ADC_IN statement

[Russ Kincaid]

I am elated that my IF - Then compiles OK, but I am trying to use the A/D converter and I get a "syntax error" on the ADC_IN statement. I looks just like the example in the manual to me. Here is my program:
REM DEVICE = 12F675
REM USE INTERNAL OSCILLATOR, OUTPUT IS ON GP4 (PIN3)
REM CONFIGURATION: INTOSC CLOCKOUT, WDT DISABLED, PWR UP ENABLED,
'MCLR = INPUT PIN,BROWN OUT DISABLED, NO PROTECTION
REM CLOCK OUT ON PIN 3 (GP4)
REM CHARGER SWITCH ON PIN 7 (GP0)
REM A/D INPUT ON PIN 4 (GP3)
REM GREEN LED ON PIN 2 (GP5)
ADCON0 = %00001101 'LEFT JUSTIFIED, VDD REF, CHANNEL 3, A/D INITIALLY OFF
ANSEL = %01001000 'CLOCK IS FOSC/4, INPUT TO GP3
TRISIO = 0 'ALL OUTPUTS EXCEPT GP3
GPIO = 0 'ALL OUTPUTS INITIALLY LOW
DEFINE OSCCAL_1K 1 'SAVES OSCILLATOR CALIBRATION
DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 5 'INTOSC_CLOCKOUT?
DEFINE ADC_SAMPLESUS 50 '50 MICROSECONDS SAMPLE TIME
VOLT VAR WORD
OLDVOLT VAR WORD
GREEN VAR GPIO.5
SWITCH VAR GPIO.0
START:
LOW SWITCH 'TURNS ON CHARGER
PAUSE 60000 'DELAY 1 MINUTE
HIGH SWITCH 'TURN OFF CHARGER
ADC_IN 3,VOLT 'SAMPLE CHANNEL 3, STORE BATTERY VOLTAGE
IF VOLT < OLDVOLT THEN
STOPCHG
ENDIF
OLDVOLT = VOLT
GOTO START
STOPCHG:
HIGH GREEN
STOP
END

[Acetronics2]

Hi Russ

Just write "ADCIN" ( no underscore ...)

<< loop: ADCIN 0, adval ' Read channel 0 to adval >>



Regards
Alain

[skimask]

If this is a NiMH charger controller type thing, there's no reason to shut off the charger to check your battery voltage. But, instead of taking a single reading and comparing that to your old reading, I'd take a load of readings over a minute, add them up, and then see if the new 'summed reading' is less than the old 'summed reading'. That way, any voltage drops due to mains power fluctuations, ripple in the power supply, etc. should be compensated for. Try this instead:

adcon0=$d:ansel=$48:trisio=0:gpio=0
DEFINE OSCCAL_1K 1 'SAVES OSCILLATOR CALIBRATION
DEFINE ADC_BITS 10
DEFINE ADC_CLOCK 5 'INTOSC_CLOCKOUT?
DEFINE ADC_SAMPLESUS 50 '50 MICROSECONDS SAMPLE TIME
volt var word : oldvolt var word:green var gpio.5:switch var gpio.0:summedvolts var word : oldsummedvolts var word:sumcounter var byte:fudgefactor var byte:fudgefactor=100:low switch
START:
pause 60000:for sumcounter=1 to 64:adcin 3,volt:summedvolts=summedvolts+volt:next sumcounter:if ( summedvolts - fudgefactor ) < oldsummedvolts then stopchg
oldsummedvolts=summedvolts:summedvolts=0:goto start
STOPCHG:
high green:stop
end

Another problem the original is that there is no 'slop' built into it. One ADCIN count less, and the charger stops. That's why I added the 'fudgefactor' to it.

[mister_e]

IF VOLT < OLDVOLT THEN
STOPCHG
ENDIF

should be

IF VOLT < OLDVOLT THEN STOPCHG

[Russ Kincaid]

Thanks, Alain, it is working now.
Steve: you are right, my code didn't work, but yours doesn't either! What works is:
IF volt "<" oldvolt THEN
GOTO stopchg
ENDIF

Thanks, all.

Russ

[mister_e]

<table><tr><td></td><td>

IF volt "<" oldvolt THEN

well unless we don't use the same compiler, it must return a syntax error as well
</td></tr></table>

If something=something_else then Label

is the same thing as

If something=something_else then 
    goto Label
    endif

At least here... so that's weird.

DEFINE ADC_SAMPLESUS 50

the only valid syntax i know is

DEFINE ADC_SAMPLEUS 50

Yeah, it doesn't return any syntax error... it's just ignored. Fortunately there's some default value
pbppic14.lib

;****************************************************************
;* Default Adcin values                                         *
;****************************************************************

    ifndef ADC_BITS		; ADC number of bits
ADC_BITS EQU 8
    endif
    ifndef ADC_CLOCK		; ADC clock source = rc
ADC_CLOCK EQU 3
    endif
    ifndef ADC_SAMPLEUS		; ADC sample time in microseconds
ADC_SAMPLEUS EQU 50
    endif

[Acetronics2]

Hi, Skimask

" If this is a NiMH charger controller type thing, there's no reason to shut off the charger to check your battery voltage"

You're TOTALLY WRONG !!!

...

just look at ALL NiMh and NiCd "reflex" chargers ... why stop charging when sampling voltage then ... ???

good question !!!

Alain