Technology
PIC based kitchen countdown timer

Pickeypad
The most Mad-max kitchen timer I’ve seen today…

“It’s a kitchen timer. Use it to time spaghetti, or maybe an egg. It uses two PICs, one acts as a keyboard encoder, the other drives the display and supports the timer functions. You key in the desired time and press ‘#’. It’s accurate to 1/100th of a second, which can make all the difference I’m sure you’ll agree.” [via] – Link.

Related:

  • Make a cheap electronic timer – Link.
  • 555 timer projects – Link.
  • PIC projects @ MAKE – Link.

14 thoughts on “PIC based kitchen countdown timer

  1. Good idea, horrible design.

    Why would you use a 16F84? The part is very obsolete.

    A 16F628 is 1/3rd the price and does everything the F84 can do plus much more. Instead of bitbanging your serial communication on the F84, you can use the USART on the F628 to do it automatically for you. Once you’ve used a USART, you will cringe and the thought of having to go back to bitbanging.

    Also, while maintaining the 18-pin package the F628 has more I/O lines and it looks like you’d have had enough I/O to get by with one chip F84, making the serial issue moot.

    When you’re short I/O, moving to a second MCU is never a good solution. A better solution would have been a serial port extender or a shift-register. Even better than that, you’re dealing with a fairly small chip. Move up to a 28-pin 16F876 and you can replace both PICs and the 74154 decoder with a single chip.

    This one-chip design would also greatly simplify your hardware and firmware as well.

    The LEDs look nice, but did you consider a back-lit character LCD? LCD modules give a much more polished look and you can control a cheap parallel LCD directly off 6 I/O lines from the MCU.

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