It would be wonderful if this experience made its way onto the piclist.com
freeicd page. Hint, hint.

James Newton (PICList Admin #3)
jamesnewton@piclist.com
1-619-652-0593

Steven Allard wrote on 01-5-29 4:47:

Alejandro Lavarello wrote:

> Hi, folks!!!
>
> Well, days ago I have total success making a "do-it-yourself" ICD.  I have
followed the schematics from Patrick Touzet, and it works OK!

I built mine using the schematics in the user guide, (which is on the
Microchip CD rom along with the firmware required) on a piece of veroboard.
After a bit of fiddling it worked well.

> Some things that I have encountered:
>
> 1) Communications: The ICD is formed like a DCE equipment, and needs a
RS232 cable for computer-to-modem (NOT null-modem). I need some
try-and-error  before making a correct cable (this ended vey simple,  a DB9
female to DB9  male straight cable).
> I change the capacitors attached to the MAX232 to 10 microfarads,  and
works OK (100 nanofarads is too small for some kinds of MAX232).

I also changed the caps to 10uf tant. beads

>
> With no computer attached,the LED blinks  at 1Hz. The LED is fixed "on"
when proper communications are established.
>
> 2)Voltages: I have canged the supply 100 microfarads capacitor for a 1000
microfarads
> (the power has drops with 100 micros).

I didn't have this problem which cap. are you referring to ?

>
>  The LED must be a green LED. It needs to have a votage drop of 2V,

My led is red ! However I had to try several from the junk box to find one
which worked.

> because
> is used as voltage reference. One time the communication with ICD was
established,
> one needs to adjust a little R1 and R21 for the correct reading  of the
VDD and VPP voltages.
>  VDD can be measured with a multimeter, then adjust  R1. VPP can be
measured using an oscilloscope; when one touch the button
> "Self Test" in MPLAB, the ICD generates high voltage. The point of measure
is  the union of R21 with R17 and R18 (between 12 to 14 volts).  Anoter
method can be adjust R21 same proportion than R1 (for proper reading  of
VPP).

Initially I had problems getting a high enough Vpp. I found changing Q4
2N2222A for a prop

*************************
This message has been truncated. The entire message is available on your
desktop e-mail client.

--
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