john1 said:You seem to think that this is possibly not the best way to go
about this. Maybe it isn't. There may well be a much better way
to log unattended events. If there is something i have missed
or haven't thought of that might be a better way to do this i
would be very interested.
john1 said:I have had a look for the tutorials you speak of, but i
seem to have missed them somewhere, and i cant find this
CMOS clock, maybe i'm looking in the wrong place ??
john1 said:Hi Nigel,
I found the 'Pic-prog' forums,
and ive been reading up a bit.
I will check that my low voltage
supply which is strung around various places in my home,
is at least 12 volts,
and i will look into making it around 12 and a half volts.
john1 said:The construction of that clock as shown is certainly within my resources, so long as the parts don't cost too much.
Although i don't really see how to read it, i know they cram
a lot into chips, but is this made to give the date/time
info as a serial stream from one of the legs ?
There doesn't seem to be enough legs for a straight parallel
output.
I am assuming that a Programmable Controller would be
needed to do what i want ?
I am also leaning toward using a print-roll output from
this unit, as it would be almost impossible to cheat it,
but to do that i would like it to type words as well as
numbers, single words would do, like,
GATE 16:00 13/01/04
DOOR 16:01 13/01/04
GATE 16:01 13/01/04
Having a socket to run the log into a laptop would be nice
and from what you said before, i think that is how you
envisaged using it anyway.
However first things first, your web page doesn't self-size
so reading it means panning left and right each sentence,
but i don't mind. (i copied to notepad after a while)
This taken from:
**broken link removed**
Appears to show that the chip would be ok up to six volts,
I have a small 3-pack of rechargeable cells, Ni-MH, i don't
know what Ni-MH is but the three give 3.9 volts, if i take
across only two i get 2.6 volts, so i am guessing that the
chip would be ok at 3.9 volts. I am assuming that the bat
in that diagram is kept up by leakage through the diode
that only comes into conduction if the supply fails, namely
the D2 diode 1N4148.
These batteries are out of an old mobile phone and may well
require a little more effort to keep them alive than the
reverse leakage from a 1N4148 so i would ask if there is
any reason why i shouldn't bridge that diode with a resistor
such as to give maybe a milliamp or so ?
( i don't have a battery like the one shown )
I have downloaded a PDF about that clock chip, it certainly
looks good enough for what i want.
One thing that i noticed is that it carries a section of
free ram for user use.
I can't quite make out how much. Surely it's not just 8
bytes ?
In fact i'm still struggling to see how to read the time
with it. Maybe it will all come clear soon ! And i'm still
trying to find the price !
Maybe the free ram could be used to make the words i want?
maybe not ... 8 bytes isn't much.
Cheers, John
john1 said:i found out a bit about 12C,
apparently its a sort of double serial two wire feed.
First ive ever heard of it.
still, live and learn.
I'm guessing that there will be a chip to convert to
seven segment displays, and as needed for the months
and days, if wanted. i only actually want numbers,
but its nice to think that days or months could be
words if i wanted.
If the battery is likely to be a problem, i will mount
it off the circuitwork and make it easily remove-able.
The other thing is the crystal. I will have to go
through my collection and check just in case i have
one.
I could use a printer i suppose, but its not what i
have in mind, but it would be ok to get things going.
I have in mind one of those little till roll types.
Yes you're right, its not ram, its rom. Erasable rom
actually, i just called it that because thats what they
called it, i have no idea why they called it that.
I will try to find your LCD pages, but i never found
that clock until you gave me the page ....
You mention changing or setting the words brought up by
the incoming signals using a local keyboard, could this
be the same laptop used to download the log on 232 ?
Not that i am certain what 232 is, but i think its the
standard 8 bit interface usually using ascii coded
characters, it might also mean the whole hex range
ascii or not. I think its what they used to call
assembler, but i could easily be wrong.
First i spose i better get a PIC running, cos i can't
read that 12C clock without it. Unless you would
suggest a starting point?
The incoming signals are all 12 volt positive logic.
There are only six at the moment but another six are
in the pipeline.
Maybe that should be a starting point, maybe the six
incoming signals that i have should be converted to
a binary number and a KP (key-pressed) signal.
I will make a start on this by trying to fix up a
multiplexer chip to take on the incoming lines and
give a binary code for each. I am assuming that the
PIC chip will want the inputs in this manner, i hope
i am correct in that.
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