Searching \ for '[PIC]:F series' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/microchip/devices.htm?key=pic
Search entire site for: 'F series'.

Exact match. Not showing close matches.
PICList Thread
'[PIC]:F series'
2000\10\09@020010 by Tony Nixon

flavicon
picon face
Hi all,

HELP!!! I'm dying.....

Is there any difference in the 16F876 against the 16F873 apart from
ROM/RAM size?

Ever since I've changed from the F873 to F876 I can't get the programmer
project to work.

It appears to be a port problem although I can't put my finger on it.

I can program temp code (only about 100 words) into the 873-04P and run
it - the display shows "hello" in 4 bit mode ok.

I program the same code into a 876-20P - nothing.

Only Page 0 RAM is being used and all I'm using is RB0 to RB3, RA0 and
RA2.

A2D is set for all digital.

I bought a tube of 15 876's and none of them will run the code that the
873's do.

The code appears to work in the PIC as I have made a LED come on at
certain points right upto the end of execution.

Another thing I noticed, is that I program the PIC programmer code into
my usual programmer and the 876's won't work for at least 30 seconds
again after powering down. I can cycle the power immediately with the
873's with exactly the same code and fuse settings and it works
instantly everytime.

Just now to prove the point, I chopped off the new programmer code after
0FFFh, modified a few labels and 'dumped' it into a 873 chip and bingo
the project worked.


Boy, if this stuff doesn't send you to the grave or drive you to drink,
nothing will.

Just wondering if I got a dud batch of PICs.


--
Best regards

Tony

ICmicro's
http://www.picnpoke.com
spam_OUTsalesTakeThisOuTspampicnpoke.com

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's


2000\10\09@065322 by staff

flavicon
face
Tony Nixon wrote:
{Quote hidden}

I think this might be pointing to the problem, or at least one
problem. Especially the "taking 30 seconds after porgramming" bit...
Which programmer are you using? How are you setting the programmer to
handle each chip? Can you read the rom after programming and confirm
both 873 and 876 have the right code?

There is a functional difference between the 873 and 876 chips
that you may have missed, on the 876 the top 16 bytes of ram
are mirrored in every ram bank, in the 873 the two ram banks
are completely separate. I know you said you were only using ram
bank 0, but thought it was worth a mention.
-Roman

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's


2000\10\09@071017 by Alan B. Pearce

face picon face
What happens if you run your code in the MPLAB emulator, set up for the two different chip types? Just a thought, not knowing the specific differences between them, but is there a hard coded address somewhere??? For a clue check your statement :-

>I chopped off the new programmer code after
>0FFFh, modified a few labels and 'dumped' it into a 873 chip and bingo
>the project worked.

i.e. you changed something significant moving the code between chips!!!!!!!!

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's


2000\10\09@094046 by James Paul

flavicon
face
Hey Tony,

Try running the 876-20's at some frequency less than 20 Mhz.
Maybe they were mismarked, and won't run at 20 Mhz.  Just a
thought.  Let me know if this ios it.

I say this because I got an F84 one time that was marked 10,
but wouldn't run above 5.


                                            Regards,

                                               Jim

On Sun, 08 October 2000, Tony Nixon wrote:

{Quote hidden}

jimspamKILLspamjpes.com

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's


2000\10\09@094050 by James Paul
flavicon
face
Hey Tony,

Try running the 876-20's at some frequency less than 20 Mhz.
Maybe they were mismarked, and won't run at 20 Mhz.  Just a
thought.  Let me know if this is it.

I say this because I got an F84 one time that was marked 10,
but wouldn't run above 5.


                                            Regards,

                                               Jim

On Sun, 08 October 2000, Tony Nixon wrote:

{Quote hidden}

EraseMEjimspam_OUTspamTakeThisOuTjpes.com

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's


2000\10\09@104604 by Dan Michaels

flavicon
face
Tony Nixon wrote:

>Is there any difference in the 16F876 against the 16F873 apart from
>ROM/RAM size?
>
>Ever since I've changed from the F873 to F876 I can't get the programmer
>project to work.
>

Config word?

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's


2000\10\09@112840 by Jim Robertson

flavicon
face
At 04:59 PM 09/10/00 +1100, you wrote:


The memory MAP of the RAM is different.

If you accidently were in RAM page 2 it would not matter on the 16F873
as this page wraps to page 0. It certainly would on the 16F876 (unless it
was the last 16 bytes as they are common to RAM page 0.) Maybe you
have not cleared both RAM page select bits or you are accidently setting
one in your code. Are you using any of the SFR in page 3 and not
switching back to page 0? This is were I would look.

This would fit the problem you have described, works on a 16F873 but
not on a 16F876, it also explains why your led test works. If you
were in page 3 RAM most of the SFRs are common to page 0 (but NOT PORT A
or TRISA.)

BTW. There are no differences in the config word.


-Jim



{Quote hidden}

Regards,

Jim Robertson
NEWFOUND ELECTRONICS
Email: @spam@newfoundKILLspamspampipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's


2000\10\09@183702 by Tony Nixon

flavicon
picon face
Dan Michaels wrote:

> Config word?

YEP!

And speaking of LVP bits ....

After a weekend of mucking around it struck me about 10PM last night.

RB0 - RB3 used for 4 bit LCD data and RB3 was set for LV programming.

[embarrassment mode on]

As it turns out, I was my owm enemy and forgot to modify a case
statement in my programmer software after I added the 870/1/2 chips.
Consequently, 874 876 and 877 were affected, and wouldn't you know it,
this particular part of the code looked after the LVP bit in the fuse
data. On screen it looked disabled, but behind the scenes it was still
enabled, and because the LVP data never actually changed from '1', it
verified ok.

I couldn't think past the fact that I had new code, new chips and a new
PCB so it had to be there somewhere.


That's twice the RB3/LVP bit caught me with some obscure bug, so I'll
pay a lot more attention to it in the future.

--
Best regards

Tony

ICmicro's
http://www.picnpoke.com
KILLspamsalesKILLspamspampicnpoke.com

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's


2000\10\09@212032 by Dan Michaels

flavicon
face
Tony Nixon wrote:
>Dan Michaels wrote:
>
>> Config word?
>
>YEP!
>
>And speaking of LVP bits ....
>
>After a weekend of mucking around it struck me about 10PM last night.
>
>RB0 - RB3 used for 4 bit LCD data and RB3 was set for LV programming.
>

Funny, I have been trying to follow what everybody has been
saying about what you have to do with the LVP bit and RB3 to get
the '87x chips to program, but I've been using my old circa 1995
[before the days of '87x] EPIC to program '874 and '873 chips.
It doesn't know anything about RB3 - pin is floating.

It programs at 13v, and works the 1st time and every time
thereafter. I keep wondering what all the stew is about. This
isn't ICSP, but seems to me you can use your programmer the 1st
time, without much worry, and ICSP after that. Am I missing
something?

- danM

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads




2000\10\09@215026 by Jim Robertson

flavicon
face
At 04:59 PM 09/10/00 +1100, you wrote:

>Another thing I noticed, is that I program the PIC programmer code into
>my usual programmer and the 876's won't work for at least 30 seconds
>again after powering down. I can cycle the power immediately with the
>873's with exactly the same code and fuse settings and it works
>instantly everytime.

Tony, is this problem also fixed? I am still being asked about weird 16F876
behavour after programming that has surfaced all of a sudden.

Are your 16F876 parts working normally?

-Jim


{Quote hidden}

Regards,

Jim Robertson
NEWFOUND ELECTRONICS
Email: spamBeGonenewfoundspamBeGonespampipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads




2000\10\09@221806 by Tony Nixon

flavicon
picon face
Jim Robertson wrote:
>
> At 04:59 PM 09/10/00 +1100, you wrote:
>
> >Another thing I noticed, is that I program the PIC programmer code into
> >my usual programmer and the 876's won't work for at least 30 seconds
> >again after powering down. I can cycle the power immediately with the
> >873's with exactly the same code and fuse settings and it works
> >instantly everytime.
>
> Tony, is this problem also fixed? I am still being asked about weird 16F876
> behavour after programming that has surfaced all of a sudden.
>
> Are your 16F876 parts working normally?
>
> -Jim
>

Hi Jim,

I suspect it may have been the RB3 pin interacting with programmer
circuitry somehow.

However, after fixing the problem the board starts again within a 2 sec
shutdown. I don't have a reset circuit on MCLR and have a 220uF on the
power side of the reg, so I would say it is fairly normal.

I am going to start some heavy programming with this chip from tonight
which will also make use of the internal EEPROM so I will see how it
performs.

I have 20P versions and will be running at 4MHz.

--
Best regards

Tony

ICmicro's
http://www.picnpoke.com
TakeThisOuTsalesEraseMEspamspam_OUTpicnpoke.com

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads




2000\10\09@223528 by Dan Michaels

flavicon
face
Tony wrote:
.........
>
>However, after fixing the problem the board starts again within a 2 sec
>shutdown. I don't have a reset circuit on MCLR and have a 220uF on the
>power side of the reg, so I would say it is fairly normal.
>

Tony, that's an awfully big cap. Maybe you should check and
be sure Vcc comes up fast enough [5v/100msec, I think] that the
chip performs reset/startup properly. Maybe your poor little
wallwart has its pants full.

- danM

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads




2000\10\09@223740 by Dan Michaels

flavicon
face
I wrote:
.........
Maybe your poor little
>wallwart has its pants full.


uh, "hands" full.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads




2000\10\09@225821 by Tony Nixon

flavicon
picon face
Dan Michaels wrote:

> Tony, that's an awfully big cap. Maybe you should check and
> be sure Vcc comes up fast enough [5v/100msec, I think] that the
> chip performs reset/startup properly. Maybe your poor little
> wallwart has its pants full.
>
> - danM


Got it hooked up to the 3 phase with automotive jump start cables ;-)

I chose a slightly larger cap because of the real world interface on the
programmer board. I haven't had any problems reported as yet and there
are quite a few around.


--
Best regards

Tony

ICmicro's
http://www.picnpoke.com
RemoveMEsalesspamTakeThisOuTpicnpoke.com

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads




2000\10\09@230730 by Tony Nixon

flavicon
picon face
> Dan Michaels wrote:
>
> > Tony, that's an awfully big cap. Maybe you should check and
> > be sure Vcc comes up fast enough [5v/100msec, I think] that the
> > chip performs reset/startup properly. Maybe your poor little
> > wallwart has its pants full.

I just looked at the startup on the storage CRO. 0 - 5V in about 35mS.
There's a bit of a bow in the center.


--
Best regards

Tony

ICmicro's
http://www.picnpoke.com
salesEraseMEspam.....picnpoke.com

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:","[SX]:","[AVR]:" =uP ONLY! "[EE]:","[OT]:" =Other "[BUY]:","[AD]:" =Ads




2000\10\10@084810 by Andy Shaw

flavicon
face
Folks, I've been sort of keeping an eye on this thread mainly because I'm
just about to switch over to using 87x for some projects. Up until now I've
been working with the MPLAB ICE 2000 (nice bit of kit). However I'm just
about to start programming actual parts. So the question is am I going to
have any odd problems here. I use the Picstart Plus. So far using 16C71x
I've had no problems and things developed using the ICE have worked first
time when put into an actual device. But all this talk of LVP stuff is
making me nervous.

So should I expect problems, what can I do to avoid them?

Thanks
Andy

{Quote hidden}

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics




2000\10\10@093634 by Olin Lathrop

flavicon
face
> Up until now I've
> been working with the MPLAB ICE 2000 (nice bit of kit). However I'm just
> about to start programming actual parts. So the question is am I going to
> have any odd problems here.

I'm working on two 16F876 projects right now and others in this family in
the past.  When it worked with the ICE, it has so far always worked on the
real thing.  Keep in mind that the ICE is the real thing (well, almost).
Your code is actually running on a special part with more stuff bonded out
so the rest of the ICE circuitry can get at it.  You will probably have no
problems, especially if you set up the ICE to use target board power and
clock.

The only problem I have run into with the ICE and 16F87x parts is when
trying to access the program memory as data.  You can't step thru a program
memory read, or the whole system will lock up and complain about stack
overflow.  You can run thru program memory reads, but they take *much*
longer than the real thing.  One of my projects reads some audio data in
program memory and chugs it out via PWM in the interrupt routine.  This
appeared not to work at all.  Eventually I realized that the ICE was running
so slowly that it looked broken, and that the PWM also got interrupted
somehow during a program memory read.  I programmed a real chip with the
same code and everything worked fine.

All around, the ICE-2000 is a nice piece of work with decent support with
everything from one vendor.  Quite a bargain at $1,500.  It doesn't take
much time saved to get that back.


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

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics




2000\10\10@095303 by Olin Lathrop

flavicon
face
> The only problem I have run into with the ICE and 16F87x parts is when
> trying to access the program memory as data.  You can't step thru a
program
> memory read, or the whole system will lock up and complain about stack
> overflow.  You can run thru program memory reads, but they take *much*
> longer than the real thing.  One of my projects reads some audio data in
> program memory and chugs it out via PWM in the interrupt routine.  This
> appeared not to work at all.  Eventually I realized that the ICE was
running
> so slowly that it looked broken, and that the PWM also got interrupted
> somehow during a program memory read.  I programmed a real chip with the
> same code and everything worked fine.

One more gotcha I forgot to mention.  The 16F87x manual (section 4.5, page
44) shows two NOP instructions after the BSF EECON1, RD instruction to start
a program memory read.  The comment reads "memory is read in the next two
cycles after BSF EDCON1, RD".  The description text reads "The data is
available in the EEDATA and EEDATH registers after the second NOP
instruction".  After reading this and the rest of the description, I figured
I would use the two cycles after the read start and before the data is
available to do something else unrelated.  THIS DOES NOT WORK.  It appears
the two instructions following the read start are not just to wait for the
data to be available, but are actually ingnored by the processor.  In other
words, they need to be NOPs, not any arbitrary code that doesn't use EEDATA
or EEDATH.

I'm guessing that the processor keeps the PC chugging along as it uses the
cycles to read program memory at an address other than that indicated by the
PC.  Probably NOP instructions are forced into the opcode decoder, or it is
somehow disabled by other means.  It appears that the two words following
the read start are never fetched.  I don't have a problem with this mode of
operation, but Microchip should have made this more clear.  I did notice
afterwards that the same NOPs following a program memory write are commented
"Instructions here are ignored by the microcontroller".


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

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics




2000\10\10@181719 by Tony Nixon

flavicon
picon face
Andy Shaw wrote:
>
> Folks, I've been sort of keeping an eye on this thread mainly because I'm
> just about to switch over to using 87x for some projects. Up until now I've
> been working with the MPLAB ICE 2000 (nice bit of kit). However I'm just
> about to start programming actual parts. So the question is am I going to
> have any odd problems here. I use the Picstart Plus. So far using 16C71x
> I've had no problems and things developed using the ICE have worked first
> time when put into an actual device. But all this talk of LVP stuff is
> making me nervous.
>
> So should I expect problems, what can I do to avoid them?
>
> Thanks
> Andy

I have just been playing with F parts that I have recently purchased.

LVP = 1

(As it would be anyway if your programmer erases the chip before
programming)

If RB3 is held low HV programming works.
If RB3 is held high HV programming does not work.

So HV mode does not appear to override LV mode as it seems that the
state of RB3 is the deciding factor.


If you don't want LVP mode make sure you disable it by clearing the LVP
fuse. Then PORTB is a normal 8 bit port. Otherwise RB3 is not useable as
an IO pin. If you are not aware of this, you may lead yourself down a
needless time consuming bug path.


Wouldn't it be nice to put the LVP pin somewhere else, why in the middle
of a PORT?

IF HV mode is entered while raising MCLR to VPP while RB6/7 are low, why
not have LV mode entered while raising MCLR to VCC while RB6/7 is high,
or some other combination. Makes more sense to me.



--
Best regards

Tony

ICmicro's
http://www.picnpoke.com
RemoveMEsalesspam_OUTspamKILLspampicnpoke.com

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics




2000\10\10@230144 by Jim Robertson

flavicon
face
At 09:16 AM 11/10/00 +1100, you wrote:
>
>I have just been playing with F parts that I have recently purchased.
>
>LVP = 1
>
>(As it would be anyway if your programmer erases the chip before
>programming)
>
>If RB3 is held low HV programming works.
>If RB3 is held high HV programming does not work.
>
>So HV mode does not appear to override LV mode as it seems that the
>state of RB3 is the deciding factor.

So Tony, why don't the chips program in any case? They are still in LV mode
(as inferred by you) and everything else is the same as for HV mode, right?

Exactly what would be achieved of the either mode "overrode" the other when
the conditions of operation are fulfilled for both modes and the programming
algorithm is the same in each case?


Regards,

Jim Robertson
NEWFOUND ELECTRONICS
Email: RemoveMEnewfoundTakeThisOuTspamspampipeline.com.au
http://www.new-elect.com
MPLAB compatible PIC programmers.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics




2000\10\11@044436 by Alan B. Pearce

face picon face
>So Tony, why don't the chips program in any case? They are still in LV mode
>(as inferred by you) and everything else is the same as for HV mode, right?

My understanding is that Programming Mode is set by  an AND of HV on the MCLR pin with (RB3 low AND LVP true). I think I have the logic of that correct. In essence if LVP mode is set, then RB3 has to be LOW to program, wether doing it by low voltage or high voltage.
--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.




More... (looser matching)
- Last day of these posts
- In 2000 , 2001 only
- Today
- New search...