chance pi build

[baum7154]

@baum7154
technically it is not possible make VDI samples gap below 10us (even on 2,7MHz ADC clock). Real VDI samples gap in the v121 was 32,5us. (20us took conversion with 1,7MHz ADC clock + fixed in the code 12,5us)
More details in the changelog.txt[/QUOTE]
--------------------------------------------------------

dantech,

I am a bit confused by the phrase 'VDI samples gap'. Please explain what a VDI samples gap is. Are you talking about the main sample window width or possibly the window duration?

When I look at the scope trace of my V1.2.1 Chance the main sample delay at a minimum Guard Interval setting of '10', the sample delay with the original clock of 11.0592mHz, starts about 9us after the coil begins its flyback. The duration or width of the main sample window is 12.5us, after this the window closes. I do not see any other real delay of 20us on the scope.

Also using Google Translator I am unable to open your link and there is a message that there is no file.

Thanks

Dan

[dantech]

Use google translator: polish to english

[6666]

I take it the change log is not in English.

[dantech]

v178
http://chomikuj.pl/dantech/Chance+PI

Important pieces of information inside changelog.txt


At the moment the compiler makes two releases for m8 and m328 at once. This is the same code practically but... on m328 I see strange behaviour on right edge of VDI pointer.
At the moment I do not have idea how to relove it.

@baum7154
technically it is not possible make VDI samples gap below 10us (even on 2,7MHz ADC clock). Real VDI samples gap in the v121 was 32,5us. (20us took conversion with 1,7MHz ADC clock + fixed in the code 12,5us)
More details in the changelog.txt

[baum7154]

Hi Dantech,

Is the sample window now 6us wide instead of 12us? I do understand that sample delay is selectable from 1 through 99us. Is there a way with the greater memory of the 328P microcontroller to allow the sample width to be user selectable? I ordered my 328P chips yesterday and should have them next week.

Thanks,

Dan

[dantech]

v177
http://chomikuj.pl/dantech/Chance+PI

A lot of improvements. eg ADC is clocked now 2,76MHz instead of 1,38MHz. This change makes entire sample process time 6us instead of 12us. Delay setting in the menu have real values regarding conversion times.
Look into changelog.txt

[baum7154]

Dantech

We agree. So the PWM is now eliminated but the fixed width pulses still remain. I appreciate the information you are providing through your insight into the original firmware

Thanks,

Dan

[dantech]

Here are timings from v84. Ones are quite similar to v121 timings (no prepulses and 20 PWM pulses instead of 16 ones)
Look onto the coil current growth during the even cycle.
Like I said earlier, Fandy has told me that PWM solution does not work.
My tests in the field confirm it.


Regarding the word "damping".
Probably it is question of translation. From my point of wiev the word "damping" means "attenuation" or even "shortening" in some cases.

[baum7154]

[QUOTE=dantech;221444]I do not think so.
Notice that the even cycle has 16 PWM pulses but Q9 is switched on during 15 pulses only. In that phase (Q9 is on - additional damping)
coil current grows but without generating pulse.
In the last 16th PWM pulse Q9 is opened (the coil is not additionally damped) , the coil current stops growing and then when coil is switched off the pulse is generated.
So, main condition to generate pulse is Q9 switched off. When Q9 is switched on there is no pulse but the coil current growth only.
More or less...
It looks like some power pump. I have checked total power consumption and despite the entire even PWM cycle takes nearly 600us the power consumption
is the same as only one 240us pulse instead of mentioned PWM! It seems that the PWM solution allows to reach higher coil current without excessive power
consumption
----------------------------------------------------------------
dantech ,

We are saying the same thing with one exception, Q9 is not 'damping' the coil. Because it is shorting the coil it is keeping (storing) the energy in the coil. Damping is the opposite action of causing the coil to release its energy more quickly. It makes sense that Q9 is not on when flyback is intended and it is then that the damping resistors R13 & R16 in combination do their job of coil damping. This is why optimizing the value of R13 is so important in getting the coil to release energy as rapidly as possible in order to detect small/fast targets especially at sample delays below 10us.

Regards,

Dan

[dantech]

I do not think so.
Notice that the even cycle has 16 PWM pulses but Q9 is switched on during 15 pulses only. In that phase (Q9 is on - additional damping)
coil current grows but without generating pulse.
In the last 16th PWM pulse Q9 is opened (the coil is not additionally damped) , the coil current stops growing and then when coil is switched off the pulse is generated.
So, main condition to generate pulse is Q9 switched off. When Q9 is switched on there is no pulse but the coil current growth only.
More or less...
It looks like some power pump. I have checked total power consumption and despite the entire even PWM cycle takes nearly 600us the power consumption
is the same as only one 240us pulse instead of mentioned PWM! It seems that the PWM solution allows to reach higher coil current without excessive power
consumption!
But in fact I do not see any advantage during the detector work in the field. Opposite, I see some VDI instability with PWM solution.

Of course I can be wrong


Baum7154.
I agree and I use since 2-3 weeks the TL1054 with gel battery.
Every my software release makes proper state on pin28 (ICL7660/TL1054 power control) to give compatibility with original hardware.

At the moment I am almost on the edge of mega8 possibilities and mega328 releases are quite near

[baum7154]

[QUOTE=dantech;221417]I shall read this thread more carefully again.
Facts from code below:
1. 16 pulses acts only in the even cycle. During entire even cycle Q9 is closed and coil does not transmit entire power. So I do not thing that Q9 circuit + PWM makes something useful.
At the moment I switched off PWM and use one pulse only. I do not see any difference in the field. Fandy told me in the past that Q9 circuit does not work in fact.
-----------------------

Q9 can be closed during the entire even cycle as you say because diode D6 conducts only in the fly back polarity which is the opposite polarity of the transmit pulse polarity.

Regards,

Dan

[6666]

V1x are for mega8 v3x are for mega328.

Just for laughs how about adding the type of chip to the hex file name, might save a bit of confusion.

[baum7154]

Have in mind that ATmega8 flash memory size makes huge limit to further software development.
I am ready to "hop" onto pin compatible Atmega328P.

----------------
I agree and will order a few ATmega328P chips. I am also going to order a few LT1054 to replace the 7660 as suggested by Qiaozi as my 10 Cell Nimh battery packs charge to 13.9 vdc too.

Thanks dantech,

Dan

[dantech]

V1x are for mega8 v3x are for mega328.

[Spyke]

Have in mind that ATmega8 flash memory size makes huge limit to further software development.
I am ready to "hop" onto pin compatible Atmega328P.

If I understand right, the last versions are all for 328? Or are they for both (8 and 328 )?