Arduino Nano PI Main Discussion

[MartinB]

Just waiting on a few components to start building. They should arrive tomorrow. Regards, Marty

Hi Marty
I always use this company for my Arduinos Arduino (hobbycomponents.com)
My parts don't arrive until Tuesday because it is Easter

[godigit1]

I finally finished with my Pcb and ordered boards from JlC .
Wow it was super easy. And the price cant be beat in the Us or come anywhere close.
I ordered 5 arduino Pi boards and 5 proto Pro Qs for less than the price of one board locally. And even with two ounce copper.
Yea won't be etching any of my own boards anymore.

Here is the gerber for the Arduino pi pro Q board. any critiquing would be welcome.

arduino Pi Pro Q revA.zip


Some of the forum members have mentioned the pain of routing a 4066 now I know what there talking about especially with the jumpers I added.
This will be a fun project for me having both boards to build at the same time Ill be able to see the exact results of the changes I made for good or bad
Ill post the proto build as I go.
Thanks again for all the help.

[MartyJ1963]

Hi Martin, I have their Website bookmarked because there's loads of good stuff on their site, Handy for the future. Regards, Marty.

[godigit1]

Originally Posted by green
surfdetector has a kit completed on the bench. Maybe he could try to detect a piece of #4 lead shot if #4 shot is a good test target.

I wonder why we can't set a goal and then define what might be required to accomplish the goal. Do we need GEB? Is #4 lead shot a good test target? What distance do we want to detect the test target(GEB on and GEB off)?

If we need GEB, there is going to be a hole. Where would we like it?



#4 lead shot has a diameter of 3.1mm, so from calculation:

[IMG]https://www.geotech1.com/cgi-bin/mimetex.cgi?\tau%20=%20\frac{\mu%20a^2%20\sigma}{\ pi^2}\%20=\%20\frac{(4\pi%20*%2010^{-7})\%20%20*\%20%20(1.55%20*%2010^{-3})^2\%20*\%20(4.55*10^6)}{\pi^2}\%20=\%201.39\mu% 20s[/IMG]

in this case the current implementation of the Arduino Nano detector should not be able to detect #4 lead shot. This is because the minimum main sample delay is 10us. Since 5 * 1.39us = 6.95us, the eddy currents will have died away long before the main sample occurs. The 10us minimum delay is caused by the software overhead due to setting up the timer register and entering and exiting the interrupt routine. However it should be possible to get below 10us if the delay is produced without relying on the timer. Of course this would still require a suitable coil, and possibly a reduction in the TX pulse width.

The actual position of the target hole will depend somewhat on the soil conditions, and consequently the TC you're trying to ignore.

Is #4 lead shot a realistic target to use for testing?
Carl has previously said: "If you can detect a #9 lead shot, then you can detect most 1/2 grain nuggets".
Calculating the tau of #9 lead shot gives 579ns. Which means that the eddy currents have vanished after only 2.9us.

Hi Qiaozhi,

From this post in extra extra Deep detector thread Min 1st sample delay is currently set to 10 us due to the interrupt routines.

I'm still in my infancy of trying to functionally understand code but I found this tread on the arduino forum that mentions using the Millis command instead of the delay command to seemingly perform two functions at once.


This is the thread.
https://forum.arduino.cc/index.php?topic=503368.0

Not knowing all the pitfalls of programming and trying to learn still.
I wanted to ask (before I went down a long wrong road ) if you thought this was a viable method of possibly speeding the code?


My first goal would to be able to get the Arduino Pi code first sample spacing to 5 us or at least 7 or 8 would be a good #.
This would make the mods made to Pro Q front end even worth while and from there I can start working in the Gb to the code Or maybe Ill have to bribe somebody.

As far as booting from a Sd Card in the field, Ive found three ways to do that but need to pull the trigger on what Sd card or data logger I want to try.

I was glad to see green and you all talking about a arduino based gold detector as that wasn't really my intention here.
I was just wanting more of a learning platform mainly for the coding end with a simple GB.

Would love to see a arduino conversion of something like the GS 4 That would be fun..

Thanks Again

[godigit1]

Going back to the Nannos That dont work.

I ordered three elegoos and they booted right up One avr dude did not.
The fix was to load the old bootloader under tools, Processor .

This may not be the solution for all the boards but at least worth a try.

[Qiaozhi]

I'm still in my infancy of trying to functionally understand code but I found this tread on the arduino forum that mentions using the Millis command instead of the delay command to seemingly perform two functions at once.

This is the thread.
https://forum.arduino.cc/index.php?topic=503368.0

Not knowing all the pitfalls of programming and trying to learn still.
I wanted to ask (before I went down a long wrong road ) if you thought this was a viable method of possibly speeding the code?

There would probably be even more delay introduced by using the millis() function.

If I wanted to create a shorter main sample delay, I would combine state 1 and 2 of the interrupt state machine and create the delay by invoking the NOP command a few times via an assembler call.
For example: "__asm__ __volatile__ ("nop\n\t");".

I think that this single instruction will introduce a delay of 62.5ns, but I would have to test it to be certain. Try adding a for loop around the asm call in your sketch and measure the delay on the scope.

[green]

Originally Posted by green


I wonder why we can't set a goal and then define what might be required to accomplish the goal. Do we need GEB? Is #4 lead shot a good test target? What distance do we want to detect the test target(GEB on and GEB off)?

If we need GEB, there is going to be a hole. Where would we like it?




Thanks Again

What I'm doing today, maybe different tomorrow.
Tx time, 160us
Tx rate, 1000pps unipolar, 2000pps bipolar
target delay time, adjustable front panel(3.5us to 20us)
target sample time, adjustable front panel(5us to 20us)also used to adjust GB, needs fine adjust
GEB, front panel on-off
ground delay time, 4us haven't played much with different times
ground sample time, 100us
Open to suggestions to make it better. Never learned micro's so can't help with programing. Still need to define control loop whether it's done with logic or micro.

unipolar needs an EF sample also

[6666]

One problem we all face around the world when out in the field detecting is mains electricity interference which is either 50 or 60 Hz,
if we make the PI Tx rate 1200 pps this number is divisible by both 50/60 Hz .

By both using 1200 pps and having the ability to change the Tx rate + or - slightly in code can help tune out and reduce the mains interference .
It usually manifests in a PI detector as a "beat" frequency in the receive audio by giving a constant rise and fall in detector threshold audio
the surf pi is prone to it in a 50 Hz country.
Just something to consider when writing code.

[bernte_one]

Hi Carl,

can you place the complete partlist here as pdf or txt document, would be nice to have this extra

i dont want to add the hooks on the book pages after installing components (yes i do checklist for each detector while assembling)

[gbrowne]

Thanks for the background, sounds like par for the course eh I've just orderd a Pi zero and a fast AD board. I'll capture some curves from various targets, ground conditions etc and see what can be gleaned. If a Pi-Pico at 133Mhz can sample at up to 500k samples/sec and also fo FFT in real-time, who knows what maths magic can happen with a 1Ghz clocked Zero ? MInd you, my coding's ok, but my maths is pants! Probably just load it all into calc and see what it looks like first. G.

[6666]

Got to wait a few weeks for mailing from USA, but fingers x'd.

The Amazon nano's arrived, tried one, it works with the IDE, more later.

[green]

One problem we all face around the world when out in the field detecting is mains electricity interference which is either 50 or 60 Hz,
if we make the PI Tx rate 1200 pps this number is divisible by both 50/60 Hz .

By both using 1200 pps and having the ability to change the Tx rate + or - slightly in code can help tune out and reduce the mains interference .
It usually manifests in a PI detector as a "beat" frequency in the receive audio by giving a constant rise and fall in detector threshold audio
the surf pi is prone to it in a 50 Hz country.
Just something to consider when writing code.

I'm guessing the problem is aliasing on a harmonic of the mains. An exact 1200 Hz should work. 1201 Hz sample should give a 1 Hz signal, maybe worse than sampling at 1000 Hz. What am I missing? I haven't seen the "beat" frequency. Any suggestions what I might try to cause it?

[waltr]

I'm guessing the problem is aliasing on a harmonic of the mains. An exact 1200 Hz should work. 1201 Hz sample should give a 1 Hz signal, maybe worse than sampling at 1000 Hz. What am I missing? I haven't seen the "beat" frequency. Any suggestions what I might try to cause it?

I have seen (heard) this when trying to detect near some high Voltage transmission lines also a few times in my basement lab when the heating system's pump runs.

To cause it put a AC mains device near the coil. Something inductive.

My HH2 runs at 1600Hz and has a fine frequency adjustment pot the 'null' the AC mains beat. Pot into ADC on PIC processor which adds/subtracts a small delay on the cycle timer. Due to the PIC running its internal RC clock the Frequency drifts with temperature enough that in my lab verse the field the cycle time changes. A XTAL would be better but will still have a temperature frequency change. So slight adjustment may be needed in the field (like on the TDI detector).

[Qiaozhi]

My HH2 runs at 1600Hz and has a fine frequency adjustment pot the 'null' the AC mains beat. Pot into ADC on PIC processor which adds/subtracts a small delay on the cycle timer.

You can easily add an external pot to the Arduino Nano PI to allow adjustment of the TX repetition rate, in the same way as the Delay pot is implemented.

[surfdetector]

The Amazon nano's arrived, tried one, it works with the IDE, more later.

Good to hear. Glad that they are working for you.