Pic and ICSP

I shoud program a PIC16f877A with a jdm based programmer (PIC-PG2: 
http://www.olimex.com/dev/pic-pg2c.html) and IC-prog. I found a 
schematic for ICSP connection with a jdm-programmer 
(http://www.jdm.homepage.dk/icsp.htm) but i used instead 1n4448 diode a 
1n4148. It doesn't works. Someone can help me?
Thanks
-- 
I have a little dreidel, I made it out of clay
And when it's dry and ready, with dreidel I shall play.
Oh, Dreidel, Dreidel, Dreidel, I made you out of clay
Dreidel, Dreidel, Dreidel, with Dreidel I shall play.

"Sampei" <diego.logrillo@tin.it> wrote in message 
news:ZYnQd.897497$35.33899303@news4.tin.it...
>I shoud program a PIC16f877A with a jdm based programmer (PIC-PG2: 
>http://www.olimex.com/dev/pic-pg2c.html) and IC-prog. I found a schematic 
>for ICSP connection with a jdm-programmer 
>(http://www.jdm.homepage.dk/icsp.htm) but i used instead 1n4448 diode a 
>1n4148. It doesn't works. Someone can help me?

I think the 1N4448 is a typo, I use a 1N4148. It isn't essential, anyway, it 
just protects against reverse power connection, and the target board gets 
its power from the programmer when using ICSP.

I built my own JDM programmer and it seems to have problems when using ICSP 
with certain chips. For instance, I can't program the 16F628 with ICSP, 
although it programs OK using the programmer socket. ICSP works fine with 
the 16F88. Someone else on the Yahoo PIClist has the same problem with it.

Leon 

Sampei wrote:
> I shoud program a PIC16f877A with a jdm based programmer (PIC-PG2:
> http://www.olimex.com/dev/pic-pg2c.html) and IC-prog. I found a
> schematic for ICSP connection with a jdm-programmer
> (http://www.jdm.homepage.dk/icsp.htm) but i used instead 1n4448 diode
a
> 1n4148. It doesn't works. Someone can help me?
> Thanks
> --
> I have a little dreidel, I made it out of clay
> And when it's dry and ready, with dreidel I shall play.
> Oh, Dreidel, Dreidel, Dreidel, I made you out of clay
> Dreidel, Dreidel, Dreidel, with Dreidel I shall play.

I do something similar, 2 diodes (1 in each line), I use 1858 diodes, a
different programmer (it should work the same) and my rb6,rb7 lines
only go to the programmer.

"Sampei" <diego.logrillo@tin.it> wrote in message
news:ZYnQd.897497$35.33899303@news4.tin.it...
> I shoud program a PIC16f877A with a jdm based programmer (PIC-PG2:
> http://www.olimex.com/dev/pic-pg2c.html) and IC-prog. I found a
> schematic for ICSP connection with a jdm-programmer
> (http://www.jdm.homepage.dk/icsp.htm) but i used instead 1n4448 diode
a
> 1n4148. It doesn't works. Someone can help me?
> Thanks

Disconnect your circuit from the power supply completely.  This
programmer depends upon using the negative voltage of an RS232 pin as a
ground.  This is so the positive voltage on another pin will give enough
voltage to bring MCLR to 13V (or so).  If your circuit is connect to an
earth ground (like thru it's power supply), you will not be able to
generate the 13V needed to program the chip.  Depending upon the serial
port used (especially from a laptop) you may not be able to generate 13V
anyway.

This is a typical problem with the CHEAP/CHEESY programmers.

My advice is to get something a bit more "correct".  You will have more
than enough problems to solve without having to worry about your
programmer.  Get a programmer that correctly generates the regulated
voltages needed.