gnupic: Re: [gnupic] About a USB programmer I found
Subject:
Re: [gnupic] About a USB programmer I found
From:
Byron A Jeff ####@####.####
Date:
19 Aug 2006 21:36:01 +0100
Message-Id: <20060819203016.GA29746@cleon.cc.gatech.edu>
On Sat, Aug 19, 2006 at 08:19:50PM +0100, ####@####.#### wrote:
> Hello,
>
> > 1) The 18F4550 requires a Vihh (programming voltage) of Vdd + 4.0V.
> > So if you
> > use my Trivial High Voltage Programmer
> > (http://www.finitesite.com/d3jsys/proghvp.html)then instead of 13V
> > you can use anywhere between 9V and 12V. The easiest voltage
> > source probably would be a 15-16V wall wart and a LM7812 voltage
> > regulator.
> > 2) That schematic doesn't have any cable termination. One of my
> > users discovered
> > that grounding the shield through a small valued capacitor on the
> > target side
> > allows for long cables (longer than 2ft) to work.
> Am. I though I could program it with my laptop's usb current
USB is 5V only. Also you said you didn't have anything other than
USB ports. So any non-USB programmer is off the table.
> > Can you get temporary access to another machine with a parallel
> > port? The good
> > thing about using a bootloader is that programming it is a one time
> > operation.So you don't need to keep a machine with another type of
> > port, just use one
> > long enough to get the bootloader into the PIC.
> Yes I could. My sister went away with it when she married, but I could;
> though I'd need to buy the components, build up the circuit, install the
> software, etc.
> > And you must still resolve the software issue. You asked about
> > another path
> > and I think one exists. Take a look at this page here:
> >
> > http://pic18fusb.online.fr/wiki/wikka.php?wakka=UsbBootload
> >
> > It's a detailed tutorial on building a PICDEM clone with
> > Microchip's USB bootloader.
> >
> > Now there's Linux software to use this bootloader. You can find it
> > here:
> > http://www.internetking.org/fsusb
> >
> Cool, my gcc is a bit older (2.9.5.3), so it didn't compile on a first
> attempt because of nested unnamed structures on bootload.h. But as I'm a
> super-wise linux girl (jeje) managed to do it.
That's good. Now looking at the page with the bootloader, I'm unsure if
there's any way to build the hex file without Windows. But it should be
a big deal for someone to build a hex image and ship it to you.
>
> > Of course you're still stuck in the chicken/egg loop of getting the
> > bootloaderonto the part. My THVP programmer with WinPicProg will do
> > the job, but you need
> > a parallel port to pull it off.
> Ah. I was actually counting (or hoping) that the exe file would be a
> self-extracting zip so i could get the hex file from there.
Nope. You actually have to download everything and compile it. I really find
that odd considering how Microchip usually make stuff available as hex files.
> So, if I build the picdem clone you pointed out --which looks really easy--
> and access somehow to a bootload hex file for the 18f4550, could I do it with
> usb plus the needed power supply you say it needs?
No. As far as I know no standalone USB based PIC programmer exists. I had
started a project to build a trivial bootstrap loader using a USB to serial
converter cable. Used a couple of 555 timers to pull it off. But I never
finished the job. I got caught up in trying to get meaningful information
back from the PIC via the serial port.
The 5V from the USB isn't really critical. You can use a 9V battery to generate
your Vihh/Vpp if necessary. The problem is getting an interface that can be
used to program the part with the bootloader.
> Cool. As you say in your website, some sort of "standard procedure" that
> allows novices to get into this would be really fine, overall for all of us
> which don't know about electronics at all.
We all have to start somewhere.
> Maybe because of usb pics being "relatively new", plus that almost
> everybody within this filed uses windows and parallel or serial ports, that
> there isn't still that much information on the net, or better said not enough
> for someone who knows some linux, but not some electronics (and is as wally
> as me jeje).
The real problem is that unlike the serial or parallel ports, USB is virtually
impossible to manipulate without some intelligence on the client end. So
simply cannot plug something dumb into USB and expect it to work.
BAJ
