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'In Circuit Serial Programming (and apologies)'
1996\03\21@042649 by Dennis Velthuis

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Hello.

First, I am terribly sorry of the rude accidental posting I did.
I was NOT aware of the fact that a reply to a message on the piclist would
arrive on the pic-list.
Hereby I want to apologise myself to anyone I have offended by my 'junk' mail.
Again, sorry. I wish I could turn back the clock.

Now to the topic...

I want to be able to do some in circuit serial (re)programming of a
circuit I have. In general, I want to experiment with the fact that a '84 can
be programmed whilst in the target circuit.
The circuit consists of a 16c84, vdd is directly connected to vpp.

Now my question is, is this possible? I personally don't think so
'coz vdd needs to be 5v and vpp needs to be 13.5v.
I think I will blow it up while trying to program this circuit.
But maybe not, I don't want to throw away my picstart 16b, nor the '84.

Is it possible with extra circuitery?
Should the circuit contain an extra resistor between vdd and vpp and if yes
what value?

How long can the programmer to '84 cable be in general?
I want to be able to use quite a long cable (1 meter), are there any things
I should be aware of?

I was also wondering, has the picstart16b1 the ability to do in circuit
serial programming or do I need a special programmer?
If yes, what kits are out there with this ability? (commercial and diy)

Many questions, I hope one of you specialists can help me.

Thanks in advance.







--
****************************************************************************
*             -= Dennis Velthuis =-    -= spam_OUTdenvTakeThisOuTspamhtsa.hva.nl =-              *
*                 -= Raving His Way Into Tha Future ;) =-                  *
*                   -= http://htsa.htsa.hva.nl/~denv =-
*     -= U Have The Right to Exchange Information, So Use This Right! =-   *
****************************************************************************

1996\03\21@053656 by Newfound Electronics

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>Hello.
Cut..
>Again, sorry. I wish I could turn back the clock.
>
Yer. I know the feeling.

{Quote hidden}

Yes. The value can be 4K7-22K. 10K is good. Some people use a diode but a
resistor is better as it allow ESD to discharge. ESD on the Vpp pin CAN
scramble the memory!

>
>How long can the programmer to '84 cable be in general?
>I want to be able to use quite a long cable (1 meter), are there any things
>I should be aware of?

I meter long cable probably won't cause to many problems but this is a
matter I'm not expert on. There is nothing extra to consider just because
you are actually programming a chip. The usual data comms considerations
apply. I'm to uneducated to say much more.

>I was also wondering, has the picstart16b1 the ability to do in circuit
>serial programming or do I need a special programmer?
>If yes, what kits are out there with this ability? (commercial and diy)

The PICSTART 16B used the serial method of programming (I think!) BUT this
is not necessarily the same as ISP. Maybe you can experiment and get the
PICSTART to program in-system.

It should be possible. Just don't load RB6 and RB7 on the target.

I recommend you start with the 16C84 in a bare socket (and the Vdd-Vpp
resistor) and bring GND (5), Vdd (15), Vpp (4)  RB6 (13) and RB7(14) across
to it. Get it working in the socket first to verify the use of the serial
program method and correct wiring THEN transpose to you target. This way you
can track where problem occur. Pin numbers in () are for the 16C84.

There are many kit programmers that will program the 16C84 in-system but I
feel you should be able get the PICSTART to do what you want.
>
>Many questions, I hope one of you specialists can help me.

Me, a "specialist?" A title at last?!
>
>Thanks in advance.
>

Regards and good luck,

Jim

1996\03\21@060013 by Dermot

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On Thu, 21 Mar 1996, Newfound Electronics wrote:

> >Should the circuit contain an extra resistor between vdd and vpp and if yes
> >what value?
>
> Yes. The value can be 4K7-22K. 10K is good. Some people use a diode but a
> resistor is better as it allow ESD to discharge. ESD on the Vpp pin CAN
> scramble the memory!
>
Hi,

While it will limit any current flow to a fairly harmless level, a
resistor alone will not prevent the Vpp voltage appearing on the 5 volt
Vdd supply line. I prefer to use a diode and resistor in series. The
programmer should hold Vpp to ground before applying the actual Vpp in
programming mode thus providing an ESD path.

Regards,
_________________________________________________________________________
 __     __   ___             __   ____  <>  Electrical Engineering Dept.
/  \   /_   /__/  /\  /\    /  /   /    <>    University of Bradford
/___/  /__  /  \  /  \/  \  /__/   /     <>            England

1996\03\21@062749 by Newfound Electronics

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>On Thu, 21 Mar 1996, Newfound Electronics wrote:
>
>> >Should the circuit contain an extra resistor between vdd and vpp and if yes
>> >what value?
>>
>> Yes. The value can be 4K7-22K. 10K is good. Some people use a diode but a
>> resistor is better as it allow ESD to discharge. ESD on the Vpp pin CAN
>> scramble the memory!
>>
>Hi,
>
>While it will limit any current flow to a fairly harmless level, a
>resistor alone will not prevent the Vpp voltage appearing on the 5 volt
>Vdd supply line. I prefer to use a diode and resistor in series. The
>programmer should hold Vpp to ground before applying the actual Vpp in
>programming mode thus providing an ESD path.

Dermot,

At no stage should there be Vpp applied without Vdd. It is the presence of
Vdd that stops Vpp appearing on the Vdd pin. I would be VERY concerned if
any programmer applied Vpp without Vdd.

Regarding ESD. While the programmer may hold Vpp at ground, what about when
it is not connected? This is when ESD "scrambling" can occur. I know it less
likely if the usual preventative measures are taken, BUT I know it has
happened and it appears to happen at ESD levels that ordinarily wouldn't
harm the rest of the componentry. IMHO the resistor method has no drawbacks
and does serve to prevent such occurences. I can see only positives for it
myself. However, many people do use the diode without to many problems.

BTW  The "victim" in the case I know of had to reprogram 100 16C84 based
boards again. Ouch!

Regards

Jim

1996\03\21@084559 by Bill Cornutt

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----------

>I want to be able to do some in circuit serial (re)programming of a
>circuit I have. In general, I want to experiment with the fact that a '84 can
>be programmed whilst in the target circuit.


While I can not answer your question, or because I can not
answer your question, I have an alternative for you.

The Basic Stamp does what you want.  It is a pic programmed
with an interperter.  The basic tokens are storred in serial
eeprom.  To program a '84' for such a function may not be
practical because of development time and/or memory,

But the concept may be a good one to use.

The 64 bytes of eeprom data could hold I/O pin configuations
and/or data constants.  Also the data eeprom could contain tokens
to control program flow.  (a very high level interperter?)

So if you wish to have just a reconfiguable program or I/O, then
the only cost would be the serial interface program and its I/O pins.

I do not know for what purpose you wish to reprogram the PIC, but
the concept is interesting.  I have written a program for the IBM PC
that is a platform for testing methods of solving mazes.  The program
accepts commands such as "go right", "turn left", and "test foward".
The program returns a true if the command was excuited or a false if
there was an obstruction in the way.  I then added a celluar automata
routine with a eight by eight matrix program to run the maze.  This
became a self learning program for the "maze runner" and had good
results.  Could this "self learning" feature be implimented on a PIC?

Bill C.

1996\03\21@092850 by Norm Cramer

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{Quote hidden}

When I tried this, I had problems getting the circuit to program correctly.
I added a jumper that connects the Vdd of the chip to the rest of the
circuit.  When I need to program, I remove the jumper before attaching
the programmer.  This has worked so far.  I currently don't have anything
attached to the programming clock and data pins (RB6,RB7) in my circuit.  I do
have the diode from circuit Vdd to the MCLR pin to protect the rest of the
circuit while programming.  BTW I am using the ITU PIC-1 programmer but if
your programmer uses serial programming, the same should apply.

>
>>
>>How long can the programmer to '84 cable be in general?
>>I want to be able to use quite a long cable (1 meter), are there any things
>>I should be aware of?

The signal is serial but the voltage levels are not the same as
EIA-232 (AKA RS-232).  The main concerns I would have is voltage drop for
a 1m run and cross talk from the clock and data signals.  Cross talk can
be minimized by using sheilded twisted pair (STP) cable but you may not be
able to compensate for voltage drop.  Try it and see.

>>I was also wondering, has the picstart16b1 the ability to do in circuit
>>serial programming or do I need a special programmer?
>>If yes, what kits are out there with this ability? (commercial and diy)

Don't know if PICSTART can do serial programming but the PIC-1 from ITU can.
If you can wirewrap the programmer, buy the plans and software package only
since the circuit is quite simple.  I bought the full kit and am quite pleased
with it.  ITU even responded to my sugesstions to improve the kit.

>
>I recommend you start with the 16C84 in a bare socket (and the Vdd-Vpp
>resistor) and bring GND (5), Vdd (15), Vpp (4)  RB6 (13) and RB7(14) across
>to it. Get it working in the socket first to verify the use of the serial
>program method and correct wiring THEN transpose to you target. This way you
>can track where problem occur. Pin numbers in () are for the 16C84.
>

This is great advice.  When my first attempts to program in circuit failed,
I had to go back and take things off until I found the problem.  Would have
been much smarter to approach it this way.

BTW in circuit programming is the only way to go.  I can program the chip, test
it find my bugs and reprogram it in a few mins.


Hope this helps,

Norm
.....cramerKILLspamspam@spam@dseg.ti.com

1996\03\21@095350 by Newfound Electronics

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>>Yes. The value can be 4K7-22K. 10K is good. Some people use a diode but a
>>resistor is better as it allow ESD to discharge. ESD on the Vpp pin CAN
>>scramble the memory!
>
>When I tried this, I had problems getting the circuit to program correctly.
>I added a jumper that connects the Vdd of the chip to the rest of the
>circuit.  When I need to program, I remove the jumper before attaching
>the programmer.  This has worked so far.  I currently don't have anything
>attached to the programming clock and data pins (RB6,RB7) in my circuit.  I do
>have the diode from circuit Vdd to the MCLR pin to protect the rest of the
>circuit while programming.  BTW I am using the ITU PIC-1 programmer but if
>your programmer uses serial programming, the same should apply.

Norm,

Have you tried reducing or eliminating the 100R resistor (R11 on my ITU
programmer) This might fix you problem and eliminate the need for the Vdd
jumper. This 100R resistor was discussed a month or two ago on the piclist.
>
>>>I was also wondering, has the picstart16b1 the ability to do in circuit
>>>serial programming or do I need a special programmer?
>>>If yes, what kits are out there with this ability? (commercial and diy)
>
>Don't know if PICSTART can do serial programming but the PIC-1 from ITU can.
>If you can wirewrap the programmer, buy the plans and software package only
>since the circuit is quite simple.  I bought the full kit and am quite pleased
>with it.  ITU even responded to my sugesstions to improve the kit.

Yes, the new PCB looks very impressive and the ITU programmer has been well
supported.

{Quote hidden}

Regards

Jim

1996\03\21@104345 by Norm Cramer

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>>
>>When I tried this, I had problems getting the circuit to program correctly.
>>I added a jumper that connects the Vdd of the chip to the rest of the
>>circuit.  When I need to program, I remove the jumper before attaching
>>the programmer.  This has worked so far.  I currently don't have anything
>>attached to the programming clock and data pins (RB6,RB7) in my circuit.  I do
>>have the diode from circuit Vdd to the MCLR pin to protect the rest of the
>>circuit while programming.  BTW I am using the ITU PIC-1 programmer but if
>>your programmer uses serial programming, the same should apply.
>
>Norm,
>
>Have you tried reducing or eliminating the 100R resistor (R11 on my ITU
>programmer) This might fix you problem and eliminate the need for the Vdd
>jumper. This 100R resistor was discussed a month or two ago on the piclist.

I'll check, I remember that I did not install one of the resistors but don't
remember wich one.  I'll see if it was R11.  Thanks for the tip.

Norm

1996\03\21@131856 by John Payson

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> >How long can the programmer to '84 cable be in general?
> >I want to be able to use quite a long cable (1 meter), are there any things
> >I should be aware of?
>
> I meter long cable probably won't cause to many problems but this is a
> matter I'm not expert on. There is nothing extra to consider just because
> you are actually programming a chip. The usual data comms considerations
> apply. I'm to uneducated to say much more.

The cable length is limitted primarily by:

[1] What speed do you send the data; the lower the speed the longer the cable
   can be.

[2] If you want to RUN the processor with the ISP cable hooked up [often very
   handy during development], what sort of protection is there on /MCLR to
   prevent spontaneous glitches?

1996\03\21@163553 by Don McKenzie

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On Thu, 21 Mar 1996, Dennis Velthuis wrote:

> Hello.
>
> First, I am terribly sorry of the rude accidental posting I did.
> I was NOT aware of the fact that a reply to a message on the piclist would
> arrive on the pic-list.
> Hereby I want to apologise myself to anyone I have offended by my 'junk' mail.
> Again, sorry. I wish I could turn back the clock.

I'm sure the list understands now what really took place Dennis. Yes put
it behind you. Take Andy's advice and ignore/delete all SPAMS and they will
stop.

{Quote hidden}

My 84 programmer uses a bulldozer approach for this task. It hardware
switches everthing. It may not suit your setup but the circuit can be
examined at http://www.labyrinth.net.au/~donmck
This may give you some ideas.

I have often thought of getting one of those cheap DB-25 two way switch
boxes and wiring it up as follows:

Connect an 18 pin socket to a DB-25 plug so it can accept the 84 device
and plug this into the common leg of the switch.
Crimp two flat ribbon cables with DIP headers one end and DB-25's the
other. One cable connects to your target, the other to your Picstart or
any programmer. You now have a load/run switch.

Cables, I keep them as short as possible. For me that means 6 inches.

Hope this helps Don...

Don McKenzie .....donmckKILLspamspam.....tbsa.com.au
DonTronics Tullamarine, Australia
http://www.labyrinth.net.au/~donmck

PIC Programmers starting at $15US, BS1/2 & Alternatives 18/28 PIC proto
PicoSaurus, the 40 pin ETI PIC Basic with 8K EEPROM Free Windows Dev Sys

1996\03\22@080500 by Derrick Early

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Dennis,

With a few well place diodes you should not have any trouble with
doing an in circuit programming.  You may want to make sure that
your oscillator is off while programming.  I had trouble with
it incrementing the program locations.  So instead of starting a
0x0000, the program would load randomly from 0x0001 to 0x0010.
Once I disabled the oscillator, everything worked great.  I think
that you should still be able to use your picstart.  If you can't,
you could always build David Taite's programmer.

Good luck.

Yours,
--
Derrick Early
EraseMEearlyspam_OUTspamTakeThisOuTfinite.nrl.navy.mil

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