Reading sensors with 3.3v(beginner)

[tacbanon]

Hi, I did some testing but this time using PIC16F887 on 5v just to isolate the specific program which is to read the accelerometer module on 3.3v..using the following code.

'' Program Start Here ''

DEFINE osc 20           ' We're using a 4 MHz oscillator
DEFINE ADC_BITS 8       ' Set A/D for 8-bit operation
DEFINE ADC_CLOCK 3      ' Set A/D clock Fosc/8
DEFINE ADC_SAMPLEUS 50  ' Set A/D sampling time @ 50 uS

ANSEL = %11111111 ' Make AN0-AN7 Analog
ANSELH= %00000000 ' Make AN8-AN13 digital

accx var byte
accy var byte
accz var byte

DataOut var Byte
DataOut = 0

'    PORT setting
    '    ============
         '
          TRISA = %11111111   ' Set PORTA to all input
          ADCON1 = %0001001  ' Set PORTA.0,1,2,4,5,6 = A/D, PortA.3 = +Vref
          TRISC = %10000000        ' RC.7 => USART RX pin set to input
                                ' all other pin set to output
         'OPTION_REG = $7f       ' Enable PORTB pull-ups
                                '
         TRISB=%00000000                ' RB<7:0> set to output
         TRISD=%00000000
         
'    USART setting
    '    =============
         ' Since we will not use HSERIN/HSEROUT, we must
         ' write directly to internal PIC register
         ' 
         TXSTA=$24              ' enable transmit and SPBRGH=1
         RCSTA=$90              ' Enable USART and continuous receive
         SPBRG=129          ' BAUD RATE = 9600 BAUDS

'    Interrupt definition
    '    ====================
         '
         PIE1.5   =1            ' enable USART receive interrupt
         INTCON.6 =1            ' enable peripheral interrupt
    
    '    Alias definition
    '    ================
         '
         RCIF       var PIR1.5   ' receiver interrupt
         UserLED1   var PORTB.0  ' the LED who show a 'running process'
         UserLED2   var PORTB.1  ' the LED1 that user want to control
         UserLED3   var PORTB.2  ' the LED2 that user want to control
        
         
    '    Variable definition
    '    ===================
         '
         Delay     var word     ' 
         DataIn    var byte     ' use to store RCREG content
         Discard   var byte     ' use to erase RCREG register
        
    '    Hardware/software initialisation
    '    ================================                                                                                                                                                         
         '
         PORTB=0                ' clear PORTB   
         PORTC=0                ' dlear PORTC      
         on interrupt goto USARTInterrupt


   
    PAUSE 500           ' Wait .5 second

loop1:
    ADCIN 0, accx: ADCIN 1, accy: ADCIN 2, accz
    Hserout["Data receive: X:",Dec accx," Y:",Dec accy," Z:" ,Dec accz, 13] 
    Pause 200
   
    GOTO loop1               ' Do it forever

    END
    
disable interrupt
USARTInterrupt:
    '    Here's the interrupt routine who will make the user
    '    much happy by giving him the feeling to have the 
    '    control on the machine when the status of the user
    '    LED will change
    '
    RCSTA=0                     ' Disable serial port AND
                                ' clear possible error (FERR,OERR)
                                
    datain=RCREG                ' Get data
                                
    while RCif                  ' wait untill the RCREG is empty
          discard=RCREG         ' by reading it and store result in a
    wend                        ' don't care variable
                                
    select case datain          ' What to do with that data???
                                
           case "1"            ' User selection = 1
                userled1=1       '      => Enable the LED
                                
           case "2"           ' User selection =2
                userled1=0       '      => disable the LED
           
           case "3"           ' User selection =2
                userled2=1       '      => disable the LED
                
           case "4"           ' User selection =2
                userled2=0       '      => disable the LED
                
           case "5"           ' User selection =2
                userled3=1       '      => disable the LED
                
           case "6"           ' User selection =2
                userled3=0       '      => disable the LED
                
           case "a"           ' User selection =2
                PortB=%00000111       '      => disable the LED
           case "d"           ' User selection =2
                PortB=%00000000       '      => disable the LED   
                

                                
           end select           
    RCSTA=$90                   ' Re-enable the serial PORT AND
    resume                      ' get out of here
enable interrupt

I have the following reading:


and I think I'm not getting the right output...what might causing it?

Kind regards,
tacbanon

[tacbanon]

Hi all, I'm gonna try to use an i2c accelerometer but from where I'm located (province) it will take some days to arrive...then post here my inquiries .
I'm gonna try to move on to another sensor(barometric) while waiting for the accelerometer.

Regards,
tacbanon

[Ramius]

Hi Tacbanon!
I would be very interested in your results with your accelerometer as I am in need of a tilt sensor (pitch and roll). I see you are looking for a barometric sensor and you may wish to look at http://www.picbasic.co.uk/forum/showthread.php?t=16457 which is a depth sensor which should work for altitude as well. If nothing else there is a 3.3v to 5.0v level converter that may be useful for your project.

Best, Ed

[tacbanon]

Greetings Ramius!
Thanks for your interest, and very thankful for the guide, and I will try this(3.3v to 5.0 converter).

regards,
tacbanon