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'[PIC]: 12xxx advice'
2001\02\05@072208 by Roman Black

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Hi Guys, I need some advice re the 12xxx series PICs.
I'm quite competent with the PIC flash chips, and
over the last two years have made some larger projects
with 16F84A and 16F877 etc with no problems.

I am considering a new product with very basic
performance, like three logic chips would probably
do the task. Hence the 12C508!

I have done some homework and studied the 12xxx
datasheet. No problems there, even with 2 level
stack and 25 bytes ram. But I have never worked with
12xxx series PICs. Can someone give me an idea of
prices re 12C508 and 12C508A in DIP (100 quantity)??

Also, I am not looking forward to working with UV
erasable PICs. Is there an eraser I can build cheaply
and easily? I do own a 1000W UV solarium bed!! :o)

Any advice re using these parts would be appreciated.
Looks like I can code and test the main functions
on a 16F84, allowing for using only the smaller
instruction set of course. This will help speed up
development time a lot.

Thanks! :o)
-Roman

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2001\02\05@082038 by NDuckworth

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Make sure you read (using MPLAB) and write down the oscillator calibration
value for the windowed 12C508 because it's lost when you U/V erase it.

I have three windowed 12C509's and have individually numbered them because the
calibration values are different in each one.

Hope this helps.

Nigel


On Monday, February 05, 2001 12:19 PM, Roman Black [SMTP:.....fastvidKILLspamspam@spam@EZY.NET.AU]
wrote:
{Quote hidden}

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2001\02\05@084728 by Bob Ammerman

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Roman,

You've got the right idea of doing your development on the 16F84 (or even
better an 16F87x with ICD, but I digress).

On my first 12C project I did just this -- started with MPSIM, then a 16F84,
and by the time I burned the 12C it was _perfect_ the first time.

I'm afraid you're gonna just have to buy a few JW's and an eraser (a 1KW
tanning bed is probably the wrong intensitity and wavelength, and a small
'pocket' eraser will pay for itself in reduced power consumption and
convenience very quickly.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

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2001\02\05@095736 by Olin Lathrop

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> Any advice re using these parts [12C508A] would be appreciated.
> Looks like I can code and test the main functions
> on a 16F84, allowing for using only the smaller
> instruction set of course. This will help speed up
> development time a lot.

Why?  12Cxxx project tend to be simple enough that 90% or more of debugging
can be easily done with the simulator.  Once you start trying things out
with real chips, UV erasable parts are faster to program than flash parts.
By the time you're to the 90% debugged level, you will need to test with
real chips anyway.

It sounds like you have plenty of PIC experience and have done your
homework.  One gotcha that I can think of with these parts is that you can
only CALL to the first 256 program memory locations.  This means all lookup
tables and all subroutine entry points need to be in the first half of
program memory.


*****************************************************************
Olin Lathrop, embedded systems consultant in Devens Massachusetts
(978) 772-3129, olinspamspam_OUTembedinc.com, http://www.embedinc.com

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2001\02\05@130827 by mike

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On Mon, 5 Feb 2001 23:18:52 +1100, you wrote:

>Hi Guys, I need some advice re the 12xxx series PICs.
>I'm quite competent with the PIC flash chips, and
>over the last two years have made some larger projects
>with 16F84A and 16F877 etc with no problems.
>
>I am considering a new product with very basic
>performance, like three logic chips would probably
>do the task. Hence the 12C508!
>
>I have done some homework and studied the 12xxx
>datasheet. No problems there, even with 2 level
>stack and 25 bytes ram. But I have never worked with
>12xxx series PICs. Can someone give me an idea of
>prices re 12C508 and 12C508A in DIP (100 quantity)??
Around US$1 Use the -A version, it's cheaper.
>Any advice re using these parts would be appreciated.
>Looks like I can code and test the main functions
>on a 16F84, allowing for using only the smaller
>instruction set of course. This will help speed up
>development time a lot.
Set up an assemble-time option to switch between the 2 part types, and
conditional assembly to set things like processor type, SFR and
register locations. If you just debug on the F parts and then change all the code to 5x,
you WILL find an obscure problem later that would have been much
easier to debug on the flash parts!

REMEMBER TO READ THE INTRC CALIBRATION VALUES OUT OF NEW JW DEVICES
BEFORE ERASING, AND WRITE THEM ON THE BOTTOM OF THE CHIP! A few other gotchas : Note that the TMR0 int/ext selection in OPTION overrides TRIS bit 2,
forcing it to input in external clock mode.
Remember that GP3 is always input only if not used as reset
When GP3 used as reset, it ALWAYS has a pullup - this can be a real
pain for some simple brownout circuits.

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2001\02\05@135652 by Dwayne Reid

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At 09:42 AM 2/5/01 -0500, Olin Lathrop wrote:
> > Any advice re using these parts [12C508A] would be appreciated.
> > Looks like I can code and test the main functions
> > on a 16F84, allowing for using only the smaller
> > instruction set of course. This will help speed up
> > development time a lot.
>
>Why?  12Cxxx project tend to be simple enough that 90% or more of debugging
>can be easily done with the simulator.  Once you start trying things out
>with real chips, UV erasable parts are faster to program than flash parts.
>By the time you're to the 90% debugged level, you will need to test with
>real chips anyway.
>
>It sounds like you have plenty of PIC experience and have done your
>homework.  One gotcha that I can think of with these parts is that you can
>only CALL to the first 256 program memory locations.  This means all lookup
>tables and all subroutine entry points need to be in the first half of
>program memory.

Olin has pretty much hit the nail exactly on it's head - just jump in and
do it.

I now do most of my PIC stuff using the 12c508 and 12c671 parts - bit
banged SPI gets me my i/o since most of the i/o has to drive relay coils
anyways (we use LOTS of TPIC6B595 shift registers!).

Just one clarification in regards to CALLing subroutines in the 12C50x
parts - jump tables and subroutine entry points are limited to the first
256 bytes ON EACH PAGE.  The 12c508 has one page, the 12c509 has TWO pages
(1k code space total).  Thus, if you run out of jump table space or
subroutine entry space in a 12c508, you can migrate to a 12c509 for only a
few pennies more.

As far as cost is concerned, we purchase somewhere between 5k and 10k
annually and pay about $1.27 Canadian.  Given the lousy state of the
Canadian$, that would be about $0.80 US.  I understand that the price is
less than $0.50 US in high quantities.

dwayne



Dwayne Reid   <RemoveMEdwaynerTakeThisOuTspamplanet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
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Celebrating 17 years of Engineering Innovation (1984 - 2001)

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2001\02\05@172908 by David Duffy

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Roman wrote:
>Hi Guys, I need some advice re the 12xxx series PICs.
>I'm quite competent with the PIC flash chips, and
>over the last two years have made some larger projects
>with 16F84A and 16F877 etc with no problems.
>
>I am considering a new product with very basic
>performance, like three logic chips would probably
>do the task. Hence the 12C508!
>
>I have done some homework and studied the 12xxx
>datasheet. No problems there, even with 2 level
>stack and 25 bytes ram. But I have never worked with
>12xxx series PICs. Can someone give me an idea of
>prices re 12C508 and 12C508A in DIP (100 quantity)??

12C509-04/P were AU$1.31ea last time from Future. (1 tube)
Can't remember what I paid for the JW's - maybe AU$15 ?

>Also, I am not looking forward to working with UV
>erasable PICs. Is there an eraser I can build cheaply
>and easily? I do own a 1000W UV solarium bed!! :o)

Jaycar have an eraser - about AU$120 RRP IIRC.
The JW's erase quite fast and program faster than the FLASH parts.

>Any advice re using these parts would be appreciated.
>Looks like I can code and test the main functions
>on a 16F84, allowing for using only the smaller
>instruction set of course. This will help speed up
>development time a lot.

I've used that trick a few times myself.
The 2 vs 8 level stack can bite you doing this sometimes.
Regards...

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2001\02\05@201213 by Roman Black

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Olin Lathrop wrote:
>
> > Any advice re using these parts [12C508A] would be appreciated.
> > Looks like I can code and test the main functions
> > on a 16F84, allowing for using only the smaller
> > instruction set of course. This will help speed up
> > development time a lot.
>
> Why?  12Cxxx project tend to be simple enough that 90% or more of debugging
> can be easily done with the simulator.  Once you start trying things out
> with real chips, UV erasable parts are faster to program than flash parts.
> By the time you're to the 90% debugged level, you will need to test with
> real chips anyway.


Good point. I do use the simulator. Just that the
main operation of this app is to perform different
functions based on the input signal's period.
Periods are long and this is always awkward to
simulate. Better to do in hardware, but I didn't
fancy doing repeated erasing with 1 hour erase
times or whatever. :o)

I've been spoilt with 16F84 and my ICSP protoboard,
i'm used to code/program/test cycles of
a minute or less. Yeah, I know, buy an ICE.


> It sounds like you have plenty of PIC experience and have done your
> homework.  One gotcha that I can think of with these parts is that you can
> only CALL to the first 256 program memory locations.  This means all lookup
> tables and all subroutine entry points need to be in the first half of
> program memory.


Thanks for clearing that up. I was reading the PC
info last night and wondered if there was some type
of funky page switching for calls... :o)

-Roman

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2001\02\05@201633 by Roman Black

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Bob Ammerman wrote:
>
> Roman,
>
> You've got the right idea of doing your development on the 16F84 (or even
> better an 16F87x with ICD, but I digress).
>
> On my first 12C project I did just this -- started with MPSIM, then a 16F84,
> and by the time I burned the 12C it was _perfect_ the first time.
>
> I'm afraid you're gonna just have to buy a few JW's and an eraser (a 1KW
> tanning bed is probably the wrong intensitity and wavelength, and a small
> 'pocket' eraser will pay for itself in reduced power consumption and
> convenience very quickly.


Thanks Bob, any sources for a cheap eraser? I
can build one if the light source is not critical.
And how long do they take to erase normally?

Also, have you been purchasing 12C508 or 12C508A
in 100+ quantities lately? Any things to watch there?

Last question (I promise!) if using the internal
4MHz osc on the OTP parts, does it need calibrating
or what range freq are they in?
:o)
-Roman

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2001\02\05@202707 by Roman Black

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Dwayne Reid wrote:

> Olin has pretty much hit the nail exactly on it's head - just jump in and
> do it.
>
> I now do most of my PIC stuff using the 12c508 and 12c671 parts - bit
> banged SPI gets me my i/o since most of the i/o has to drive relay coils
> anyways (we use LOTS of TPIC6B595 shift registers!).
>
> Just one clarification in regards to CALLing subroutines in the 12C50x
> parts - jump tables and subroutine entry points are limited to the first
> 256 bytes ON EACH PAGE.  The 12c508 has one page, the 12c509 has TWO pages
> (1k code space total).  Thus, if you run out of jump table space or
> subroutine entry space in a 12c508, you can migrate to a 12c509 for only a
> few pennies more.
>
> As far as cost is concerned, we purchase somewhere between 5k and 10k
> annually and pay about $1.27 Canadian.  Given the lousy state of the
> Canadian$, that would be about $0.80 US.  I understand that the price is
> less than $0.50 US in high quantities.

Thanks Dwayne! :o)
-Roman

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2001\02\05@203104 by Tony Nixon

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Olin Lathrop wrote:

> Why?  12Cxxx project tend to be simple enough that 90% or more of debugging
> can be easily done with the simulator.  Once you start trying things out
> with real chips, UV erasable parts are faster to program than flash parts.
> By the time you're to the 90% debugged level, you will need to test with
> real chips anyway.

Not so with ROMzap.

Stop - reprogram - go can be as easy as 1 mouse click and take less than
a second to update.

MKIII coming soon with PC controlled MCLR reset to make it even faster,
plus on board I2C EEPROM.


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Tony

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2001\02\05@204202 by Spehro Pefhany

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At 12:11 PM 2/6/01 +1100, you wrote:
>
>Thanks Bob, any sources for a cheap eraser? I
>can build one if the light source is not critical.
>And how long do they take to erase normally?

Bob may have a different answer, but for light ;-)
development use it is hard to beat the Datarase II,
available from Digikey etc. for about USD50 (with timer).

>Also, have you been purchasing 12C508 or 12C508A
>in 100+ quantities lately? Any things to watch there?
>wit
>Last question (I promise!) if using the internal
>4MHz osc on the OTP parts, does it need calibrating
>or what range freq are they in?

Check the data sheet for info on this, you have the
choice of using the calibration factor or not. There
are a lot of curves and so on describing how close the
internal oscillator is to 4MHz over temperature, from
unit-to-unit and all that rot.

Best regards,


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2001\02\05@204834 by Bob Ammerman

picon face
> Thanks Bob, any sources for a cheap eraser? I
> can build one if the light source is not critical.
> And how long do they take to erase normally?

I got a decent one with a timer from Digikey for $60 (??) or so. It is made
by WALLING, CO., model D II

It zaps most PICs in  under 10 minutes.

> Also, have you been purchasing 12C508 or 12C508A
> in 100+ quantities lately? Any things to watch there?

I don't usually do the buying, my cusomer's do...

> Last question (I promise!) if using the internal
> 4MHz osc on the OTP parts, does it need calibrating
> or what range freq are they in?
> :o)
> -Roman

Each individual PIC has a 'calibration factor' burned into it. (You have to
save and restore this for JW's).

See the data sheet for specifics on accuracy and stability across
temp/voltage. I usually think of it as 'about 10% or so'.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

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2001\02\06@090430 by Olin Lathrop

face picon face
> Good point. I do use the simulator. Just that the
> main operation of this app is to perform different
> functions based on the input signal's period.
> Periods are long and this is always awkward to
> simulate. Better to do in hardware, but I didn't
> fancy doing repeated erasing with 1 hour erase
> times or whatever. :o)

Most UV EPROM erasers erase in 20 minutes or less.  Mine can erase 4 chips
in 20 minutes.  As long as you have enough UV chips to keep the eraser busy,
you have an average throughput of one clean chip every 5 minutes.  I usually
get at least 8 chips when using UV erasables, and have never overrun the
eraser.  In other words, on average it takes longer than 5 minutes to burn a
chip, test it, figure out what you need to change, make the changes, and
rebuild.

> I've been spoilt with 16F84 and my ICSP protoboard,
> i'm used to code/program/test cycles of
> a minute or less. Yeah, I know, buy an ICE.

Yes, I think the ICE-2000 is a great tool that is well worth the investment
if you are in a situation where time is money.  However, I've never gotten
the modules for the 12C508A although I've probably done 5 to 10 projects
with those chips.  Given the limited memory, the program has to be simple.
I debug with the simulator and everything usually works the first time when
I burn chips.  Multiple iterations after that are usually to change
parameters like time constants, not to debug the logic.

I bet you can use the simulator to test your logic regardless of the long
periods.  Step thru the initialization and then watch it go into a wait loop
or whatever.  You can then diddle the internal state so that it thinks it's
been waiting a long time, then set a pin high or low.  You may also be able
to debug it with much shorter periods unless this changes the logic for some
reason.  It's usually not too hard to make it run thru each of the linear
code sections.

By the way, your test cycles with UV chips will be faster than with flash
chips because the UV chips program faster.  All in all I prefer doing
iterations with UV chips over flash chips.


*****************************************************************
Olin Lathrop, embedded systems consultant in Devens Massachusetts
(978) 772-3129, olinSTOPspamspamspam_OUTembedinc.com, http://www.embedinc.com

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2001\02\06@090631 by Olin Lathrop
face picon face
> Thanks Bob, any sources for a cheap eraser? I
> can build one if the light source is not critical.
> And how long do they take to erase normally?

I have a Datarase II, which can erase 4 chips in 20 minutes.  I sorta
remember that I got it from Jameco for well under $100.

> Last question (I promise!) if using the internal
> 4MHz osc on the OTP parts, does it need calibrating
> or what range freq are they in?

The W register gets loaded with the factory-determined calibration values
right before your code starts executing.  You can then write W to OSCAL if
you wish.  I sorta remember they actually write a MOVLW into the last
program memory location, then start execution there.  Whatever, this is all
spelled out nicely in the data sheet.


*****************************************************************
Olin Lathrop, embedded systems consultant in Devens Massachusetts
(978) 772-3129, spamBeGoneolinSTOPspamspamEraseMEembedinc.com, http://www.embedinc.com

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2001\02\06@091250 by mike

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On Tue, 6 Feb 2001 12:11:29 +1100, you wrote:

>Bob Ammerman wrote:
>>
>> Roman,
>>
>> You've got the right idea of doing your development on the 16F84 (or even
>> better an 16F87x with ICD, but I digress).
>>
>> On my first 12C project I did just this -- started with MPSIM, then a 16F84,
>> and by the time I burned the 12C it was _perfect_ the first time.
>>
>> I'm afraid you're gonna just have to buy a few JW's and an eraser (a 1KW
>> tanning bed is probably the wrong intensitity and wavelength, and a small
>> 'pocket' eraser will pay for itself in reduced power consumption and
>> convenience very quickly.
>
>
>Thanks Bob, any sources for a cheap eraser? I
>can build one if the light source is not critical.
>And how long do they take to erase normally?
You need a germicidal lamp, not a 'black light' or insect zapper tube.
The most common ones look like normal slimline (4/6/8 watt 6,9,12" I
think ) fluorescent tubes, but they are transparent (no phosphor), and
can be driven with the same type of ballast. You MUST use a
light-proof enclosure with an interlock as the UV can cause eye and
skin damage. Erase times are typically 5-10 mins.
Another type of bulb (don't know if it's still made) is the Philips
TUV, which needs no ballast.  The easiest (but probably not cheapest) source is often as 'spares'
for commercial UV erasers.

>Last question (I promise!) if using the internal
>4MHz osc on the OTP parts, does it need calibrating
>or what range freq are they in?
There is a calibration value programmed into OTP parts, which you need
to load into the OSCCAL reg by putting MOVWF OSCCAL at address 0. This brings the osc to within about 5% of 4MHz (check datasheet for
tolerance)

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