On Mon, 5 Jan 2004 18:49:47 -0500, Olin Lathrop wrote on Re:
[PIC:] Pic as an i2c slave:

>> The waste of time you are mentionning has been mine for days
>> and weeks now

>If this is a commercial project, then it sounds like a proper solution =
has
>some real worth. =20

There is nothing confidential in what I am doing, so here
goes: it is a project that I delopped in an
amateur/professionnal astronomer association (600 members in
the world and counting) called Aude
(www.astrosurf.com/aude).=20

We build and use CCD cameras for astronomy; in fact we
invented them, or rather one of our amateur members called
Christian Buil (www.astrosurf.com/buil) did eons before
professionnal astronomers even considered using them; he
wrote a book on this (http://www.willbell.com/ccd/ccd4.htm).

Given that the license for building those cameras was free,
our work have given birth to a *for-profit* US firm and
camera system called Genesis, which is basically a clone of
our Audine camera.

It is well known that a ccd camera is more useful when the
sensor's temperature is regulated; also amateur astronomers
are famous for blindly wandering at night in the
countryside, far from any source of energy; so, starting in
1999, I built a range of battery-fed, switching power
supplies that provide, from a single 12VDC source, all
tensions that are necessary for the camera, including a
regulating voltage source for a Peltier module; I have
programmed a PID regulator in a 18F876, using a DS1820
Dallas Semiconductors Onewire sensor that allows better that
0.1 K regulation. From a fully charged battery, one can
image for a full three nights without recharging. Which is
what people needed.

We have also explored the future of CCDing by building an
Ethernet to parallel converter
(http://www.astrosurf.com/ethernaude/) that allows one to
image from a remote location: no PC is required at the
telescope, only a battery and my power supply
(http://www.mecastronic.com/AlAudine_NT.htm) containing an
Ethernaude interface.=20

As an example, I have in september installed such a
configuration on a telescope that is managed by us on top of
Pic du Midi (www.bdl.fr/s2p) in the french Pyrenees
mountains, and requested a friend in Paris to image from his
home through the internet, using the UDP protocol.=20

A US commercial builder, Santa Barbara Group
(http://www.sbig.com/), sells an equivalent, though less
efficient I/F (http://www.sbig.com/sbwhtmls/ethernet.htm).=20

Our I/F is available for a slight amount above the price of
construction (see mecastronic link above).

Now why do I need i2c? The Ethernaude I/F uses an SX
microcontroller and has an i2c bus that seems to work (it
works with standard slaves such as PCF8574, and I have
checked that my i2c problems happen either with this I/F or
with a // port I/F I have built, which seems to rule out a
problem on the I/F side).=20

We need to control my power supply from the Ethernaude I/F
through the I2C bus, knowing that Ethernaude is an i2c
master and this cannot be modified. Also we need to use a
pic, programmed as a slave, as an i2C to RS232 symmetrical
interface that will allow us to remotely control the
telescope through its RS232 own interface.

The fact that for any reason and after much debugging, I
have been so far unable to ***reliably*** operate (basically
it works, it is just not reliable and I do not know why) a
PIC as an i2c slave precludes such goals.

Please note that all of those activities (there are others,
such as managing said telescope (www.astrosurf.com/t60), one
of my responsabilities), are strictly performed in a non for
profit context, because our association does not have any
R&D budget (which means that each and every "researcher"
among us pays good euros from his pocket for prototypes
etc).

>I and several others here could probably give you a fixed
>price for a complete solution given a proper specification and =
verification
>procedure.

I suppose so, and it certainly looks as if you could. There
are also such solutions available around us; none of them we
can afford.=20

>> This is why I am seeking here a higher and hopefully
>> friendlier level of help, in the form of working, true and
>> tested example code.
>>
>> No less.
>
>Oh, I see.  You've got a problem which you've wasted days and weeks on, =
but
>are demanding a free solution for? =20

Correct. I do not see why anyone should be shocked by such a
request; I have monitored Melabs PicBasic Pro mailing list
for months now, it is full of professionnals that provide
free help to beginners and confirmed people alike, and go to
great extents to this end, including spending time to
actually "prototype" and solve other's problems.=20

Names that come to mind (this list is not exhaustive by far)
are Melanie Newman, Timothy Box, Darrel Taylor, Bruce
Rentron, Dennis Saputelli, modestly myself, some of them are
present on this list also...=20

I may have been spoiled, but this is the kind of behaviour I
am prepared to find on this list also. And I can't suppose
people are on this list chasing customers...

>How much were those days and weeks worth? =20

They were lost to me; if I had not stumbled, maybe for the
first time in my "enlightened amateur" life <grin>, on
something I cannot solve, I would have put them to better
use in some other projects I (we) have in mind, that require
my competences, such as e.g.:

- GPS-based or otherwise-based datation system for astero=EFd
occultations, precise to better that 0.01 second WRT GMT
time (this is a crucial need for amateur and professionnals
alike, nothing available on the market at realistic prices,
which excludes IRIG-B type clocks and such)

- Precision focusing system for telescope with CCD cameras
(there are some on the market that need be improved) .

- 3-axis Motion Control card for "GOTO" telescope control.

- etc.

>How much is it worth to have everything just work? =20

Do you live in a world where everything has a commercial
price? Or, as others on the internet do, do you have a
secret "not for profit" garden?

>Is the answer to that really $0?

The answer here is a qualified "Yes". After all Socrates did
not have a commercial stand on the agora...

Thanks for your time reading this.

* Xrobert.soubie@free.frX (veuillez supprimer les "X")
* http://www.astrosurf.com/soubie
* Au royaume des aveugles, les borgnes sont mal vus... - P.Dac

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