Chip with simple program for Toy

[Danny T]

Anthony Fremont wrote:

I always wanted to put a pic, a lithium battery, a hall sensor (or MEMS
accelerometer to be really cool) and a column of LEDs into a pendulum
bob. Then the swinging column of LEDs could strobe out the date/time in
a format suitable for people that have problems with analog dials and
hands. ;-) I really have to get this done.

Sounds like fun! Just make sure you're not posessed to get Blue LEDs...
Can we say tacky?

Yes, you would pick your resistor size so that enough current could be
supplied to the device being switched on and off.

I believe one resistor would do all the pins.. I'm not sure how that
would work though, given I'd end up with different currents depending on
how many pins where high/low!

You can do it either way you prefer. Many CMOS parts are better at
sinking current than sourcing it, but the PICs have the same limit
either way (usually 25mA per pin)

When the PIC is outputing a 0, then it is actively driving the pin low
and can sink current. When it is outputing a 1, it is actively driving
the pin high (except RA4) and can source current. If you hook two PICs
together and try to have a dualing outputs contest, one of the pins will
not survive. Always use a current limiting resistor between pins that
might try to do this.

Do you mean having the output of a pic fed to the input of another? Like
I need for my clock? Should I put resistors between them?

Oh, and each output from my "driver" is connected to 4 inputs (one from
each of the other pics) - anything I should be careful of there - 4
inputs probably draw 4 times as much current - is there a problem here?


--
Danny

 

[Anthony Fremont]

"Danny T" <danny@nospam.oops> wrote in message
news:41ea897d$0$16530$ed2619ec@ptn-nntp-reader02.plus.net...

Anthony Fremont wrote:

The ones that are best will be the ones that make your crystal
oscillate
at exactly the right frequency, and start-up every time you apply
power.
;-) You will probably want to use two 22pF ceramic caps.

Grrr...!

*looks in bag*

Why the hell can't they label caps properly?! My 100n caps are
labelled
"10", and the 1u are labelled "105"... Is there a nice big table
somewhere that'll tell me all the possible things 22pF caps could be
labelled as? (and why did you say 22?)

They usually have the cryptic value of "22" printed on them, plus the
size is kind of a giveaway. ;-) I said 22, because that's what I've
always used and it works. But a better reason would be that the
datasheet calls for 15 to 33pF of capactance for each cap. The real
determining factor is whatever the crystal manufacturer calls for to
bring the crystal to the right frequency. 22pF works pretty well in
practice. It's only really critical when you are trying to keep
precision time over a long period.

Very small caps are best at passing thru only the highest
freqencies.
Glitches on the power line are usually at quite high frequencies.
And
yes some of your oscillator is being leaked to ground. It's ok,
otherwise the crystal might fracture under the stress of too much
feedback.

Right


Well, the interrupt routine must not save and restore the W, STATUS
and
possibly FSR and PCLATH when it executes. Otherwise things go to
pieces
in a big hurry. Preventing "collisions" between the ISR and main
level
is not that hard.

Check my code in a.m.8bit - doesn't seem to work :-(

Check my reply, you need to make changes. ;-)

I read about that... I'm sure I won't make that mistake...
(well, I won't post it here when I do, at least ;-))

Yeah you will, you just won't know that's what's happening. You
will be
certain that the processor is not executing instructions properly.
;-)

I'm certain it's not, but I am using RETFIE and clearing my interrupt
flag first

Your code looks ok in this respect.

 

[Anthony Fremont]

"Danny T" <danny@nospam.oops> wrote in message
news:41ea8e45$0$44892$ed2e19e4@ptn-nntp-reader04.plus.net...

Anthony Fremont wrote:

I always wanted to put a pic, a lithium battery, a hall sensor (or
MEMS
accelerometer to be really cool) and a column of LEDs into a
pendulum
bob. Then the swinging column of LEDs could strobe out the
date/time in
a format suitable for people that have problems with analog dials
and
hands. ;-) I really have to get this done.

Sounds like fun! Just make sure you're not posessed to get Blue
LEDs...
Can we say tacky?


Yes, you would pick your resistor size so that enough current could
be
supplied to the device being switched on and off.

I believe one resistor would do all the pins.. I'm not sure how that
would work though, given I'd end up with different currents depending
on
how many pins where high/low!

You only have to worry about pin RA4, the others are fine.

You can do it either way you prefer. Many CMOS parts are better at
sinking current than sourcing it, but the PICs have the same limit
either way (usually 25mA per pin)

When the PIC is outputing a 0, then it is actively driving the pin
low
and can sink current. When it is outputing a 1, it is actively
driving
the pin high (except RA4) and can source current. If you hook two
PICs
together and try to have a dualing outputs contest, one of the pins
will
not survive. Always use a current limiting resistor between pins
that
might try to do this.

Do you mean having the output of a pic fed to the input of another?
Like
I need for my clock? Should I put resistors between them?

It wouldn't hurt for you to do that (1k should work fine), but it's
important when you have pins that flip from being input to output on the
fly when trying to communicate bidirectionally. Eventually something
leads to things being out of sync and then you have battling outputs.
When one pin is *outputting* a 1 and the the other is *outputting* a 0,
it's a short circuit.

Oh, and each output from my "driver" is connected to 4 inputs (one
from
each of the other pics) - anything I should be careful of there - 4
inputs probably draw 4 times as much current - is there a problem
here?

CMOS inputs draw very miniscule amounts of current, almost 0.

 

[Miles Harris]

On Sat, 15 Jan 2005 23:43:27 -0500, John Popelish <jpopelish@rica.net>
wrote:

If E=IR can we just then increase the resistance and get as many volts
as we want?

If you have a current source (that provides as many volts as it takes
to push a fixed current through a resistance), then, yes.

I appreciate where you're coming from on this one, John. Also, JK's
explanation was outstanding in detail and clarity.
However, it's confusing to introduce a newbie to the concept of the
current source. It doesn't exist in the real world as we know. No one
- to my knowledge - has mentioned the essential missing ingredient
here: the battery's _internal resistance_. This is what the OP really
needs to be informed about, but I'm not apparently very good at
expounding the basics, or so I'm told. Can someone please elucidate in
a language the OP will understand?

 

[John Popelish]

Miles Harris wrote:

On Sat, 15 Jan 2005 23:43:27 -0500, John Popelish <jpopelish@rica.net
wrote:

If E=IR can we just then increase the resistance and get as many volts
as we want?

If you have a current source (that provides as many volts as it takes
to push a fixed current through a resistance), then, yes.

I appreciate where you're coming from on this one, John. Also, JK's
explanation was outstanding in detail and clarity.
However, it's confusing to introduce a newbie to the concept of the
current source. It doesn't exist in the real world as we know. No one
- to my knowledge - has mentioned the essential missing ingredient
here: the battery's _internal resistance_. This is what the OP really
needs to be informed about, but I'm not apparently very good at
expounding the basics, or so I'm told. Can someone please elucidate in
a language the OP will understand?

I don't like to try to explain everything in a single post, but try to
guess what the op is ready to soak up in one dose. If he asks further
questions, I will try to guess what he is ready for, then. I didn't
think that the question of source resistance was needed at this place
in his education, but I will be watching for the opportunity to inject
it. If your judgment differs, by all means jump in with both feet.

--
John Popelish

 

[Andrew Holme]

John Popelish wrote:

About half of all the electrical energy that is generated is lost
heating the resistance of the distribution grid.

Are you sure about that, John? I find that hard to believe. Googling for a
figure, I found this:

http://healthandenergy.com/electric_power_grid.htm

It says:

"Seven percent of the energy is lost in transmission," said George David,
chairman and chief executive of United Technologies, which is based in
Hartford. "The solution is to put power generation much closer to where the
electricity is consumed."

 

[Andrew Holme]

John Popelish wrote:

About half of all the electrical energy that is generated is lost
heating the resistance of the distribution grid.

http://www.schoolscience.co.uk/content/5/physics/copper/copelech5pg2.html

says:

"In the UK, about 8.5% of all generated electricity is wasted in the grid
and distribution system."

 

[Bob]

Wow guys, thank you very much for explaining everything so quickly and
in such a maner that it finally makes sense.

Grab the water faucet with the other hand, and that potential will
drive current through you on its way to ground, and you will be
shocked by the current passing through you.

Yes!! This is a great way to learn. You can only learn so much from books.
Experimentation is the key to a long, successful, career in electronics.

As a great philosopher once said:

"Give a man a fire and he'll be warm for a day. Set a man afire and he'll be
warm for the rest of his life."

Bob

 

[Miles Harris]

On Sun, 16 Jan 2005 21:45:46 GMT, "Bob"
<nimby1_notspamm_@earthlink.net> wrote:

Grab the water faucet with the other hand, and that potential will
drive current through you on its way to ground, and you will be
shocked by the current passing through you.

Yes!! This is a great way to learn. You can only learn so much from books.
Experimentation is the key to a long, successful, career in electronics.

ROTFLMAO!!
Thanks, Bob. I can always use a bit of humor to lighten an otherwise
dull day.

 

[Lee Waun]

N

Wow, -6 degrees. I feel sorry for you folks; must be
terrible! Shall we send emergency aid?

No no need to panic. The cold spell has ended and it is raining and 6

degrees out. Luckily the rain is now melting that snow we had. We have
bylaws outlawing snow here. Snow is for the rest of the country. We don't
allow it here.

Come and visit Winnipeg. -29 now (mid afternoon; with -34 forecast
for tonight. And that doesn't include the windchill... with
it it will drop to the mid -40's :

Only fools and my brother and sister live in Winterpeg. There is a reason it

is called winterpeg.

 

[John Fields]

On Sun, 16 Jan 2005 16:47:49 GMT, Miles Harris <mazzer@yahoo.com>
wrote:

On Sat, 15 Jan 2005 23:43:27 -0500, John Popelish <jpopelish@rica.net
wrote:

If E=IR can we just then increase the resistance and get as many volts
as we want?

If you have a current source (that provides as many volts as it takes
to push a fixed current through a resistance), then, yes.

I appreciate where you're coming from on this one, John. Also, JK's
explanation was outstanding in detail and clarity.
However, it's confusing to introduce a newbie to the concept of the
current source. It doesn't exist in the real world as we know.

---
Yes, it does. an _extremely_ common example is a high voltage being
fed, through a high value of resistance, to a load which requires a
constant current. An arguably less common example is a current
regulating diode.
---

No one - to my knowledge - has mentioned the essential missing ingredient
here: the battery's _internal resistance_. This is what the OP really
needs to be informed about, but I'm not apparently very good at
expounding the basics, or so I'm told. Can someone please elucidate in
a language the OP will understand?

---
Why don't _you_ give it a try and see how you do? If you make any
mistakes I'm sure _someone_ will correct you.

--
John Fields

 

[Miles Harris]

On Mon, 17 Jan 2005 20:26:05 -0600, John Fields
<jfields@austininstruments.com> wrote:

Yes, it does. an _extremely_ common example is a high voltage being
fed, through a high value of resistance, to a load which requires a
constant current. An arguably less common example is a current
regulating diode.

I'm talking about a _perfect_ current source, Junior. Surely even
*you* must have worked that out.

No one - to my knowledge - has mentioned the essential missing ingredient
here: the battery's _internal resistance_. This is what the OP really
needs to be informed about, but I'm not apparently very good at
expounding the basics, or so I'm told. Can someone please elucidate in
a language the OP will understand?

---
Why don't _you_ give it a try and see how you do? If you make any
mistakes I'm sure _someone_ will correct you.

That "someone" will 'correct' me even if I don't make any mistake, it
seems. :-/

 

[Richard Harris]

Hi,
I found some nice documents on electronics that comes with an index. These
may help ya with basic stuff.

http://www.radioelectronicschool.com/reading/

 

I found EMAC <http://www.emacinc.com/> has several 8085 based
trainers. Any recommendation on these?

Elenco <http://www.elenco.com/> has one 8085 based trainer, it
appears
to be a good value for the money. Opinions?

Cygnal
http://www.silabs.com/products/microcontroller/developmenttools.asp
has 8051 based trainers with varying configurations.

Flite <http://www.flite.co.uk/micros.html> has quite a few trainers,
including Motorola based 68x trainers. If my nephew does well with
the
intel based trainers, I think he would be interested in these, but
any
other recommendations?

I am curious which one you went with. I am considering EMAC's as it
seems to be the most advanced for the cost as it is only slightly more
expensive then Elenco's if you assemble it yourself.

Thanks,

Tom

 

[Miles Harris]

On Tue, 18 Jan 2005 17:17:42 -0600, John Fields
<jfields@austininstruments.com> wrote:

Wrong again, Junior. It was John Popelish that introduced the current
source in his first response on this thread. It was clear that he was
also talking about a perfect current source:

JP:
If you have a current source (that provides as many volts as it takes
to push a fixed current through a resistance), then, yes.

---
As far as I can tell, JP was expounding on the _concept_ of a current
source, which does assume ideal conditions

So you retract your earlier mis-statement? That's a welcome change.

Moreover, John clearly defined his terms in order to, ostensibly,
remove any ambiguity from his argument, so his meaning was perfectly
clear.

It certainly was. And yet again you failed to pick up on it, Junior.
Are you actually bunking off high school.... or _grade_ school? Don't
they teach English any more in American schools? I saw something on
the news tonight that indicated Darwin and his work was to be dropped
from the curriculum so I guess anything's possible these days in the
good ol' US of A.. :-(
I won't bother to request an apology for obvious reasons...

 

[Don Kelly]

I'm sure that John Fields and John Popelish are both well versed in this
simplified introductory material - and a hell of a lot more. .

--
Don Kelly
dhky@peeshaw.ca
remove the urine to answer

"Richard Harris" <richard_harris_2@hotmail.com> wrote in message
news:csjbo8$5ie$1@hercules.btinternet.com...

Hi,
I found some nice documents on electronics that comes with an index.
These
may help ya with basic stuff.

http://www.radioelectronicschool.com/reading/

 

[Michael Black]

Rich Webb (bbew.ar@mapson.nozirev.ten) writes:

On 18 Jan 2005 08:52:52 -0800, tom@wattservices.com wrote:


I found EMAC <http://www.emacinc.com/> has several 8085 based
trainers. Any recommendation on these?

Elenco <http://www.elenco.com/> has one 8085 based trainer, it
appears
to be a good value for the money. Opinions?

Cygnal
http://www.silabs.com/products/microcontroller/developmenttools.asp
has 8051 based trainers with varying configurations.

Flite <http://www.flite.co.uk/micros.html> has quite a few trainers,
including Motorola based 68x trainers. If my nephew does well with
the
intel based trainers, I think he would be interested in these, but
any
other recommendations?

I am curious which one you went with. I am considering EMAC's as it
seems to be the most advanced for the cost as it is only slightly more
expensive then Elenco's if you assemble it yourself.


Ahh, must be from Google. A reply to a thread six months dead and with
a broken References line. Yup, Google indeed.

From http://www.google.com/governance/conduct.html

Our informal corporate motto is "Don't be evil."

Which is slightly out of date. I'm guessing that the current motto is
"Maximize shareholder return."

It certainly isn't "Respect the wishes of the usenet community."

I've just realized what I'm going to do with messages posted via

google that are replies to old messages.

One thing they've added to the new interface is a "report abuse"
link. In keeping with there lack of distinction between "google
groups" and Usenet, most of the check boxes are about their
"google groups" but there is an "other" box. So I figure I'll
fill out one of those forms each time I see a reply to a message
older than a month (which was google's previous limits on replies),
especially when the poster doesn't bother to even quote the message
they are replying to.

If they get enough of such abuse messages (and I realize it's not quite
abuse to reply to an old message, but I'd say google is abusing Usenet
by the lack of a time limit for replies, and their blending of their
groups with Usenet), perhaps they will realize it is an error.

They've already messed up the historic archives (which they boasted
about when they added them back in 2001, and highlight some key posts
on a timeline) with this, since the equivalent of graffiti artists
have posted replies to some of the messages that google themselves
have listed as historic.

Michael

 

[John Fields]

On Wed, 19 Jan 2005 04:41:37 GMT, "Don Kelly" <dhky@peeshaw.ca> wrote:

I'm sure that John Fields and John Popelish are both well versed in this
simplified introductory material - and a hell of a lot more. .

---
That's very kind. Thank you.

--
John Fields

 

[Rich Webb]

On 18 Jan 2005 20:45:47 -0800, "Cmd Buzz Corey" <nbcblue@hotmail.com>
wrote:

[A deleted reply to a thread that was born & died in the summer of 2001]

I need to get a new news reader. This one can't kill filter on
"Message-ID: contains 'googlegroups.com'".

--
Rich Webb Norfolk, VA

 

[John Fields]

On Wed, 19 Jan 2005 13:51:49 -0600, "Trudeau" <Trudeau@123.com> wrote:

On the following link it says in part the following....

Most diacs are used for pulse generation, probably in the order of amps, and
are designed as such. I think the published ratings for static (DC) use are
a bit on the consevative side, take a 1N4148 sized diac and say 100 to 200
mW dissipation and about 2V across the diac we are left with 50 to 100 mA,
more than enough!

http://www.hut.fi/Misc/Electronics/circuits/tele_privacy.html

My question is, Is this web site confused.

---
No. Notice they were referring to a 1N4148 _sized_ diode. That is, a
Diac in the same size package as a 1N4148.
---

When I looking up a 1N4148 it is
NOT a Diac, it is a Diode. Please bear with me as I'm a novice.
A Diac goes in one direction and will start conducting electricity
at a certain voltage. I Get that.

---
No, you don't. Not quite, anyway. A Diac is bidirectional.

http://www.littelfuse.com/cgi-bin/r.cgi/prod_series.html?LFSESSION=Stkas7zMnz&SeriesID=605
---

A diode works in one direction also but from that point I'm a little unsure
what the difference is. Can anyone explain this in simple terms?

---
A diac is a full-wave or bidirectional thyristor. Whenever the
amplitude of applied voltage exceeds the breakover voltage rating of
the diac, it switches from blocking- to conducting-state.
---

Does the Diode also limt voltage eg. a 5v Diode limits voltage to well .. 5V.

---
A reverse-biased Zener diode forced into conduction will cause the
voltage across its junction to be limited to the value specified in
the data sheet for that diode with the specified current flowing
through the diode. Forced to conduct in the forward direction, the
voltage across the diode, and most silicon junction diodes, will be
substantially less than one volt,

--
John Fields