gnupic: DIY USB programmer ?
Subject:
Re: DIY USB programmer ?
From:
####@####.####
Date:
5 Jan 2005 20:10:47 +0000
Message-Id: <13325.1104955819@www2.gmx.net>
> On Wed, Jan 05, 2005 at 05:29:31PM +0100, ####@####.#### wrote:
>
[Snippage...]
>
> I don't think speed is an issue. For the project the OP proposed, you'll
> only
> burn once. So it doesn't matter if it takes a minute or two.
>
> My concern is the cost and availablity of the parts to pull it off. FTDI
> parts
> are not cheap, not easily available, and are not easily usable from a
> prototyping/breadboarding perspective. So I tabled them because that's
> zero
> for three.
>
The only big reason that ftdi chips are cheap is there relative low cost
(as off the shelf usb chip) and the fact, that you have the possibility to
got
free usb identifier for a project. Not for the single individual, but for a
company or a hobbistic group / institution. As example if the gnupic
mailinglinst
decide to make a usb pic programmer, then with high probability, there
receive
one or eight free vdi descriptors. With pic MCU's, it's not so easy making a
legal usb device without paying fees for the usb descriptors.
[More snippage.]
>
> I know. that's why I proposed not using the modem control signals at all.
>
> There are no guarantees on how to manipulate the modem control signals.
> There
> are also no guarantees of the latency or the relationship between the
> signals.
The guarantees should be true, but only between rs232 frames. I have tested
this several times on different low cost usb converters (9 - 20 Euro), but
it's certainly
product dependent.
>
> Flat out I don't trust them.
One note to the ftdi chip.
This has a bitbang mode, and this mode requires a dedicated driver
(linux/windows).
Using this driver, a program can program 8 lines as a 8 bit port in a
resolution of
2ms or 1ms, if buffering is used.
The pins are latched every x ms (programmable) and the output/input are
latched always at the same time. It's possible, that the ftdi chip requires
a eeprom in
order to enter in this mode, i don't remember if this works without eeprom.
> [Snippage ]
>
>
> I think you have a skewed vision of the purpose of the project. From my
> reading from the OP this is a single use standalone programmer for a
> flight simulator console. It's not an ICSP programmer for general use.
> It's a one shot one off programmer.
Yes, i have proposed tree other low cost possibility, two of them under 10$
including
worldwide shipping.
> So it doesn't matter how RX and TX are connected. Jumpers and the like are
> not relavent. Neither is the voltage doubler, a 9V battery as you propose
> should be fine for a one off. Reason being is that you can use the one off
> programmer to dump a bootloader into the chip, then you don't need a
> programmer
> anymore.
>
> The goals are to keep it dumb, simple, and cheap with easily available
> parts.
> And nothing is dumber, simpler, cheaper, or more available than a 555
> timer,
> along with a handful of resistors, transistors, caps, and diodes.
But you need a non usb interface.
Theoreof, i can sell a 17/25(zif)$ usb programmer with shipping included,
and a 3$ (+shipping) ICP programmer having 2K user memory expandable with
i2c memory.
There is no real market for this type of gadged (unless you convinced me).
--
+++ Sparen Sie mit GMX DSL +++ http://www.gmx.net/de/go/dsl
AKTION für Wechsler: DSL-Tarife ab 3,99 EUR/Monat + Startguthaben
