Digital alarm clock

[bex_445]

Hi,
I have been playing with pics over the last few weeks and have managed to do a few simple circuits like flashing leds, displaying txt on an lcd etc. I have worked through a few tutorials writting in both assembly and c. I prefer writing in c.

Now that I have learnt the basics I have decided to go further by making a digital alarm clock but I dont know where to go from here.

I assume that I will need to usd timers? but how? do I use 3 timers (hours, mins, secs) or just one running count and use math to get the hours, mins, secs?

Will I need an external oscilator or crystal? how precise is the built in one?

I am sure there is more questions but I cant think if any at the moment.

So far I have been using the 16f628 and a hitachi lcd. I know I will likely need a 16f877 for future projects but the 628 should still be ok for this project?

thanks

 

[kpatz]

Do a search, there's a bunch of folks on here who have made clocks using PIC chips.

Typically on a mid-range PIC you would run Timer1 with a 32.768 KHz crystal. This will generate an interrupt every 2 seconds by default, and with a little bit of code you can change it to 1 second or less. Use this to increment your seconds, minutes, hours, etc.

You'll need a crystal as the internal RC oscillator isn't accurate enough for a clock.

 

[bex_445]

I have tried searching the forum and google but have only found either clocks using 7 segment displays or written in assembly. I would like to use an lcd and c

 

[birdman0_o]

If you know what your doing, what your asking is extremely easy. Set up the LCD and print the hours , mins , secs registers onto it. A 7 seg would require a bit more thinking.

 

[Mr RB]

Try here, there is a clock project using text LCD and C source code;
Shift1-LCD Projects

**broken link removed**

If you are not already using MikroC you can download the free (2k ROM) demo version from MikroElektronika.