Clock-PIC
---------

Heres a release of an early development version of Clock-PIC, a video
clock.

The concept is Eric Smith's, but all the code and algorithms are
original to me. (Because Eric's version works on the PIC16C5x 16MHz
series - and I only had a 4MHz 16C84 hanging around).

This clock runs on a 4MHz PIC16C84. It outputs 625 line CCIR PAL (with
some insignificant alterations - the timings are rounded to the
nearest microsecond, and half length picture lines are replaced with
equalising pulses).

There are some parts yet to be coded - but as I'm leaving the Internet
very shortly, I thought it might be interesting to release it anyway.
(No clock setting code is present, and the date never advances - only
the time).

But the video generation does work - and thats the main thing :-)


Video D/A circuit to go with it:

         |   ___ 390R
      RA0|---___--------
         |   ___ 1K     |
      RA1|---___--------+
         |              +---------- CVBS out
                        |
                       | | 82R
                       | |
                        |
                       ---

This circuit produces (roughly) the following voltages.

RA1 RA0 out
-------------------------
+5V +5V 1.0V  white level
+5V  0V 0.3V  black level
 0V  0V 0.0V  sync level

The PIC runs off a 5V supply.

The clock uses an XT option 4MHz crystal. Use a crystal, not a ceramic
resonator, as the clock accuracy depends on it.

Anyway - I think that covers pretty much everything. Don't make any
money out of this without giving me a fair share. This file may only
be distributed on the Internet. No charge may be made for distributing
it.

Snail Mail:       Peter Knight
                  35 Mill Lane
                  East Halton
                  Grimsby
                  Humberside
                  United Kingdom
                  DN40 3QA

UK Phone:         01469 540827
World phone:      +44 1469 540827

Email:            I wish! :-(  If I get a new account, see you on the PIC list!
