pic 16fxxx(HELP)

[deansmith]

Can anyone help me. I have made a circuit with a 16f84 and a matrix 4x3 keypad.The idea is to type a secret code in to trigger a relay as a door opener. I have also made a IR circuit with a 16f84. Igot the scemetics and ASM / HEX codes from various internet sites. Im still in the learning stages of electronics,and have been trying to find a way to combine the two circuits. The end result i want ,is to replace the matrix keypad with a IR sensor and tip the secret number from a remote control. I also want to put a 2 minute delay through an interruppt.I managed this with 2 555 timers, but want to keep it compact .I dont want to use extra ICs if it can all be done on a single PIC.
I have recently learnt that the 16f628 has more I/O ports (16)and a built in quarz. would this be a better choice ,??? Would 13 I/O be enough with the 16f84???

 

[kchriste]

16F628A is newer than the 16F84, but if you have the 16F84 then you may as well use that. You should have enough IO using either chip especially if you eliminate the keypad.

I dont want to use extra ICs if it can all be done on a single PIC.

You should be able to do it all with the PIC; no 555's needed.

 

[eblc1388]

I also want to put a 2 minute delay through an interruppt.

One usually cannot have a 2 minute interrupt that long. The reason being PIC executes instructions so fast that even counting 65536(16-bits) would take but a brief moment.

But it is easy to have a fast interrupt adding counts to other registers and such would allow the programmer to test the resulting count and use it to emulate very very long interrupt like days, weeks or months.

 

[eng1]

I have recently learnt that the 16f628 has more I/O ports (16)and a built in quarz. would this be a better choice ,??? Would 13 I/O be enough with the 16f84???

The PIC16F628A has more features and it is usually cheaper. But the number of I/O pins is not an issue for your application. A small PIC12F629 with 6 I/O pins, 1024 kB program memory, and internal oscillator can be used as well.
If you want to re-program the PIC for other applications, then get a PIC16F628A. If not, a the 12F629 seems an interisting option to me.

 

[eblc1388]

A small PIC12F629 with 6 I/O pins, 1024 kB program memory, and internal oscillator can be used as well.

That's a lot. As Bill Gates said "640KB should be enough for everyone".

 

[eng1]

LOL I was suggesting a SMALL PIC with HUGE memory?!? 1024 words!!!
Thank you eblc1388