Universal PI Micro

[bugwhiskers]

hello how soon is this to be in kit form?
any idea of cost yet?

A lot depends on the number of people interested in it as to whether PCB's are to be made professionally and sold.
As for cost,(all figures are approximates)

Micro $7
LCD screen $15-$150
PCB's $30
Other components $30

regards
bugwhiskers

[johnno]

A lot depends on the number of people interested in it as to whether PCB's are to be made professionally and sold.
As for cost,(all figures are approximates)

Micro $7
LCD screen $15-$150
PCB's $30
Other components $30

regards
bugwhiskers

I would definately be interested in buying one!
johnno

[gef12]

Takers

Hi BW
Ye am sure you will get a few plus takers on this one .. including myself..
cheers 4 now
gef

[johnno]

Hello BW, Considering all the work you have done on your project, are you planning on building this to a workable PI.? I have read earlier posts as this was to "interface for PI's such as Gary's and Hammerhead".
Have I missed something?
Keep up the brilliant work!
johnno

[bugwhiskers]

Hello BW, Considering all the work you have done on your project, are you planning on building this to a workable PI.? I have read earlier posts as this was to "interface for PI's such as Gary's and Hammerhead".
Have I missed something?
johnno

Hi johnno,

I am indeed intent on getting this PI up and running. Initially it was going to be a Universal micro for controlling PI metal detectors then I had the idea of multiple switched capacitors and the potential they had to discriminate. The UPIM is still a motherboard as suggested by bbsailor with all the functions that are common in a PI, ie MOSFET drive, analogue switch drive for integrators, negative voltage generation for OP amps, Screen drive capability, control button read capability and 2 bus sockets for people to put boards of their own designs for experimentation or a re-hash of an existing design like Gary's PI or the Hammerhead.
The UPIM is fulfilling that function for me in that I now have an easy way to test out the switched multiple cap decay sampler.

Early results show that discriminating ironstone is not a problem. The setup I have at the moment that only gets 24 samples (64 or more samples would be better) also shows a distinct difference between a small gold nugget and a steel screw of about the same size.

Over the coming weeks I will be working on finishing off the necessary software to drive the screen and read the buttons and other housekeeping tasks and publishing it here.
It is my fervent hope that any that decide to go down the UPIM path share their discoveries and experiences gained for the benefit of all.

regards
bugwhiskers

[bugwhiskers]

64 SAMPLE BOARDS

The 2 boards that make up the 64 sampler are up and running. The sample caps have been changed from 100nF to 1 nF with an increase in sensitivity not only for signal but also for noise. The major culprit, the voltage doubling charge pump is being modified so it will still produce sufficient voltage when turned off during sampling.
Unfortunately the micro I am using has only enough RAM to store/process 48 of the 64 samples. The preferred micro, ATMEGA644 will be available around the end of April so we will have to wait until then to see the full picture.
The intention at this stage is to get as many samples as possible of the knee of the decay curve with the remaining samples spaced increasingly further apart to the end of even the longest decay. The later samples I suspect will really only indicate the size of the target.
The preferred micro also runs faster (20 MHz) which will allow sampling at 100nS intervals.

regards
bugwhiskers

[Functional]

I've just read through this thread and found it very interesting. I know you mentioned the software you were using, but I'm not familiar with it. Have you heard of the open source program called "Great Cow Basic"? It can be found here:
http://gcbasic.sourceforge.net/about.html

I've done some programming for use in Dos programs and was thinking of learning xBasic, but I have too many demands on my time. I also wondered if you had heard of the software called "PicAxe"? It seems to come with alot of options for projects and tutorials. It's free for personal use and can be found here:
http://www.rev-ed.co.uk/picaxe/

I tried to download PicAxe a couple of years back, but I was and still am on dialup. It's 27 Mb's and kept timing out after about 7 Mb's. Sure looks interesting though. And with all the project options and blank PCB's available, I thought it might be something worth learning, (or at least trying to learn).

Just thought I would mention, that if there are patents, or other legal issues involved relating to intellectual property, having the rights to the application of a finished product, doesn't stop you from allowing others to construct and use it for person use. I've seen some licenses to that effect in the past and its sort of similar in wording, to the software agreement that PicAxe has.

Keep up the good work.

F.

[bugwhiskers]

Hi Functional,

Thanks for your interest in the project.
Atmel, the makers of the AVR micro's have a complete suite of programs and devices that make it very easy to get into it. I use a device called an
AVRISP II, it's about the size of a PC mouse and acts as an interface to your micro for programming. At around $50 including their AVR studio software its a real bargain. There is also a forum site called AVR freaks where all of your answers as a beginner will ne answered very promptly.

I will be posting the source code for the UPIM here. It will have lots of useful routines like driving the LCD display, reading push buttons, controlling the charge pump, switching the MOSFET on and off, etc etc etc. Users will be free to change the code to suit whatever they are trying to achieve and hopefully they will share their knowledge and experiences.

regards

bugwhiskers

[bugwhiskers]

64 SAMPLER SCHEMATICS

The attached .PDF's are the schematics for the 2 boards that make up the UPIM 64 sampler. IC1-IC6 74HC4051. The #2 board has no bus connector, it "piggy backs" on the back of the #1 board and sits very snugly above the micro. This arrangement works but isn't very elegant. Using SMD, all the components will fit very easily on one PCB and the other side of the PCB could be used as a ground plane/shield. Notice AD7 is available and could be used to control the additional chips to make a 128 sampler if deemed beneficial.

regards
bugwhiskers

[Functional]

Hi bugwiskers.

As a non-guru in the field of electronics, I was just wondering if you had considered working with one or more of the PI designers to make a simple plug-in interface, so that anyone who builds your board can easily plug it into they're PI board? Maybe using either a fixed position slot type plug, like an isa card and slot interface, or a cable and plug arrangement like those used for harddrives. Even a USB style connection, with a very short cable, would be possible?

Something cheap and plentiful would obviously be preferred to some proprietary and expensive connection. I don't know if people would want to "hard wire" the two together, as that would leave no option in the event something were to go wrong, or get damaged, short of disassembling and possibly desoldering in order to track down the problem.

Thought I'd throw the idea out there to see what might have been considered already. It just seemed to me that everyone was working on they're own project, without considering that aspect and those who will have to assemble and possibly adapt them to the use of your board, (or visa versa), later on.

Just planning ahead for any eventuality.

F.

[bugwhiskers]

Hi Functional,

Thanks again for your interest in the project.

In my workshop I have about 20 different circuit boards that I have made to test out different types of PI detector experiments over the last yerar or so. Each of these circuit boards has a lot in common ie micro, mosfet driver, charge pump etc etc.

The UPIM motherboard holds all the parts/functions that are common in a PI detector and also 2 bus sockets that allow a user to add things that are different to his/her design.

Importanly there is also provision for a Graphic LCD screen where experimenters without the luxury of a CRO can see things like the shape of the decay curve.

What it allows me to do is change plug in boards without having to re-make the whole thing which is what experimenters really need.

If you fancy the Hammerhead or Gary's PI you are probably better off buying their circuit boards and populating them. However, if you want to experiment with major hardware changes, augmentation and display various parameters then you could hook them up to the UPIM via the bus.


regards

bugwhiskers

[bugwhiskers]

UPIM bus plugs and sockets

The attached pic shows the unpopulated bus sockets. Shown also is the pinhead connector. These type of connectors are the simplest, cheapest and most readily available.

regards

bugwhiskers

[bugwhiskers]

UPIM/64 sampler update.

It's been a while since I posted so it's time for an update.

The preferred micro with 4 times the RAM should be turning up this Friday. This will allow me to show the full 64 samples and on the larger
240 * 128 dot LCD screen too.

About the same time a couple of nice fast sheilded coils that bbsailor has very kindly made for me and posted should arrive.

Tomorrow, a couple of detectorists (not to be confused with terrorists) from the Prospecting Oz forum will be coming to test the 64 sampler with some largish nuggets (hope to get some photo's of that). I am looking forward to seeing discrimination between a block of steel and the nuggets.

Stay tuned.

regards
bugwhiskers

[Ray-NM]

Waiting for Pic's and an update.
RayNM

[bugwhiskers]

Drool time.

The pic shows the UPIM with the 64 sampler boards in place. The kind gents (members of the Prospecting Oz test team) allowed me to test discrimination with the nuggets pictured and I am pleased to announce that there is a distinct difference in the shape of the graph on the LCD screen between any of the nuggets and a block of steel.

The micro's turned up today too so I have a bit of work ahead of me.

regards

bugwhiskers
PS The largest of the nuggets pictured is 17 ounces.