Subject:
Re: DIY USB programmer ?
From:
####@####.####
Date:
11 Jan 2005 05:17:39 +0000
Message-Id: <13809.1105420631@www7.gmx.net>
> > Well, those who buy say a bare PCB or a full kit from me, yes, but some
> > people build it all from scratch. They buy the parts from local
> > electroncs stores and mail order places. The people are not just from
> > the US or Germany, but from all kinds of places from all over the world.
> > One guy went to a local place to program the PIC because he couldn't get
> > his DIY JDM to work. AFAIR it costed him a couple of bucks just for
> > programming once...
> >
> > Manuel
>
> Okay, then. How about this. We agree on a design and someone develops
> it--we'll need the software to go with it. Then we give the design to
> Olimex and any other kit/board producing orginization that wants to
> make them. We make the software available to them, as well.
Nice idea.
>
> Now, the only question/decision is to decide if we want to make this
> design to be a 'bootstrap whatever PIC' or 'bootstrap *a* PIC to make
> a *real* programmer for *your* PIC'. The software is a lot easier
> for the latter, but the hardware is a little bit more complex--you
> need a design that is both a bootstrap programmer and a real programmer.
Not really. The design can be very simple, if the right chip is used.
As example the maxim 662 with a silicon diode to increase the 12V to
12.6-12.7V.
The max662 produces 12V up to 30mA using only two caps from 2-6V input
voltage.
The cost is ~2.6 $ for this IC. You can get it as sample.
Tree open collector pins (MCU) using pull-up resistors. The internal one are
to weak.
That is all. Because this is low cost, more rows of socket connectors can be
used
to plugin the IC, like the PIC-PG2C from OLIMEX. So no active routing is
necessary,
as opposed, if a zif socket is used. Ok, manual routing like the EMP
programmer using
pc type switches can always be added as option for for later usage.
The disadvantage from the manual routing using pc type switches is, that the
pbc,
in this case must be double sided. Under pc type switches i mean the
switches used
on a hard drive to set the master/slave mode. Sorry, my english is not the
best.
>
> For my part, I'm willing to make my code for a USB/RS-232 based semi-
> intelligent programmer available. The 18F2550 should be available
> for a few years and we'll see about porting it to whatever successor
> it has when/if it goes away.
The prices are only indicative, and i dont have checked it, use it with
caution.
So, you have a 8$ pic
The PBC will cost between 2$ and 8$.
USB connector 1.5$
max662 2.8$, as alternative, four transistor, tree bigger caps, 4 shotty
diodes,
one ttl or cmos inverter with shmitt trigger,
larger PBC,
so the overall cost is the same.
led+some resistor +caps+
the rest 4-5$ (carrier ic, icsp connector, icsp cable+connector, 6 Mhz
osc).
So , the total cost for a low cost device using the pic usb chip is: 18-25$.
Or 22$ +-20% .
If you want to use psu filters or capacitive 5V stabilizer, 3-4$ adds to the
design.
The cost is not lowered, if a PSU is used, because you need a PSU supply
connector,
a voltage regulator, and tree transistors with corresponding resistors and
caps.
The cable has a cost of 1.5-2$. Because the other usb programmer sold it
separatly,
i don't have included it in the above calculation.
The big problem: USB VID. How do you get one without paying the required
2500$ fee.
Most of the USB programmer design use a FTDI or similar chip with a royality
free
USB VID. Even if there don't do so, if there sold 100 kits, then the usb vid
costs
2$ per item and the VID and the other free PID's are usable for future
products.
You can get a USB FLASH programmer for 35$ (kitrus, sold everywhere),
a ICD2 clone with USB and RS232 for 55 Euro. The above 35$ is a kitrus kit,
a usb
ICSP is sold assembled by kitrus for 39$.
If you add logic to program the USB chip (the programming is a little
problematic
on this chip), using RS232, then the price is or will result to be above of
a equivalent usb programmer kit.
The user must assemble both kits. If Olimex sell this as PBC,
there require to buy a 19$ PBC, update the price, and you see, it's more
convenient
to buy a preprogrammed kit. Otherwiese, there add 10-20%, annother 3-4$.
For 30-60$, there preprogramm a lot of pic chip. If 100 are produced, then
the price
is 0.3-0.6$ X chip. I don't know, if there accept the risk to sell only tree
kits.
You can object and say, the pbc has to be panelized to the other PBC.
True, but then, a FTDI chip is really more convenient to use that can
program the
MCU using the bit-bang mode. It's cheaper for the VID question, the Pbc
space.
Then, if you want, it's possible to design the adapter in such a mode, that
ICSP
trought the bus from the master to the slave cpu is possible.
The kitrus kit costs 26$ in quantity 100 and it has active routing, but only
a voltage triplier, so one need really a 5V USB +-4%. Generally, this is not
a problem.
The last thing. The statement from Manuel was, that for the current and
future design, hi use only 18Fxxx parts and not 16Fxxx. The 18Fxxx parts
don't need necessary to enter the high voltage programming mode in order to
deactivate the
low voltage programming mode. This simplify the thing alot. And otherwise,
there
was always possible to reserve the PGM pin for firmware download and to not
use this
pin for other purposes.
Annother possibility is to use picaxe chips, and if later the basic chip is
not needed anymore, there can be reused. The price is ~2$ above the price of
a pic chip
for the cheaper variants. Connect it to TX/RX (rs232) and program the pic
chip using
the basic chip and maybe a cheap usb2rs232 converter.
>
> I'd like to see a design that will last a few years--maybe until the
> time that USB phases out. :)
>
> Cheers,
> David
>
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