SpiMX Shield (uses Arduino)

[Tec]

I have been working on PI again..

Building a new version of the SpiMX , the 'Spi MX Shield', the improvements are:

1.
Using an Arduino Leonardo as the micro controller:
Ready to go, can plug it on , don't have to worry about assembling a micro controller.
The code is tidier (written in c, not arduino language), the previous pic code was messy.
I think arduinos are great hardware platforms.

2.
Completely different sampling/analog part. It is more like other PI designs;
The coil signal is amplified, gated (sampled) and then measured with an AtoD.

3.
Automatic sampling gate.
Sampling is triggered by the coil discharge. It is always synced to the 'knee' of the curve.

4. Simpler and better switching of Mosfets.

It still shares features with the old design:
Bi-polar pulsing
Conductivity calculation.


I have only tested the prototype, it seems quieter and deeper, am going to assemble a PCB soon.

[joop]

Hope to see some of the code soon. I have also been experimenting with arduino in a PI detector. Do you use a separate ADC?

[Tec]

Hi,

No I am using the built in 10 bit ADC, fairly low resolution, but it is quite fast.
The Leonardo has built in 2.5V reference..

The signal has been amplified , averaged , and amplified again by the time it gets there..
as a ripply DC signal.
The ripples are the pulses, and the sampling is synchronized to the pulses, so this noise is removed..

Tec

[Taktyk]

What is your current transmitter in your project?

T.

[Tec]

Schematics SpiMX Shield rev b

Here is the schematic rev-b (will be minor changes)

It should be clear enough to understand and duplicate, for anyone who wishes to do so (but don't tell anyone )

I have started testing, I'm happy with the performance so far. very quiet.

FIRMWARE:

I will post that soon.
It is written in C using Atmel Studio-6, and it is a masterpiece (even if I say so myself).

[Tec]

SPI-MX Shield Software. For Arduino Leonardo. Atmel Studio 6

SPI-MX Shield Software. For Arduino Leonardo. Atmel Studio 6

[6666]

Thanks.

[joop]

Thanks for the code.... Oh boy, atmel studio 6... Wonder if it is portable to other Platforms, I am using Linux with the Arduino IDE. I guess if it is written in C I might be able to use the code.

[joop]

I have spent one evening porting your code to the ARDUINO IDE. Seems to compile without errors. I can't test it on the hardware yet, I am waiting for my Leonardo Board to arrive from China ;-). Also, haven't looked at the schematics yet...

Are you interested in the ino file? It only took a couple of changes to work, which I can explain in detail later...

[Tec]

Re sketch files

Hi Joop,

I am definitely interested in the sketch files, I can test it here.
I am getting a few more PCB's this week , after they are assembled and tested I could send you one.

Attached is the most recent schematic. Replaces the old one.

Tec

[Tec]

Latest schematic rev C

I don't know how to remove old uploaded files. This replaces the old version.

[CAS]

Looks like a very interesting project. Thanks for posting your info.

I have been playing with a MicroChip Uno32 and looking at creating a shield to work with that.

What sort of performance have you gotten so far? ie depth on small objects, issues with mineralised soils etc.

[joop]

I am definitely interested in the sketch files, I can test it here.

Here it is: SPI_MX_3b.txt. Rename the file to extension .ino before loading it into the arduino IDE.
All of the code is in one file.... there were only 3 minor changes: PD5 was replaced by PORTD5, GlobalInterruptEnable() by sei() and GlobalInterruptDisable() by cli(). I left out all of the unused code, like loading the config from eeprom. Hope that's okay for now, it made the code easier to read for me.

I had a quick look at the schematics. Some parts don't have values, like IC1, U6, U8, U10, U11, and U17 in the analog signal diagram also U16 in the supply and micro diagram.

Yes, a PCB would be nice and I am willing to pay for it. I think this is a nice effort!

[CAS]

I would be interested in a pcb too. What sort of $ would you be looking for?

[Tec]

Schematics

Added some missing part numbers.