gnupic: DIY USB programmer ?
Subject:
Re: DIY USB programmer ?
From:
Byron A Jeff ####@####.####
Date:
6 Jan 2005 21:44:31 +0000
Message-Id: <20050106214427.GA15639@cleon.cc.gatech.edu>
On Thu, Jan 06, 2005 at 06:32:18PM +0100, Manuel Bessler wrote:
> On Thu, Jan 06, 2005 at 07:19:42AM -0500, Byron A Jeff wrote:
> > > The programmer should have sockets for at least 40/28pin pics and a ICSP
> > > header. Like the olimex PG2C I mentioned before:
> > > http://olimex.com/dev/pic-pg2c.html
> >
> > Bad idea. It's counter to your goal. This should definitely be an ICSP setup
> > where you jumper to the target. It should be ICSP only.
> >
> > Remember it's going to get limited use. So there's no need to set it up as
> > a traditional PIC programmer. Wiring different sockets is tough business.
> > So make it ICSP only and remove that issue.
>
> Thats why I said that I already have that. Olimex has a schematic after
> which I did the layout. And I checked if those pin assignments are
> half-way sane, and I believe they are (maybe not for a production
> programmer, but ok for a prototype programmer).
You missed my point. Your user will still have to solder the sockets. ICSP
keeps it simple.
>
> > No. Keep it simple. A voltage doubler then requires a clock for the pump.
> > It just makes it more complicated.
> >
> > 9V battery and snap, 12V zener, 2 resistors, switch. Simple. Wire the 9V
> > so that the negative is on the 5V line giving 14V on the positive lead. Wire
> > this through the series resistor. Then connect the zener between the other
> > end of the resistor and ground. Wire this junction to one end of the switch
> > and the other to MCLR. Use the second resistor as a pulldown on MCLR. Be
> > sure that the zener resistor is at least 20 times lower value than the
> > pulldown (i.e. 1K for the zener, 20K for the pulldown). Done. When the
> > switch is open MCLR gets 0V. When the switch is closed MCLR gets 12V which
> > is high enough for virtually every flash PIC.
> >
> > Keep it simple. It's a limited time use programmer.
>
> I find that its often easier to use a wall wart power supply than to
> find a 9V battery. just about every computer peripheral comes with a
> power supply. If I need a 9V block battery, I never find one.
>
> So, what about requiring a 9..15V power supply, a 555 charge pump for
> upping the power to 15V, then a 7812 and 7805. That makes sure that
> sufficient power is available.
Better to just require a 12-20V supply and regulate it down.
I see I'm going to have to keep you on point. It's only going to be used
a handful of times. Keep it as simple as possible. A 12V wall wart will work
for any flash PIC. Don't complicate it. 7805 and the 12V zener should be
fine.
>
> Another homecockpit interface solution (not opensource, and
> Win+MS FlightSim only) uses something like that. See here:
> http://fsbus.de/img/FSCOM.GIF
> This solution has the advantage that the PIC burning is built-in.
> The user just has to jumper the to-be-burned board to 'program mode'.
> Of course he has to write the programming algorithms into his flightsim
> interface software. The hexfiles are also compiled into that program.
However his solution uses the modem control signals. I think you may find
failures using a USB to serial cable depending on the USB chipset.
BAJ
