Arduino Nano PI Main Discussion

[SaltyDog]

Last minute tuning meant the comments are inaccurate. Sorry about that.
Other than my lax commenting how is the sketch working for you?

So what is the formula? uS to number please. I havn't used the sketch yet, as I want to understand the changes first.
Also, you havn't provided "digitalWriteFast.h" so can't compile .. helps if you distribute "all" the code.

[Gunghouk]

I tuned the software using clock cycles rather than uS in order to give better precision when using the faster integer math equivalents to the floating point maths and used the oscilloscope for fine tuning.

[Qiaozhi]

In the original code the offsets are defined in micro-seconds. All the detector delays and pulse widths are controlled by timer interrupts, but in practice the calculated timer contents do not result in exactly the requested value. This is because there are additional delays introduced by entering and exiting the interrupt routine, and by some internal processing in the routine itself. However, these extra delays are consistent and can be corrected by applying an appropriate offset value.

How to obtain the corrected values is fully explained in the book on page 19.

[Gunghouk]

Last minute tuning meant the comments are inaccurate. Sorry about that.
Other than my lax commenting how is the sketch working for you?

[SaltyDog]

Hi all I'd like to offer my slicked up version of the software sketch for the ANPI detector. I think the changes will go a long way to eliminatiing jitter caused by excessive software times and system noise jitter on the potentiometer.

I'm hoping to try this version out on some lower spec arduino boards to see how they cope.

The pot currently gives about an extra 126 uS on top of the default 10uS. This can be halved to 63uS with a simple mod to the sketch.

Please share your experiences good or bad.

Cheers

[ATTACH]n417564[/ATTACH]

Can you tell me how you got the offset numbers, i.e how does -40 = 8us? Formula please.

// Integer Timing Offset values in instruction cycles ie. ± 6.25E-8 sec intervals (1/16Mhz xtal clock freq)
word TxOnOffset = -40; // TX-on pulse width offset (8us)
word MainDelayOffset = -36; // Main sample pulse delay offset (10us)
word MainSampleOffset = -41; // Main sample pulse width offset (9us)
word EfeDelayOffset = -118; // EFE pulse delay offset (-32us)
word EfeSampleOffset = -42; // EFE pulse width offset (9us)
word TxPeriodOffset = -241; // TX period offset (56us) zz0.d88w9rmuog5zz

These numbers and the comments(us) don't line up i.e 8us=-40. 9us=-41, 10us=-36?

[SaltyDog]

is there a video ?

Will post photos after the hardware is put together, should be finalised this week.

[Qiaozhi]

is there a video ?

Surfdetector made some youtube videos. You can find the link on this page -> Arduino Nano Pulse Induction Metal Detector Project - Published March 2021
BernteOne also made a video here -> https://www.youtube.com/watch?v=Z2XFnPe3u58

[pito]

is there a video ?

[Qiaozhi]

Qiaozhi Hi, I have successfully built the board and have good target distances .... e.g gold ring at 30cm (This is with a mono coil bought off ebay 430uH)

Many thanks for the well designed project. I will be looking at adding further code to the Arduino to implement simple discrimination,
I am thinking along the lines of automatic variation of the delay at various increments, then sample the results to identify pull-tabs/foil etc. Then light a good/bad LED.

Well done.
The Arduino Nano PI is one of my favourite projects because it works extremely well and is simple to construct.
Good luck with the modifications.

[SaltyDog]

Qiaozhi Hi, I have successfully built the board and have good target distances .... e.g gold ring at 30cm (This is with a mono coil bought off ebay 430uH)

Many thanks for the well designed project. I will be looking at adding further code to the Arduino to implement simple discrimination,
I am thinking along the lines of automatic variation of the delay at various increments, then sample the results to identify pull-tabs/foil etc. Then light a good/bad LED.

[SaltyDog]

Hi, yes I realize that, however I don't need the book, I am happy to assemble and test without it ..

[Qiaozhi]

Hi Guys,

Can anyone point me to a complete parts list for the project.

Many Thanks

The Component Parts List is in Appendix A of the book. -> Arduino Nano Pulse Induction Metal Detector Project - Published March 2021

[SaltyDog]

Hi Guys,

Can anyone point me to a complete parts list for the project.

Many Thanks

[Gunghouk]

Hi all I'd like to offer my slicked up version of the software sketch for the ANPI detector. I think the changes will go a long way to eliminatiing jitter caused by excessive software times and system noise jitter on the potentiometer.

I'm hoping to try this version out on some lower spec arduino boards to see how they cope.

The pot currently gives about an extra 126 uS on top of the default 10uS. This can be halved to 63uS with a simple mod to the sketch.

Please share your experiences good or bad.

Cheers

arduino_PI_Fast.zip

[phred01]

has anyone got a spare PCB to sell saving me to have them made plse PM me