Android Phone Based Metal Detector - FCMD

[moodz]

Which AI do you use Moodz?

https://claude.ai for most and Grok for low level cpu.

[Repwoc]

Which AI do you use Moodz?

[moodz]

LOL - gas warfare is banned by the Geneva convention.

Added bode plotting ( AKA frequency response ). Here we are sweeping a short piece of wire connecting the dac to the adc input.

For those who are following the plot ... all these functions are being added to the STM32 chip so the phone only has to do the nice display ( no DSP load ) wink wink.

big question is : Why would we want a bode plotter in a metal detector ?

[ivconic]

Sometimes you just don't want too advanced technology arround you:

https://youtube.com/shorts/mgp5FxAYho0?si=OgF9oQO1UkiVuic_

[moodz]

That seems like the ideal micro for a metal detector. Considering a 16bit 250ksps adc in small quantities are about $20 usd each.
Thanks

ADC prices are outrageous when you need one.

This one ( there are 3 x 16 bit ADCs on the H750 ) is not too bad for an integrated converter. The package type for the CPU can have some impact on noise as well.
AT 2.5 msps ( fast enough to sample a PI ). you get about 13 - 14 bits ENOB and that can be made better with oversampling and averaging.
Internally the oversampling is done in hardware ( upto 1024x ) so zero CPU utilisation cost. I use 16 so I can have 200KSPS which gives me a nyquist cutoff of 100Khz maximum transmit.
The only downside I have found is that the flash size is 128K ... which isnt ideal if you include a few bloatware libraries in your code.
The board is a a Weact Studio

I buy them for $10 - $20 AU from Alibaba. You cant see it below but there are two external QSPI External Flash memory chips mounted to compensate for the limited onboard flash.
They also support Boot0 so you program them without an stlink programmer.

[Altra]

That seems like the ideal micro for a metal detector. Considering a 16bit 250ksps adc in small quantities are about $20 usd each.
Thanks

[moodz]

The internal "16 bit" ADC1 ...oversampled 16x for 200ksps. Total time to build the Python app and the STM32 C code was about 2 hours of me telling AI what to do. Some jobs are definitely going to go .. but people with ideas but don't know how to code will be winners in the near future. As long as AI never wants to drink beer we'll be OK.

[Altra]

Looking good! Are you using the internal adc or external?

I'm glad I have retired. I watched a youtube video today and they were saying within in two or three years, millions of jobs will be eliminated due to AI. This will cause social disorder and a revolt against big tech.

[moodz]

with the help of my AI mate ... I have built a syncronous detector in the STM32H750. A python GUI talks to the chip via the inbuilt USB port. Below is the initial code extracting a transmit signal from the noise with RX amplitude and phase plotted over time.
Not bad for a $5 chip.

[moodz]

FCMD code ported ... full demod and phase slope implemented in code. Its just the stm32h750 chip .. no coils connected, a bit of capacitive air coupling but its working basically. LOL

[moodz]

multitone quadrature waveforms implemented ...

[moodz]

CEO ?

[ivconic]

Beware Paul!

[moodz]

....getting somewhere .. porting the FCMD into a STM32H750 chip with onboard 16 bit ADCs operating in oversampling mode.
Here is a pic of the ADC performance at ( 3.6 Mhz smps at 16x oversample ).

The DAC is outputting frequency tones.

The tones shown are 14 Khz 28 Khz and 42 Khz ... everthing is synchronous.
The noise floor is -96 db ... I can live with that.
The chip is connected via its USB port to a PC running a python script to show the FFT. Python is not fast so it is giving the wrong SPS rate ( its much faster ).

AI wrote all the code .. I just told it what to do.

[moodz]

Further to the kind of unstated purpose of this project ( developing metal detector code with AI ).

I asked the AI what language it would use if two AIs were working together. Somewhat surprisingly it came up with a complete specification for a language simply called 1 ( ie the number "1" )
It also told me that because computer languages were written for humans they are somewhat confusing :
So the "1" language has implicit defined blocks ( input, output, requirements, implementation ) and all of the syntax code can be treated as program variables ( that means the code can modify itself ... if it wants to )

In about 1 hour it developed the complete toolset :

Theres a python bootstrap compiler, native compiler, VM, documentation and examples on my github site :

https://github.com/haxidermist/1lang