Universal PI Micro

[bugwhiskers]

Most people prefer graphics to numbers or even the position of a needle on a meter. The prototype has 2 vertical bar graphs that are set up to be equal in height when the target is Aluminium or Gold. Silver causes the right hand one to go slightly above the left hand one. Lead causes the left hand one to go slightly above the right hand one and steel even further above. It only takes a few minutes to get used to it and then at a glance you know what the target is likely to be.

regards

bugwhiskers

[BillA]

slick

Cheers, Bill

[johnno]

re:display

Thanks BW for the explination,I had some thought of a horror of trying to decypher a curve similar to an oscilloscope on the fly..
I'll but out and see what eventuates

[wyndham]

BW, a pro board is my vote and BTW try several types of red clay, loose damp, compacted, hard compacted and fired red brick. These may give you a sample database to store in eprom for different ground types if this is where you are taking this. There is also a blue clay that really is red clay but lacks the oxygen to make it red, sort of reduced due to enviorenment.
I might have mentioned thie link before, sorry if redundent. The atom microcontroller might have benifits somewhere along your developement cycle
Chuck Hellebuyck's Electronic Products
I;m looking forward to your next level of developement, Wyndham

[bugwhiskers]

Potential platform

The following link shows a readily available platform with enough I/O ports and other usefull features.
The chip is an ADUC845 from Analog Devices, among other things it has 24 bit AtoD capabilities.

http://www.analog.com/UploadedFiles/..._845_PCB_0.pdf

It comes pre-asssembled with power plug pack cables and programming software for around $75US.

I have 2 on order to test drive but alas they won't be here for 3-4 weeks, Australia is an electronic backwater.

regards
bugwhiskers

[Unregistered]

thanx

maybe this IC max5165 can help us.PLZ look at it.and i am waiting for hex file.plese.
[email protected]

[felix56]

The following link shows a readily available platform with enough I/O ports and other usefull features.
The chip is an ADUC845 from Analog Devices, among other things it has 24 bit AtoD capabilities.

http://www.analog.com/UploadedFiles/..._845_PCB_0.pdf

It comes pre-asssembled with power plug pack cables and programming software for around $75US.

I have 2 on order to test drive but alas they won't be here for 3-4 weeks, Australia is an electronic backwater.

regards
bugwhiskers

Hi, bugwhiskers.
"Potential platform " Is the answer of my help request about hex or asm file for universal PI metal detector.
regards

felix56

[bugwhiskers]

Hi Unregistered,

Thanks for the info. The chip doesn't work exactly the same way as the discrete approach but nevetheless may still be usable and save board space.

In the discrete approach the "IN" pin is an input during sampling and an "OUT" pin when digitising by the AtoD. With the single chip arrangement the buffered and clamped outputs couldn't be used unless de-multiplexed which would require more chips.
Do you know if they also make a matching de-multiplexer ?

regards

bugwhiskers

[bugwhiskers]

MAX5165

I did a search and contacted the local distributor. Farnell NIL, Digikey NIL, local agent NIL plus quoting 19 week lead times and $20US each. Hmffffff !

regards

bugwhiskers

[solmer2]

I wannn one too



Hi bugwhiskers GREAT WORK !!!

I'll buy one so add me to the list.

Good luck.

Solmer2

[bugwhiskers]

Analogue uC overview

The link has a good description of Precision Analogue Microcontrollers.

http://www.elecdesign.com/Files/29/12345/12345.pdf

24 bits equates to 16.8 million or 144 dB......however, many factors influence just how many of those 24 bits can be realised. Because the AtoD will be reading the voltage stored on a cap which is essentially DC I am hoping the resolution will be very high which equates to lots of gain/sensitivity.

One would assume the the evaluation board is very well laid out with noise minimization being the highest priority so the micro looks good. It will certainly be better than any board I or any other amateur could lay out.

regards

bugwhiskers

[rWAVE]

Greetings bugwhiskers,

I have just stumbled upon this forum and your VERY impressive project. CONGRATULATIONS! I am fairly new at metal detecting (Garrett Ace 250), spending most of my time at local, Southern California parks. I now want to head to the beach and search in the wet sand and surf, hence PI. Your project seems ideal.

After reading previous posts, it seems like your design will allow for lots of experimenting with different coil designs. I read with great interest (as I have no experience) "Making a Fast Pulse Induction Mono Coil" by bbsailor; I understand he provided some test coils to assist in your development.

Since your project is uC-based, will it be possible as various coils are built and tested to allow each coil to have a unique "ID" and profile, such that when a particular coil is attached and the PI detector is powered, it can sense which coil is connected and then load the appropriate profile, thus limiting user variables (delays, pulse widths, etc) to only those appropriate for that particular coil?

This would allow those of us outside the project to design and test coils unique to our type of ground and to targets sought. We could then provide coil design parameters (type of coil, diameter, wire size, number of wraps, inductance, resistance, etc) and profile information to the group at large, thereby sharing coils designs? This should allow those of us interested in your project to easily build a family of coils, aimed at specific ground types and targets.

Regards.
Richard

[bugwhiskers]

Hi rWAVE,

Thanks for your interest in the project.
If a 0.1 ohm resistor is inserted in the bottom leg of the "P" channel MOSFET and the top of it is fed to one of the AtoD inputs then a reading could be taken and the pusle width set for that coil based on the time it takes for the voltage to get to 90% of the supply voltage. The micro could be set to do this once on switch on so that virtually any coil could be adapted. There would of course be an over-ride to allow the user to shorten or lengthen the TX pulse to optimise for desired targets and/or conservation of battery power.
The article by bbsailor is an excellent guide to coil making. The coils he sent me work very well indeed and he has been a great help to me with this project supplying a lot of ancillary information.

regards

bugwhiskers

[bugwhiskers]

The following link is I believe the book that comes with the ADUC845 evaluation board. There are some useful tools supplied to evaluate the noise performance of the board.

http://www.analog.com/Analog_Root/st...tartedv1.0.pdf


regards
bugwhiskers

[bugwhiskers]

I dont think my vote will be counting then .. I would be interested in both approaches... a discriminating model .. and the one to work with as am really interested in prospecting model.. would probably work around it and see which one out performs the other ..
Excellent work BW
cheers
gef

Sorry for the late reply to your post gef12.
The evaluation board lends itself perfectly to the original UPIM concept and with the addition a few more components it becomes the discriminating PI so you will get your wish after all.
The 2 boards that have been ordered should be delivered around the end of this month so I can get back to work.

regards
bugwhiskers