Nasty PBP math help ?

[Ingvar]

Hi Ingvar, long time since we last conversed....

Time flies when you're having fun

Your genius has not deminished and I'm humbled by your math skills.

*LOL* You just made my day. Now i don't need to feel bad when i take a few extra beers tonight. It seems obvious that I kill off the weaker braincells first ....

I ran a couple of RAW values on my calculator, YES you are spot on V = 12e6/RAW comes out right. If you knew how much time I spent trying to work that out myself you'd laugh your head off at me :-)

Nop, i wouldn't laugh at people who're struggling. People tend to get pissed off by that .... atleast i do.

The 12000000 figure is the system clock frequency BTW, but I suspect you guessed that one.

The thought crossed my mind ...... and again ....... and stuck.

I'd better go digest your code for larger than 15 bits.

Don't forget to chew, it's difficult to perform a Heimlich maneuver from half across the globe.

Thanks again. Look me up if you ever come visiting Australia

No worries, mate.

[Martin]

Hi Ingvar, hope you enjoyed the beers.

The project is running fine on the bench now, got most of the full unit is assembled too, should be finished tonight. Then wait for a fine day to go to field testing.

I do have a quick question, as I'm running the 15bit or less code currently so my accuracy is to +- 1 FPS (last digit).

Can DIV32 give a remainder so rounding can be used ? Like //.

Martin

[Ingvar]

Hi Ingvar, hope you enjoyed the beers.

I sure did, again and again and again and ..... i just hated myself the day after.

I do have a quick question, as I'm running the 15bit or less code currently so my accuracy is to +- 1 FPS (last digit).

Can DIV32 give a remainder so rounding can be used ? Like //.

You can increase the resolution by 10 quite easy. Just preload the registers with 120000000dec(=07270E00hex) instead. You could then do rounding on that.

    R0.HIGHBYTE = $07
    R0.LOWBYTE = $27
    R2.HIGHBYTE = $0E
    R2.LOWBYTE = $00 
    Velocity = DIV32 Raw
    Velocity = (velocity + 5 )/10

Just remember that the accuracy decreases with higher speeds. Not much use for tenths of ft/s when the raw data can't be more accurate than 3 ft/s.
Raw = 2000 gives 6000 ft/s
Raw = 2001 gives 5997 ft/s

/Ingvar