16F876A Pulsin issues

[Bobbo_ZA]

I feel like such a rookie, :-) I should have look at more of my previous code, :-)

pulsin gr,1,g	
pulsin rx,1,P          
low throttle
pulsout throttle, P

Thanks exactly what I had in a previous project, :-)

Can't wait to get home now, :-)

Will post pics once I have it programed and working, hope to build up a nice multi function test unit - once thing im still investigating is how to measure the battery voltage of a 4 cell flight pack (nicad or nimh) with a 250ma load, im using the units 5.02V regulated supply as a reference but not quite sure if I could just give the flight pack's V to the ADC through a resistor and work from there? 4 Cell fully charged will give me 5.6V and I dont know what the ADC does when the voltage is higher than the reference V, also could the pic handle the extra .6V?

On a side note I'm still hunting down a case for my LM35 project, finally got some ally tubing to house the sensor, just need to find a nice case for the PIC and water proof it, :-) (will post pics etc as well once complete)

Kind Regards
rob

[Acetronics2]

Hi, Rob

Consider all inputs are clamped to Vcc + .6 v ... ( take care: clamps diodes are very Weeeeeeak ! )

so, the best is not to have more than Vcc ... or use strong external clamp diodes ( 1 N4148 i.e )

but analog inputs can rise to Vref + 2v ... not forgetting Vcc+.6v is an absolute maximum ...

Alain

[Bobbo_ZA]

Would adding a bigger load to the pack solve the problem? A bigger load should pull the cells down to 1.2v per cell to give me a max of 4.8V on a fully charged pack? perhaps a 500ma load?

[Acetronics2]

Bad Idea ...

just use a voltage divider in the input ...

1/2 is the easiest to find ( 2 equal 1% resistors ) ...
2/3 is still easy ( 1 k and 2k resistors @ 1%)

Installing a load that can draw 300 - 400 mA on demand is rather a good thing ...

But think regulator doesn't output EXACT 5.000 v ... so measure it and enter value as a parameter for calculations ...

Alain

[Bobbo_ZA]

I have an idiot grin on my face, :-) im making some really good progress, I have the pulse in now displaying on the screen (strange from a JR Rx Im getting a range from 560 - 990 from the pulsin) and have the ability to jump to a servo test (sweep from side to side) at the push of a button, :-)

My ADC is sort of working, with the voltage divider I'm getting 2.54V on my DMM, however if I display the ADC input Im only seeing 2 and not the .54 (obviously this will be multiplied by 2 once i get the decimals). I have tried:

lcdout $FE, $C0+8, dec volt

and 

lcdout $FE, $C0+8, # volt

but still only get the first digit. Is this due to the ADC VAR being a "WORD"

Volt    Var     WORD
.
.
.
ADCIN 4, volt
.
.
.

My Vref from the regulator is 5.00V on my DMM

Not sure im getting this whole ADC concept, I;ve read another one of Melanie's posts and from what I can work out, my RAW ADC in variable should be as follows:

if my Vref = 5.00 then if my ADCIN was exactly 5.00V the ADC result would give me 1024, however I am giving a ADC of 2.54 I should get a value in the variable of 520? however I am displaying a single digit "2" on the LCD with the code above, not sure how to do the math on this.

[Bobbo_ZA]

Ah, ok, finally, im a git, :-)

Im now reading a 520 adc value with the battery on and the DMM measuring 2.54 (Needs to be multiplied by 2 to reverse the voltage divider effect).

Err, something not right, im missing something with the math:

    ADCIN 4, volt                  ' Read AN4 into temp variable
    Vin = (5*volt/1024)       ' Convert to voltage assuming 5.00 = 1024

lcdout $FE, $C0+8, dec Vin,".",dec2 Vin,"V"

pulling out many hairs, :-( my biggest issue is that even in school my maths was not great, spose thats why Excel was invented, for people like me, :-)

[Bobbo_ZA]

just not getting the decimal places now, :-(

Latest attempt

ADCIN 4, volt                  ' Read AN4 into temp variable
volt = volt * 2
Vin = (5*volt/1023)
Vind = (volt // 1000) / 10 'millivolts?

lcdout $FE, $C0+8, dec Vin,".",dec2 Vind,"V"

Time to pack it in for the night, work tomorrow, fairly good progress, just the decimal points to figure out.

Kind Regards
Rob