16f88 - pin RA4 as analog input

[savnik]

I have the below code with 16f88 , and i want to know if may use the pin RA4
as analog input.
I want to read the voltage from a tuner.The range of voltage is 0.5-3.5V.

            CMCON = 7                                  ' PortA = digital I/O
             
	DEFINE LCD_DREG	PORTB	'Selection of the port B
	DEFINE LCD_DBIT 0	    'Selection one RB0 with RB3
	DEFINE LCD_RSREG PORTA	'RS on port A
	DEFINE LCD_RSBIT 2	    'RS on RA2
	DEFINE LCD_EREG	PORTA   'E on port A
	DEFINE LCD_EBIT 3	    'E on RA3
	DEFINE LCD_BITS 4		'Mode 4 bits
	DEFINE LCD_LINES 2	    '2 lines

	DEFINE I2C_SCLOUT 1
	
	PAUSE 500
	
' ** DEFINITION OF THE ENTREES - EXITS

' Exits I2C

	SCL var PORTA.1         'SCL on RA1 (pine 18)
	SDA	var	PORTA.0		    'SDA on RA0 (pin 17)

' Boutons

	UP	    var	PORTB.6		'increase the frequency (on RB6)
	DOWN	var	PORTB.7		'decrease the frequency (on RB7)
	CH_PAS	var	PORTB.5		'Change the step of synth (on RB5) 
 
	
	Input	UP			    'Up and Down are entries
	Input	DOWN
	Input	CH_PAS

[sayzer]

Hi Savnik,

RA4 can be used as analog input as data sheet says (16F88).

In this case, you need to add ANSEL = %00010000 to your code.
ANSEL = %00010000 will set RA4 as analog and all others as digital.
Make sure you set RA4 as an input pin prior to ANSEL.


You may need to work around CMCON a little.


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[savnik]

i have add this in my code:

    CMCON = 7               ' PortA = digital I/O
	ANSEL = %00010000       ' Will set RA4 as analog and all others as digital
    ADCON0 = %11100001	   
    ADCON1 = %10000010 	   
    adval   var Byte		     'Create adval to store result
    IN	    var	PORTA.4
    Input	IN

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

	    Lcdout $fe, 1   				' Clear LCD
        Lcdout "Value: ", DEC adval		' Display the decimal value  

        Pause 100       				' Wait .1 second

        Goto loop       				' Do it forever
        End

need to add this;

   
    Define  ADC_BITS        8     	' Set number of bits in result
    Define  ADC_CLOCK       3     	' Set clock source (3=rc)
    Define  ADC_SAMPLEUS    50    	' Set sampling time in uS

but show on LCD Value:3 continues

[Darrel Taylor]

Read from AN4

ADCIN 4, adval

[savnik]

Read from AN4

ADCIN 4, adval

Thank you.
At 0 volt show value: 0 and at 5 volt show value:3
How i can at 0 volt show value: 0 and at 5 volt show value: 50 or 100 or something greater from 3;
Is easy to show the level as bargaph on LCD;

[sayzer]

Post the schematic.
Let us see your ADC reading part also.


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