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'In circuit programming'
1996\10\09@111722 by Conor O'Rourke

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Hi guys [ok,ok and gals, and plas :-) ],

Just a quick question - I'm designing a small board that will
plug into an ISA slot on a PC. It's a simple enough project except
for one minor detail - I want to be able to program the PIC while
it's in the slot...
Should be easy enough - the interfacing is trivial, but the problem
is Vpp. This has to be 12-14 volts, right? But when you use the
12V available from the ISA bus you get a problem - there will
be at least one diode drop or transistor drop (or in my design, both!)
in the circuit in order to switch the Vpp in and at the same time
not blow your 5V line. This brings the 12V below the required Vpp.
It's a pain to use an external power supply and you have to be a
lot more careful about gating...

Has anyone encountered this problem or have a simple solution to it?

Thanks muchly,

Conor

1996\10\09@113015 by liebchen

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Conor O'Rourke wrote:
>
> Should be easy enough - the interfacing is trivial, but the problem
> is Vpp. This has to be 12-14 volts, right? But when you use the
> 12V available from the ISA bus you get a problem - there will
> be at least one diode drop or transistor drop (or in my design, both!)

Hi Conor,

I'm not sure how much current is needed for Vpp (I think you use a
16C84?),
but perhaps you can connect the 12 V of the PC with a sufficiently large
resistor
to the Vpp line. No current - no drop.

Hope it helps a bit,

Wolfram

PS: Why don't you use MOSFETs to switch? No voltage drop.

W.

--

+------------------------------------------------+
! Wolfram Liebchen, Forschungsinstitut fŸr Optik !
! spam_OUTliebchenTakeThisOuTspamffo.fgan.de                    !
+------------------------------------------------+

1996\10\09@141411 by vador Eduardo Tropea (SET)

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Hi Conor, here SET:

>Hi guys [ok,ok and gals, and plas :-) ],

>Just a quick question - I'm designing a small board that will
>plug into an ISA slot on a PC. It's a simple enough project except
>for one minor detail - I want to be able to program the PIC while
>it's in the slot...
>Should be easy enough - the interfacing is trivial, but the problem
>is Vpp. This has to be 12-14 volts, right? But when you use the
>12V available from the ISA bus you get a problem - there will
>be at least one diode drop or transistor drop (or in my design, both!)
>in the circuit in order to switch the Vpp in and at the same time
>not blow your 5V line. This brings the 12V below the required Vpp.
>It's a pain to use an external power supply and you have to be a
>lot more careful about gating...

>Has anyone encountered this problem or have a simple solution to it?

Some time ago I made an EPROM programmer for PC and I see this problem, you
can:
1) Use an external power supply attached to your board.
2) Use an step-up converter (DC-DC), for example a 78S40 switching chip.
3) Use a simple voltage doubler with 2 diodes and 2 capacitors, this solution
is the simplest but you'll be loosing the 70% of the power, that's isn't a
problem in a PC where the 12V supply can drain 8 A (Not to one slot!!).

bye SET.

********************************************************************************
Salvador Eduardo Tropea (SET) - .....salvadorKILLspamspam@spam@inti.edu.ar
Work: INTI (National Institute of Industrial Technology) Sector: ICE
(Electronic Control & Instrumentation)
Post (Home): Curapaligue 2124 - Caseros (1678)- Buenos Aires - Argentina

1996\10\09@151447 by SLIWINSKIA

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Conor O'Rourke wrote:
>
> Should be easy enough - the interfacing is trivial, but the problem
> is Vpp. This has to be 12-14 volts, right? But when you use the
> 12V available from the ISA bus you get a problem - there will
> be at least one diode drop or transistor drop (or in my design, both!)

You could try a dc-dc converter.  Even a ~+5V to +12V one will get you
the margin you need.  Just use the ISA +5V as the ground on the converter,
and the ISA +12V as the input voltage.  You'll get +17V relative to ground.

There are lots of those things running around at surplus places, and on old
network cards.  You might also try using a MAX232 if you can't find a cheap
converter.

-- Aaron Sliwinski
sliwinskia-cos3spamKILLspamkaman.com

1996\10\09@182134 by bruce

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In-Reply-To: <.....01IAG1GW2WLC8WWUQXKILLspamspam.....ccvax.ucd.ie>
> Just a quick question - I'm designing a small board that will
> plug into an ISA slot on a PC. It's a simple enough project except
> for one minor detail - I want to be able to program the PIC while
> it's in the slot...
> Should be easy enough - the interfacing is trivial, but the problem

Conor,

Could I follow on from your question and ask you how you are interfacing
the PIC to the ISA bus. I have a need to pass a number of bytes of data
to and from a PIC over the ISA bus and am struggling about how to start
the design.

I am quite happy about buffering the bus and address decoding to the
ubiquitous 0x300 etc but am not certain how to arrange for an I/O write
to pass data to the PIC and an I/O read vice versa. Can you give me any
pointers?

Bruce

1996\10\09@194217 by Robert Ct

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At 03:04 PM 10/09/96 +0300, you wrote:
>Hi Conor, here SET:

>Some time ago I made an EPROM programmer for PC and I see this problem, you
>can:
>1) Use an external power supply attached to your board.
>2) Use an step-up converter (DC-DC), for example a 78S40 switching chip.
>3) Use a simple voltage doubler with 2 diodes and 2 capacitors, this solution
>is the simplest but you'll be loosing the 70% of the power, that's isn't a
>problem in a PC where the 12V supply can drain 8 A (Not to one slot!!).
>
>bye SET.
>
Option #3 is not an option...   A voltage doubler like this works on AC, not DC!
...
Robert

1996\10\09@230942 by Jason F. Penn
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>
>Has anyone encountered this problem or have a simple solution to it?
>

Wild guess. I haven't tried this.

How about using (p-channel?) FETs for switching between +12 and +5?
The 'on' resistance might be low enough. The 'on' resistance of a
4066 CMOS switch might even be ok.

Anybody care to beat this idea down?

73 de Jason

P.S. I've been using the CCS PIC C compiler for 16C74 work for the
past few days. I like it. It works. It lets me concentrate on the
task at hand without distractions from PIC assembler trivia.
The code generated looks pretty reasonable, but a bit non-obvious
a first glance of the .LST file. It compiles my C versions faster
than MPASM assembles the equivalent ASM versions. Go figure.

--

                     Jason F. Penn N9RPT | EraseMEpennspam_OUTspamTakeThisOuTmailbag.com
  Whenever I want to find something, it's always in the last place I look.

1996\10\09@233152 by John Payson

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> How about using (p-channel?) FETs for switching between +12 and +5?
> The 'on' resistance might be low enough. The 'on' resistance of a
> 4066 CMOS switch might even be ok.
>
> Anybody care to beat this idea down?

I have seen 4066 switches used in similar applications; unfortunately, I
am not aware of anyone making a 74HCT4066--that would be a really useful
part [for those uninitiated, a 4066 or 74HC4066 is a digital switch which
may be used to switch any signal or voltage between its Vss (ground) and
VDD (supply) rails.  Since the supply rail may be up to +15v, the device
may be used to conveniently switch programming voltage and other such
signals.  Unfortunately, the switching threshhold for "standard" CMOS or
74HC parts is VDD/2; if VDD is 12 volts this means the switching thresh-
hold is at least 6 volts--not something a normal port can deal with.  The
74HCT series of parts switches at around two volts independent of supply
and would be ideal in this application.]

Actually, this gets back to a question I was asking before: what is the
maximum allowable voltage on the RA4 pin (16C84 etc.)?  The documentation
says there's no diode to VDD, but it doesn't grand permission to go above
VDD even so.

1996\10\10@041758 by mike

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picon face
In message  <01IAG1GW2WLC8WWUQXspamspam_OUTccvax.ucd.ie> @spam@PICLISTKILLspamspamMITVMA.MIT.EDU writes:
> Hi guys [ok,ok and gals, and plas :-) ],
>
> Just a quick question - I'm designing a small board that will
> plug into an ISA slot on a PC. It's a simple enough project except
> for one minor detail - I want to be able to program the PIC while
> it's in the slot...
> Should be easy enough - the interfacing is trivial, but the problem
> is Vpp. This has to be 12-14 volts, right? But when you use the
> 12V available from the ISA bus you get a problem - there will
> be at least one diode drop or transistor drop (or in my design, both!)
> in the circuit in order to switch the Vpp in and at the same time
> not blow your 5V line. This brings the 12V below the required Vpp.
> It's a pain to use an external power supply and you have to be a
> lot more careful about gating...
>
Conor,


From experience, the PCs 12V rail is not very useful. The PC to PC
variation is too high.

I a previous job designing PCMCIA FLASH card readers for we derived
Vpp from the Vcc using a switcher IC. Both Maxim and LT both do
chips specific to programming flash memory which would work well
in your application.


Regards,



Mike Watson

1996\10\10@062143 by Andy Errington

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>I'm designing a small board that will
>plug into an ISA slot on a PC. ...  I want to be able to program the
>PIC while
>it's in the slot.
>Should be easy enough - the interfacing is trivial, but the problem
>is Vpp. This has to be 12-14 volts ... But ... there will
>be at least one diode drop or transistor drop (or in my design, both!)
> ... This brings the 12V below the required Vpp.

Hi Conor,

the solution is to experiment.  Firstly I assume that this design is not
for a commercial device (if it is then of course you must be sure to
adhere rigidly to the spec's, and you can ignore the rest of this
message).  It is important to note that the Vpp voltage is not actually
used to power the programming process, it is simply the presence of a
voltage at this level that sets the '84 into program mode.  The actual
programming voltage for the EEPROM is internally generated.

Bearing this is mind just what voltage will trigger the device into
program mode?  Is 11.4V enough, or is your PC's 12V line actually 12.6V?
Try it and see.

I know this thread is now two days old, and so is ancient history as far
as the original problem is concerned.  However, if you like I will have
a go back at home, and try programming an '84 with different voltage
levels on the ^MCLR pin, and let you know how I get on.

As I said above however, if this is a commercial design you will want to
ensure that you meet the specifications exactly, and you must also be
able to vary Vdd to perform verification to Microchip's specification.

Andy (the other one)
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1996\10\10@064055 by Jacob Blichfeldt

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part 0 1150 bytes
>I have seen 4066 switches used in similar applications; unfortunately, I
am not aware of anyone making a 74HCT4066--that would be a really useful
part [for those uninitiated, a 4066 or 74HC4066 is a digital switch which
may be used to switch any signal or voltage between its Vss (ground) and
VDD (supply) rails.  Since the supply rail may be up to +15v, the device
may be used to conveniently switch programming voltage and other such
signals.  Unfortunately, the switching threshhold for "standard" CMOS or
74HC parts is VDD/2; if VDD is 12 volts this means the switching thresh-
hold is at least 6 volts--not something a normal port can deal with.  The
74HCT series of parts switches at around two volts independent of supply
and would be ideal in this application.]

>Actually, this gets back to a question I was asking before: what is the
maximum allowable voltage on the RA4 pin (16C84 etc.)?  The documentation
says there's no diode to VDD, but it doesn't grand permission to go above
VDD even so.


As I wrote in another reply, the 'absolute maximum ratings' state 14V on RA4,
but as you write there's no 'design ratings'.

1996\10\10@082822 by vador Eduardo Tropea (SET)

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Hi all:

>>Hi Conor, here SET:
>>Some time ago I made an EPROM programmer for PC and I see this problem, you
>>can:
>>1) Use an external power supply attached to your board.
>>2) Use an step-up converter (DC-DC), for example a 78S40 switching chip.
>>3) Use a simple voltage doubler with 2 diodes and 2 capacitors, this solution
>>is the simplest but you'll be loosing the 70% of the power, that's isn't a
>>problem in a PC where the 12V supply can drain 8 A (Not to one slot!!).
>>
>>bye SET.
>>
>Option #3 is not an option...   A voltage doubler like this works on AC, not
DC!
>...
>Robert
 Robert, you don't need AC you only need an square wave, you can generate the
square wave with the PIC and amplify it with a transistor, you can generate the
square wave with 2 transistors or a 555 or a 4093 or any thing that you want.
 I used this trick to handle a MOSFET in a car, for this task I needed at
least 8 V over the battery voltage, I solved this with an output of the PIC at
5KHz driving a transistor with 120mA of Ic (when satured) and 2 electrolitic
capacitor plus 2 diodes, the output is just the double of the battery and drops
4 V if you charge it with 40mA.
 That's all, is cheap but ineficient in terms of transfered energy, but who
cares with a 12 V 8 A power source?

bye SET

********************************************************************************
Salvador Eduardo Tropea (SET) - RemoveMEsalvadorTakeThisOuTspaminti.edu.ar
Work: INTI (National Institute of Industrial Technology) Sector: ICE
(Electronic Control & Instrumentation)
Post (Home): Curapaligue 2124 - Caseros (1678)- Buenos Aires - Argentina

1996\10\10@165138 by William Chops Westfield

face picon face
   Since the supply rail may be up to +15v, the device may be used to
   conveniently switch programming voltage and other such signals.
   Unfortunately, the switching threshhold for "standard" CMOS or 74HC
   parts is VDD/2; if VDD is 12 volts this means the switching thresh-
   hold is at least 6 volts--not something a normal port can deal with.

Um, 6 to 12 volts is well within the range of an "open collector" driver
like the 7407, or have those ceased to exist?

BillW

1996\10\11@040919 by ernhard Schweighofer

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picon face
Bernhard Schweighofer alias spamBeGoneschweigispamBeGonespamsbox.tu-graz.ac.at
(Student at Graz University of Technology, Austria)

On Thu, 10 Oct 1996, Jacob Blichfeldt wrote:

{Quote hidden}

If I remeber right than be aware of the allowed supply voltage of the
74HC(T/U) parts, because the maximum value is just 6V !
(74HC(U): 2 - 6V / 74HCT: 4.5-5.5V + TTL-compatible input levels)

So if you want to switch above 6V (like 12V) use a 40xx part. The
(absolut) maximum ratings for the 40xx are 18V (To be sure, look into a
datasheet because, as far as I know, it differs a little bit from
producer to producer ).

Q'uapla


'In Circuit Programming'
1997\03\11@155227 by ken
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picon face
Can anyone tell me the requirements for programming the C54 in circuit,
what do you need to do with the MCLR pin. I can't find any data in the
microchip data book. I take it that the C54 can be programmed serially
as it can be programmed with the D. Tait type of programmer.

Regards

Ken.

+-----------------------------+----------------------------------+
|   ken hewitt                |   Email TakeThisOuTkenEraseMEspamspam_OUTwelwyn.demon.co.uk   |
+-----------------------------+----------------------------------+

1997\03\11@161120 by Antti Lukats

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face
At 07:42 PM 11/3/97 +0000, you wrote:
>Can anyone tell me the requirements for programming the C54 in circuit,
>what do you need to do with the MCLR pin. I can't find any data in the
>microchip data book. I take it that the C54 can be programmed serially
>as it can be programmed with the D. Tait type of programmer.

nop, you need to use 16C554 if you want to use ICP.
MCLR must have circuitry that allows to be pulled up to +12V,
In programming same applies as for 16C84

Not sure if David's original software supports 16C55X programming
our PIP02 does support, and supports amongst other programmers
David Tait's programmer too

antti

-- Silicon Studio Ltd.
-- http://www.sistudio.com

1997\03\11@195721 by Byron A Jeff

face picon face
>
> Can anyone tell me the requirements for programming the C54 in circuit,
> what do you need to do with the MCLR pin. I can't find any data in the
> microchip data book. I take it that the C54 can be programmed serially
> as it can be programmed with the D. Tait type of programmer.

No, nope, and not a chance.

The C54 has parallel programming only, cannot be programmed byt the D. Tait
type circuit and has no provisions for in circuit programming.

Think about a C55X or C62X type chip. Same footprint but is much closer to
a C84 than a C5X in terms of these issues.

BAJ

1997\03\12@021911 by John Payson

picon face
> Can anyone tell me the requirements for programming the C54 in circuit,
> what do you need to do with the MCLR pin. I can't find any data in the
> microchip data book. I take it that the C54 can be programmed serially
> as it can be programmed with the D. Tait type of programmer.

The 16C54 requires that you control--literally--all of its pins during
programming (well, Vss remains grounded, but...)  One person has posted
on the list that they in fact designed a circuit which would allow ISP'ing
the 54 even under those conditions, but I doubt such a thing would usually
be practical.

To program the '54, you need to power the thing up and take /MClr very
quickly from zero to VPP (about 13 volts I think).  After that each pulse
of the RTCC input will either output the contents of address zero onto
pins RA3-RA0:RB7-RB0 or else try to "burn" the contents of those pins into
address zero.  You should alternate between the read and write until add-
ress zero reads correctly.  After that, you should hit the /OSCin pin to
advance to the next memory location; RTCC will toggle between reading and
writing that.  Continue in this fashion until you have done the entire
chip.

1997\03\12@043519 by Andrew Warren

face
flavicon
face
John Payson <RemoveMEPICLISTspamTakeThisOuTMITVMA.MIT.EDU> wrote:

> The 16C54 requires that you control--literally--all of its pins
> during programming (well, Vss remains grounded, but...)  One person
> has posted on the list that they in fact designed a circuit which
> would allow ISP'ing the 54 even under those conditions,....

   That was me.

> .... but I doubt such a thing would usually be practical.

   You're correct... The method I came up with isn't suited for
   general-purpose programming at all.  If in-circuit programming
   is required, I'd recommend staying away from the 16C5x parts.

   -Andy

=== Andrew Warren - fastfwdEraseMEspam.....ix.netcom.com
=== Fast Forward Engineering - Vista, California
===
=== Custodian of the PICLIST Fund -- For more info, see:
=== www.geocities.com/SiliconValley/2499/fund.html

1997\03\12@045417 by David Tait

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face
Ken Hewitt wrote:

> Can anyone tell me the requirements for programming the C54 in circuit,
> what do you need to do with the MCLR pin. I can't find any data in the
> microchip data book. I take it that the C54 can be programmed serially
> as it can be programmed with the D. Tait type of programmer.

There is a Tait programmer for the C54:

http://www.man.ac.uk/~mbhstdj/upp.html

However it's not intended to program the chip in-circuit as the C54
cannot be programmed in serial mode.  That doesn't mean you couldn't
come up with a circuit to do that (I'm sure Andrew Warren said he once
worked with such a setup) but I doubt if that's the best way forward
nowadays with such a gamut of alternative PICs available.

David

1997\03\12@145334 by ken

flavicon
picon face
I have a copy of P16PRO that was mentioned a while ago, I have check
this out and the circuit that was included in the zip file is a PC
printer port programmer, with only 5 connections to the PIC, Vss, Vdd,
RB6, RB7 and MCLR.

I have run the programming software that was with it and looked at the
device list it includes the 54 and 52, I have not tried it out yet as I
have not got around to building the hardware, should I bother or not.

Ken.

+-----------------------------+----------------------------------+
|   ken hewitt                |   Email EraseMEkenspamwelwyn.demon.co.uk   |
+-----------------------------+----------------------------------+


'In Circuit Programming'
1997\07\25@043320 by Mark Langezaal
flavicon
face
Hello,

I am building a project using the 16C84 and want to be able to use 'in circuit
programming' with pins PB6 and PB7.
Is it still possible then to use PB6 and PB7 as I/O pins?

Thanks,

Mark Langezaal
RemoveMEmlangezaalEraseMEspamEraseMEklm.nl

1997\07\25@055758 by tjaart

flavicon
face
Mark Langezaal wrote:
>
> Hello,
>
> I am building a project using the 16C84 and want to be able to use 'in circuit
>  programming' with pins PB6 and PB7.
> Is it still possible then to use PB6 and PB7 as I/O pins?
>
> Thanks,
>
> Mark Langezaal
> RemoveMEmlangezaalspam_OUTspamKILLspamklm.nl

Yes. Just don't put decoupling caps on them - the programming pulses
are shorted to ground in that case.

--
Friendly Regards

Tjaart van der Walt
RemoveMEtjaartTakeThisOuTspamspamwasp.co.za
________________________________________________________
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'In Circuit Programming'
1998\02\10@102552 by lilel
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face
I've been trying out using in-circuit programming, with no luck.

I built an adapter for my Picstart Plus programmer consisting of a
DIP socket and a clamp-on IC pin probe.  The idea is you clamp it
onto an unprogrammed chip in a board and give it the transfusion.

Great theory.  I only hooked up MCLR/VPP, ground, Vdd, RB6 and RB7.
Are these the only pins that need to be connected?

So far whenever I use the adapter I get "check power and serial
connection"  errors, even when clamped onto a bare chip not in the
board.   Leads are 12" long - is this excessive?

I didn't design a serial programming header into my current project
(D'oh!) and now I'm sorry.  I also have a trace connecting MCLR and
Vdd, instead of the recommended small resistor.  (grrr)  Had to cut
this trace.  Next time I'll design with ISP in mind.


Best Regards,

Lawrence Lile

1998\02\10@140612 by davewave

flavicon
face
I recently finished a design of a CCFD backlight driver using a 16C84 to
control (and store) brightness settings. I cut down the development time
by having the prototype boards made before the PIC code design was even
started. I had the assemblers solder blank PICs on the protos.

While waiting for the protos to arrive, I made an in-circuit programmer
based on David Tait's design. To connect the target PIC to the
programmer, I used a 3M 18-pin SOIC surface mount test clip connected to
the breadboarded programmer with a 3" length of ribbon cable. This setup
works great!

Some things to keep in mind when designing for in-circuit programming:
- Use a small diode  in addition to the usual  resistor between Vdd and
MCLR/VPP
- Carefully examine any circuitry on RB6 & 7 - it must not interfere
with programming
- What happens to other IC's on the board during programming? If
necessary, provide a means of supplying PIC Vdd independantly of the
rest of the circuit. This could be as simple as using a diode.

3M also makes very inexpensive DIP and PLCC test clips. They are
available from Digi Key.

Dave

PS. If anyone is looking for info on CCFD backlight circuits, check out
Linear Technology. Their application notes are excellent.

Lawrence Lile wrote:

{Quote hidden}


'in circuit programming'
1998\07\05@203803 by Frans Gunawan
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face
Does anyone use in circuit programming?
I would like to ask what should be added/changed if I want to use
in-circuit prog.?
How about VDD connection, Microchip's example says, it is connected to
NORMAL connection. But if it is normal connection, it means the programmer
have to supply the current for all chips in the board? do we need jumper
for VDD?

thanks

http://www.poboxes.com/f
f

1998\07\06@024803 by Frank Tamminga

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face
Hello Frans,

> Does anyone use in circuit programming?
Yep, in several projects...

> I would like to ask what should be added/changed if I want to use
> in-circuit prog.?
> How about VDD connection, Microchip's example says, it is connected to
> NORMAL connection. But if it is normal connection, it means the
programmer
> have to supply the current for all chips in the board? do we need jumper
> for VDD?

Microchip has a complete booklet covering this issue. I think Microchip
also has some information on their website.

But, for a quick answer; You can isolate the PIC from the rest of the
circuit using a diode, this also counts for the VPP/MCLR pin. The 13V
programming voltage must be isolated from the rest of the circuit.
At last for the pins RB6 and RB7 (for a PIC16xxx): If possible, don't use
them in your application. If this is impossible, make sure that the circuit
connected to these pins will not interfere the programming.

Success, Frank   (EraseMEp.f.tammingaspamspamspamBeGonehgt.nl)


'In circuit programming'
1999\06\17@133138 by Eric Hufstedler
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Hi Folks,

I am new to the list, and relatively new to PICS.  I poked thru the
archives looking for this answer, but didn't find it. (It may be there,
though: that's a big archive)

I tried what someone else had tried: i wired the picstart into my
circuit to program the pic 12c672.  For me, in circuit means the chip is
in the final application, with no dips, etc to isolate it. I generally
have 10k loads on the pins.

Is there a modification you can make to the picstart (a buffer, etc)
that will allow it to program in circuit?  Is there another relatively
inexpensive programmer that will do this?  The microchip pro-mate costs
$1000, which i will spend if we go into production with this circuit,
but for prototyping, it's a little high.

Thanks for any help,
eric

Eric Hufstedler
Kilovac Division of CIIT
Research & Development
805-684-4575 x152
RemoveMEerichKILLspamspamkilovac.com

1999\06\18@003928 by Ernie Murphy

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I'm currently using the Paralax programmer (Now Tech Tools) for in-circuit
programming. I had in-circuit in mind during the board design Mostly
entailed bringing all the programming pins out to the connector, even
though the 2 extra lines this meant would only be used at 1st test to
insert the code. Also, an op-amp output to a pin was isolated by a 1K
resistor. The only purpose of this resistor is to allow in-circuit
programming.

I did modify the programmer slightly. To keep extra lines on my connector
to a min, I use the + power line to my board (which is designed to run off
18 to 32 volts) I use the switch 5 volt power to turn on a transistor
driver that just supplies the programmers raw dc in to the unit being
programmed.

The unit works well for programming production units. My only beef is for
now I'm stuck using the Tech Tools program for this task... I'd much prefer
to have my own program doing this task (that way I could make the UI geared
to the product I'm building, not a chip that happens to be inside it).

At 09:05 AM 6/17/99 -0700, you wrote:
<snip>
{Quote hidden}

1999\06\18@015605 by Jim Robertson

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At 09:05 17/06/99 -0700, you wrote:

Hi Eric,

The picstart plus is not designed for in system programming but it can
handle it if the conditions are favorable.

I suggest that you add a 1K resistor between MCLR/VPP and ground. This may
make all the difference as the PIC needs to enter the programming mode from
a POR condition. There is no MCLR pull down device, either active or passive,
on the picstart plus.

You will also need to consider the current your target board draws. I do not
know what exactly the picstart plus can source but I would count on much
over 40mA tops. Power is switched  through DG411 quad switches so and not
bipolar transistors that can handle heavier loads. If you have a large
current
requirement on your target you can always power the board via its own PSU and
not bother connecting the VDD signal from the PSP.

If your programming signal lines are isolated via 10k loads then this should
not interfere with ISP however capacitance is another matter. It is not
easy to
buffer the ISP signals as one of them is bidirectional and there is no
direction control available.

I would be trying to first read a programmed chip in circuit then proceed onto
programming.

As far as alternatives go, there are a lot of different programmers available
but relatively few are actually designed for genuine in-system-programming.
One problem with alternative programmers is that the VDD may be sourced only
though an I/O pin of a pic firmware chip. (Eg, Parallax/techtools, DIY-HK
(A.K.A. kits 'r' us) PICALL) This is not always very helpful but you can self
power the target board of course.

Other designs rely on passive pull-up resistors to drive the data signals
and this
again is not helpful to your cause.
(EPIC, P16PRO and other DIY-HK programmers, DT001, PROPIC I&II, and other
TAIT style
derivatives)

For possible workable programmers have a look at.

http://www.propic2.com (Though it is not the propic II you are interested in,
there is a purpose designed ISP programmer on offer linked somewhere to this
page.)

Also see my web site for possible alternatives but really the best option is
a Ver 2 warp-3 but unfortunately these are no longer available. The warp-13
is still a possibility if you lift the ISP signals from the programming
socket. You can drive the warp-13 with MPLAB too so no need to change
software.

BTW. Look carefully on both web sites and see if you can _piece_ together a
_very_ (Very!) low cost production programmer. I have and that is what I
use to
program all my non '5x and 17Cxxx pics. Works absolutely fantastic!


Jim



{Quote hidden}

________________________________________
Email: KILLspamnewfoundspamBeGonespampipeline.com.au
http://www.new-elect.com
WARP-3 SALE now on. $48USD with world delivery.
MPLAB compatible PIC programmers and firmware
upgrades for many programmers.
________________________________________

1999\06\18@020812 by Sean Breheny

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Hi,

I have an EPIC and am currently using it in an in-circuit-programming
configuration for a 16F84. I just placed a resistor (from 2K to 10K)
between any pin that is being used in my circuit and my circuit, and have a
jack ( IDC header) that allows me to plug and unplug the programmer. When
the programmer is hooked up, its pins are connected directly to the
appropriate PIC pins, and isolated from the rest of the circuit by the
resistors. As for power, I simply have a jumper that allows me to switch
the power source from internal power to the power from the programmer. I
also included a jumper which allows me to short the oscillator pins
together to prevent osc. start up. However, I have found that I do not need
to switch either of these two jumpers in this case,as long as the circuit
is powered down. I also do have to admit that RB6 and RB7 are not used in
my app, so no resistor isolation was needed on them,but I don't think there
would be a problem even if they were being used.

Sean

At 04:03 PM 6/18/99 +1000, you wrote:
>Other designs rely on passive pull-up resistors to drive the data signals
>and this
>again is not helpful to your cause.
>(EPIC, P16PRO and other DIY-HK programmers, DT001, PROPIC I&II, and other
>TAIT style
>derivatives)
>

|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
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1999\06\18@081900 by Jack Shidemantle

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The Microchip "ICSP" guide has a sample driver board schematic, but ÊI have
not tried it so can't comment on how well it works. I have used a Needham
Emp20 Êwith a handmade adapter and that worked fine. Am now using the
Promate II with the "ICSP" adapter which cost an extra $300 in addition to
the cost of the programmer. This setup is working very well and I have only
4.7k isolation resistors.

@
Sent by: pic microcontroller discussion list <@spam@PICLIST@spam@spamspam_OUTMITVMA.MIT.EDU>
06/17/99 09:05 AM MST
Please respond to pic microcontroller discussion list

To: spamBeGonePICLISTspamKILLspamMITVMA.MIT.EDU
cc:
bcc:
Subject: In circuit programming


Hi Folks,

I am new to the list, and relatively new to PICS. ÊI poked thru the
archives looking for this answer, but didn't find it. (It may be there,
though: that's a big archive)

I tried what someone else had tried: i wired the picstart into my
circuit to program the pic 12c672. ÊFor me, in circuit means the chip is
in the final application, with no dips, etc to isolate it. I generally
have 10k loads on the pins.

Is there a modification you can make to the picstart (a buffer, etc)
that will allow it to program in circuit? ÊIs there another relatively
inexpensive programmer that will do this? ÊThe microchip pro-mate costs
$1000, which i will spend if we go into production with this circuit,
but for prototyping, it's a little high.

Thanks for any help,
eric

Eric Hufstedler
Kilovac Division of CIIT
Research & Development
805-684-4575 x152
.....erichspam_OUTspamkilovac.com

1999\06\18@091634 by Andy Kunz

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>I'm currently using the Paralax programmer (Now Tech Tools) for in-circuit
>programming. I had in-circuit in mind during the board design Mostly
<snip>
>The unit works well for programming production units. My only beef is for
>now I'm stuck using the Tech Tools program for this task... I'd much prefer
>to have my own program doing this task (that way I could make the UI geared
>to the product I'm building, not a chip that happens to be inside it).

I believe Carmacon has opened up the communication spec to their
programmer.  FWIW, we are using their firmware updates in a modified
Parallax-style programmer (we used their schematic and changed a few
things) for a production bed-of-nails programmer/test fixture.

The neat part about this is that:
       a) we can use Parallax, Carmacon, or Tech-Tools chips in the board, with
the appropriate PC driver
       b) because we can use the open Carmacon RS-232 comm spec, we can burn
chips from the PC, Mac, or Linux box!!!
       c) this also allows us to burn the configuration I2C EEPROM at the same
time.

If you are looking for an OPEN solution, visit their website http://www.carmacon.com

Andy

==================================================================
  Andy Kunz - http://www.montanadesign.com - TakeThisOuTandy.....spamTakeThisOuTmontanadesign.com
          Life is what we do to prepare for Eternity
==================================================================

1999\06\18@170120 by Eric Hufstedler

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> I would be trying to first read a programmed chip in circuit then
proceed
> onto programming.

Yeah, i tried programming once, and when that didn't work, i have been
just trying to verifiy.

I have been probing the signals to look at them, and the difference i
see when i verify with the chip in and out is that the VPP and VDD
signals do have trouble at first because of the capacitor i have on the
output of my 5V regulator.

Someone mentioned the drive ciscuit in MC's ICSP book. I just found that
circuit last night, and will try to build it today or tomorrow. I'll let
you all know if it works.

Thanks everyone for your help!

eric


Eric Hufstedler
Kilovac Division of CIIT
Research & Development
805-684-4575 x152
TakeThisOuTerichKILLspamspamspamkilovac.com

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