2nd Chance PI

[dantech]

At the moment the code is practically rewritten by me, timings are changed and some hardware changes are issued also. Since now my releases
will be called "2nd ChancePI" to distinguish from base project called "Chance PI"

I have to point out that every my software release has roots in the project called ChancePI/AndyF.

Thank you AndyF for you hard work.


2nd ChancePI v001
http://chomikuj.pl/dantech/2nd+ChancePI

[ivconic]

At the moment the code is practically rewritten by me, timings are changed and some hardware changes are issued also. Since now my releases
will be called "2nd ChancePI" to distinguish from base project called "Chance PI"

I have to point out that every my software release has roots in the project called ChancePI/AndyF.

Thank you AndyF for you hard work.


2nd ChancePI v001
http://chomikuj.pl/dantech/2nd+ChancePI

Splendid job!
I am interested to see the details, can you write changelog in English?
I see 11.0592 quartz on schematic... is it easy obtainable?
What are the chances your code to be adapted for Atmega328P and 16Mhz clock?
Cheers!

[dantech]

You can use pcb from original ChancePI. My hardware is a little bit simplified but PCB should be compatible (empty places for parts).
New schematic inside .zip file

At the moment I have some troubles with compiler and atmega328. the same code compiled for m328 has some problems to keep proper timings.
Investigation in progress...

You can easily translate changelog.txt from Chance PI by google
I do not plan use 16MHz crystal because one do not allows "nice" dividers for timers. Because of dividers issue the crystal 11,0592 is very popular and cheap.

[ivconic]

You can use pcb from original ChancePI. My hardware is a little bit simplified but PCB should be compatible (empty places for parts).
New schematic inside .zip file

At the moment I have some troubles with compiler and atmega328. the same code compile for m328 has some problems to keep proper timings.
Investigation in progress...

You can easily translate changelog.txt from Chance PI by google
I do not plan use 16MHz crystal because one do not allows "beauty" dividers for timers. Because of dividers issue the crystal 11,0592 is quite popular.

Oh i understand what are you saying!
"Mathematics" with interrupts at 328p is pretty awkward. Lot of troubles.
One of the tricks to do the job is exactly to "trim" the main clock with proper quartz and match the "mathematics" inside the code!
This project can gain a lot on popularity if it can be easy transfered to Arduino platform.
And there you have 16Mhz clock. A problem!
I am not informed; if quartz can be replaced at Arduino directly?
Anyway... this is interesting enough as it is now.

[dantech]

Exactly! Do you have any knowledge how to bite m328?

For example the C++ instruction delay_us(30) on mega8 makes exactly 30us delay but on mega328 makes 33us!
I see that entire execution time on mega328 has minimal delay. Unfortunatelly the project is time sensitive.
At the end entire timing on mega328 goes to the deep forest...
I do no have any idea how to fight with it?

BTW. The next crystal with "nice" timer dividers is 18,432 but unfortunatelly using it will clock MCP3201 slower (2,30 MHz ADC clock - divider 8 for ISP) than 11,0592 (2,76 MHz ADC clock - divider 4 for ISP)

More necessary files is added to my repository
http://chomikuj.pl/dantech/2nd+ChancePI

[dantech]

@ivconic

Do you think I should try to increase F_CPU to eg. 12,35MHz value to cheat compiler for mega328?

[ivconic]

Exactly! Do you have any knowledge how to bite m328?
For example the C++ instruction delay_us(30) on mega8 makes exactly 30us delay but on mega328 makes 33us!
I see that entire execution time on mega328 has minimal delay. Unfortunatelly the project is time sensitive.
At the end entire timing on mega328 goes to the deep forest...
I do no have any idea how to fight with it?
More necessary files is added to my repository
http://chomikuj.pl/dantech/2nd+ChancePI

My knowledge is still at novice's level. I am still learning.
But i already tasted all the "beauty" of programming the 328P for delicate timing tasks!
For precise timings you will need to switch on assembler and forget about C language.
Good news though is in fact that you can mix assembler and C when necessary.
All depends on what tool are you using for writing code.
That's why i suggested Arduino, its IDE is allowing you all the possible "acrobatics".
I think Joop our colleague from forum here can say much more than me on that subject.
Let's invite him here to join.

BTW Joop's threads which i find as very informative:
http://www.geotech1.com/forums/showt...ted-to-arduino
http://www.geotech1.com/forums/showt...metal-detector

[eclipse]

There is wider option of N channel Mosfets, especially with low Rds/High Vds, any reason why you keep the P channel Mosfet?

[dantech]

This is inherited from ChancePI. Compatibility with old PCB

[dantech]

mega328 release is published. The compiler work worse with very short delays but the precision is still accurate

[ivconic]

mega328 release is published. The compiler admire worse with delays but the precision is still accurate

[dantech]

Should be "work" worse instead of "admire"

[dantech]

Hi,
Detection range comparison.

2nd Chance PI versus Garret ACE 250 !

Part 1
https://youtu.be/7vIdAO51E_c

Part 2
https://youtu.be/uYxHxEehncY

2nd ChancePI has the range better than ACE 250 about 25-30%

I have set on 2nd Chance PI 3 bar signal masking. This is useful barrier to prevent unwanted signals and discrimination need this signal level to work well.
On the ACE 250 I have set sensitivity -2. This is also optimal setting to avoid unwanted signals.

I do not want to sets fictive and useless detection range


By the way I have to say that discrimination is more accurate in the 2nd Chance PI. Maybe I shall do next comparison test

Tested objects
- Gold ring
- silver ring
- beer bottle cap
- aluminium square 10x10 mm from beer can wall
- present pistol bullet
- bullet shell - mauser from 1901 and present
- one US cent coin
- polish old communist 50 gr aluminum coin
- polish present 2 gr coin
- polish present 1 gr coin
- present threaded brass pipe joint
etc...

Of course 2nd ChancePI has huge advantage - static work

[dantech]

v002
http://chomikuj.pl/dantech/2nd+ChancePI

[dantech]

v003