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Programming the pic16F84A

L

lerameur

Jan 1, 1970
0
Hello,

I have been trying to build a programmer for the PIC16F84A microchip.
After a couple of design not working. Then I found this web site
(http://sciencezero.4hv.org/electronics/com84.htm) stating that a 13v
produced by the serial port is needed. From my voltMeter, I can only
record about 0.5v.
They say that newer computer do not have enough voltage at the serial
port.
Is this true ? If so How can I fix the problem.
I tested 4 circuits over and over again, they cant be all wrong..

ken
 
H

Homer J Simpson

Jan 1, 1970
0
They say that newer computer do not have enough voltage at the serial
port.
Is this true?

I doubt it's true, but I'd suggest a kit, from eBay perhaps.
 
J

Jon Slaughter

Jan 1, 1970
0
lerameur said:
Hello,

I have been trying to build a programmer for the PIC16F84A microchip.
After a couple of design not working. Then I found this web site
(http://sciencezero.4hv.org/electronics/com84.htm) stating that a 13v
produced by the serial port is needed. From my voltMeter, I can only
record about 0.5v.
They say that newer computer do not have enough voltage at the serial
port.
Is this true ? If so How can I fix the problem.
I tested 4 circuits over and over again, they cant be all wrong..

You really should use an external power source. You can use a cheap DC
adaptor with a regulator. You will need both 13 and 5V's so you'll probably
want something like a 15-17V DC adaptor with a 13V and 5V regulator. Once
you got this you'll also need a tristate ic so you can control them and a
few transistors to interface the power with the pc. There are plenty of
schematics out there for it. The one your looking at is pretty basic and is
crap.

http://www.bobblick.com/techref/projects/picprog/f84pgmsc.gif

something like this should work... its very similar to what I did and I
didn't have a huge problem with it. (although I used a bench supply so I
didn't need the regulators). If your not using Winpic then you should pic
that up as its probably the best to use. It also has many default settings
for popular programmers. You gotta make sure that the controls from the pc
match what the pic see's. i.e., when the software turns on the main voltage
it actually comes on and doesn't go off or something like that... also that.

in win pic it lets you test the controls to so you can figure it all out
quite easily.

Theres tons of resources on the net and spending a little time with google
might make it much easier.

Jon
 
L

lerameur

Jan 1, 1970
0
Jon Slaughter a écrit :
You really should use an external power source. You can use a cheap DC
adaptor with a regulator. You will need both 13 and 5V's so you'll probably
want something like a 15-17V DC adaptor with a 13V and 5V regulator. Once
you got this you'll also need a tristate ic so you can control them and a
few transistors to interface the power with the pc. There are plenty of
schematics out there for it. The one your looking at is pretty basic and is
crap.

http://www.bobblick.com/techref/projects/picprog/f84pgmsc.gif

something like this should work... its very similar to what I did and I
didn't have a huge problem with it. (although I used a bench supply so I
didn't need the regulators). If your not using Winpic then you should pic
that up as its probably the best to use. It also has many default settings
for popular programmers. You gotta make sure that the controls from the pc
match what the pic see's. i.e., when the software turns on the main voltage
it actually comes on and doesn't go off or something like that... also that.

in win pic it lets you test the controls to so you can figure it all out
quite easily.

Theres tons of resources on the net and spending a little time with google
might make it much easier.

I finally got that crappy circuit to work with the power supply at 5
volt.
Eventually I would like to program bigger chip, I was inititially
thinking of doing this circuit:
http://feng3.cool.ne.jp/pgm5v2/sch528.gif
They use a ZIF socket to accomodate chips up to 40 pin.
But this circuit do not have a power supply.
I am gussing it did work for Feng...

ken
 
J

Jon Slaughter

Jan 1, 1970
0
Jon Slaughter a écrit :
You really should use an external power source. You can use a cheap DC
adaptor with a regulator. You will need both 13 and 5V's so you'll
probably
want something like a 15-17V DC adaptor with a 13V and 5V regulator. Once
you got this you'll also need a tristate ic so you can control them and a
few transistors to interface the power with the pc. There are plenty of
schematics out there for it. The one your looking at is pretty basic and
is
crap.

http://www.bobblick.com/techref/projects/picprog/f84pgmsc.gif

something like this should work... its very similar to what I did and I
didn't have a huge problem with it. (although I used a bench supply so I
didn't need the regulators). If your not using Winpic then you should pic
that up as its probably the best to use. It also has many default
settings
for popular programmers. You gotta make sure that the controls from the pc
match what the pic see's. i.e., when the software turns on the main
voltage
it actually comes on and doesn't go off or something like that... also
that.

in win pic it lets you test the controls to so you can figure it all out
quite easily.

Theres tons of resources on the net and spending a little time with google
might make it much easier.

I finally got that crappy circuit to work with the power supply at 5
volt.
Eventually I would like to program bigger chip, I was inititially
thinking of doing this circuit:
http://feng3.cool.ne.jp/pgm5v2/sch528.gif
They use a ZIF socket to accomodate chips up to 40 pin.
But this circuit do not have a power supply.
I am gussing it did work for Feng...


Yeah, but its still better to use an external power supply since the
standard for the pc ports is not all that standard. It may or may not work
in some situations. Its very easy to use an external power supply so one
might as well do it if they want the programmer to be more robust.
 
P

petrus bitbyter

Jan 1, 1970
0
lerameur said:
Hello,

I have been trying to build a programmer for the PIC16F84A microchip.
After a couple of design not working. Then I found this web site
(http://sciencezero.4hv.org/electronics/com84.htm) stating that a 13v
produced by the serial port is needed. From my voltMeter, I can only
record about 0.5v.
They say that newer computer do not have enough voltage at the serial
port.
Is this true ? If so How can I fix the problem.
I tested 4 circuits over and over again, they cant be all wrong..

ken

Ken,

That COM-port powered programmers tend to work well when 1488 drivers are
used in the PC. The output voltages of that drivers are close to +/-12V when
powered by appropriate power supplies. These days the drivers are often
build in a larger IC and have lower output voltages although well within the
RS232 specs. Especially notebooks may use MAX232-like solutions that do
about +/-9V. Good enough for serial communications but too low for
programming PICs.

So to stay on the safe side you'd use an external power supply. Examples:
http://www.oshonsoft.com/picprojects.html
I build the parallel port programmer myself:
http://www.oshonsoft.com/picprog.html

Another programmer can be found:
http://www.voti.nl/wisp628/n_index.html
Also available as a kit.

Which are only two examples among many, many others.

petrus bitbyter
 
T

techie_alison

Jan 1, 1970
0
lerameur said:
Hello,

I have been trying to build a programmer for the PIC16F84A microchip.

Hello :)

Definitely buy one off of eBay. It removes uncertainly from the equation
(most of the time..) Try to go for a PicStart+ or ICD2 clone rather than
one of these 'kits'. It was the best thing I ever did and I'd used a DIY
programmer for about a year.

The 16f628 would perhaps be better to start with too.
 
B

Byron A Jeff

Jan 1, 1970
0
Hello,

I have been trying to build a programmer for the PIC16F84A microchip.

Before you proceed too far with the 16F84A take a read of my PIC
16F88 comparison page:

http://www.finitesite.com/d3jsys/16F88.html

while getting started with a 16F84A is probably OK, you'll probably
find that you'll quickly run into some real limitation before too
long.
After a couple of design not working.

Which designs are those.
Then I found this web site
(http://sciencezero.4hv.org/electronics/com84.htm) stating that a 13v
produced by the serial port is needed. From my voltMeter, I can only
record about 0.5v.

That's not good at all. Most serial ports generate at least 0-5V.
They say that newer computer do not have enough voltage at the serial
port.
Is this true ?
True.

If so How can I fix the problem.

Answer #1: Don't use the serial port.

Answer #2: supplement the voltage.

But serial ports are a crap shoot. Parallel ports tend to have more
stable specifications. Take a look at my Trivial High Voltage Programmer

http://www.finitesite.com/d3jsys/proghvp.html

as a sample. Note that it requires an external 13V power supply.

With newer chips such as the 16F88 you can also program with low voltage
which obviates the need of a high voltage supply. Also many newper parts
only requires a Vpp of +3.5V above Vdd. So often you can program using
a 9V battery as the high voltage source.
I tested 4 circuits over and over again, they cant be all wrong..

They could be. What are they? Also what software are you using?

BAJ
 
L

lerameur

Jan 1, 1970
0
yes actually I just saw that the PIC16F88 was a much better choice then
the 16F84A I'm going to look in to ebay if my circuit do not work. But
for now I want to try to build my own. I just order a plain board (15$)
and I will install myself the component, that should be wiser then
etching the board myself. I have a pic progammer from microchip I can
use to compare that from school so I,ll see if its the board or me (or
the program ) my problem.
Also one more thing.

On the web site they say to use a 13-18V 150mA transformer adapter.
I called the electronic stores nearby and they only have a minimum of
600mA. Would that work also?? . they guy at the store told me it would
and I wont burn up the circuitry.
Here is the board page:
http://www.embedinc.com/easyprog/index.htm


ken


techie_alison a écrit :
 
H

Homer J Simpson

Jan 1, 1970
0
On the web site they say to use a 13-18V 150mA transformer adapter.
I called the electronic stores nearby and they only have a minimum of
600mA. Would that work also??

Sure. A power outlet can deliver 2500 watts. You can plug a 15 W lamp in OK.
Same principle.
 
L

lerameur

Jan 1, 1970
0
Homer J Simpson a écrit :
I called the electronic stores nearby and they only have a minimum of
600mA. Would that work also??

Sure. A power outlet can deliver 2500 watts. You can plug a 15 W lamp in OK.
Same principle.

oK THEN

I just thought that the circuit was design to support 150mA. By putting
600mA I thought it would be too much and things would start to melt..

ken
 
H

Homer J Simpson

Jan 1, 1970
0
I just thought that the circuit was design to support 150mA. By putting
600mA I thought it would be too much and things would start to melt..

Nope. Excess voltage kills things.
 
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