry to program in a number (say 4 digits) and have a TTL type output that will go high when the correct number is typed.
This is my first post here and I've never been on this site so if I'm posting in the wrong spot I apologize.
I don't know of an existing programmable keypad, but a 4x4 would be easy to set up as you have suggested if you just hook it up to a uC. Have the uC watch for the correct code on the keypad, and respond accordingly.
I don't know of an existing programmable keypad, but a 4x4 would be easy to set up as you have suggested if you just hook it up to a uC. Have the uC watch for the correct code on the keypad, and respond accordingly.[/quote]
I don't have a good feel for how easy (or difficult) this really is. I've got almost no experience writing code.
If you have little experience it may be hard, but you are going to need to do some programming to get a project like this done.
Basically, you set up the 4x4 keypad to come in on an eight bit port, then map the byte to a keypress (be sure to debounce as well, either software or hardware). Store the last X bytes in RAM, and compare the sequence with the code in EEPROM. When they match, trigger another I/O line to send the signal that the code was inputed correctly, and have this trigger your relay, etc.