A/D conversion with PIC18F67J50

I am having a heck of a time getting A/D conversion to work with the pic18f67j50. I know I am probably missing something basic from rtfm.

In desperation, I have tried to copy some C demo code (that is working on my hardware), and translate the basic setup to picbasic pro. My hardware is the Olimex PIC_LCD3310 located here http://www.olimex.com/dev/pic-lcd3310.html

I have the display working. Right now I just have an analog operator issue.

Here is my setup from the include file:

Code:

---

    else
        LIST
        LIST p = 18F67J50, r = dec, w = -311, w = -230, f = inhx32
        INCLUDE "P18F67J50.INC"        ; MPASM  Header
        CONFIG XINST = OFF
        CONFIG STVREN = OFF    ;added
        CONFIG WDTEN = OFF    ;added
        CONFIG CP0 = OFF    ;added
        CONFIG IESO = OFF    ;added
        CONFIG FCMEN = OFF    ;added
        CONFIG CCP2MX = DEFAULT    ;added
        CONFIG PLLDIV = 5
        CONFIG WDTPS = 32768 ;was 512
        CONFIG CPUDIV = OSC1
        CONFIG FOSC = HSPLL
        CONFIG MSSPMSK = MSK5  ;added
        NOLIST
    endif

---

And here is one of my attempts at getting A/D out of it:

Code:

---

DEFINE OSC 48

include "modedefs.bas"
include "LCD_3310.pbp"

TRISD = 0
PORTD.0 = 1  'turn on g sensor
PORTD.1 = 0  'select scale for g sensor
PORTD.2 = 0  'select scale for g sensor


TRISA = %00000111  'set porta.0, 1, and 2 as inputs
TRISB = 0
CM1CON = 7
CM2CON = 7
TRISC = 0
TRISE = 0
ADCON0 = %00000001      'turn on adc
ADCON1 = %00000010      'fosc/32 ??
'am I translating c language ADCON1=0x10 above correctly?

resx var word
x var word
y var word
z var word
adval var word

x=0
y=0
z=0
adval = 0

PORTD.0 = 1  'turn on g sensor (again)
'*************************************************
@bsf WDTCON,ADSHR  ;set shared address SFR with WTCON<4> - is this right?
ADCON0 = %11111110  ' channel with a 0 is analog input, all others digital
@bcf WDTCON,ADSHR
ADCON1 = %10111110  'right justified, AD=20AD, A/D clock=fosc/64
ADCON0.0 = 1        'turn on adc

ADCON0.2 = 0        'channel select bit CHS0(should already be a 0)
ADCON0.3 = 0        'Channel select bit CHS1(should already be a 0)


start:
    Pause 500              ' Wait .5 second
loop:                ADCON0.1 = 1                                        'Start Conversion
adval = 0                                  'clear result word
notdone:        pause 5
                        if ADCON0.1 = 1 Then notdone        'wait for low on bit-2 of ADCON0, conversion finished

                        adval.highbyte = ADRESH                        'move HIGH byte of result to adval
                        adval.lowbyte = ADRESL                        'move LOW byte of result to adval
           
            ADCON0 = %00000000              'turn off adc
                   
            'Lcdout $fe, 1                                  'Clear screen
                'Lcdout "Value: ", DEC adval        'Display the decimal value 
@ PrintStr 0,0, "Z= "                      ;display on Nokia 3310
@ PrintVar 24,0, _adval                    ;display result on 3310
                Pause 100                                      'Wait .1 second

                      'Goto loop                                      'Do it forever
                End

---

This is an (apparently BAD) attempt at making it look almost just like:

Code:

---

#pragma config XINST    = OFF      // Extended instruction set
        #pragma config STVREN  = OFF      // Stack overflow reset
        #pragma config PLLDIV  = 5        // (20 MHz crystal used on this board)
        #pragma config WDTEN    = OFF      // Watch Dog Timer (WDT)
        #pragma config CP0      = OFF      // Code protect
        #pragma config CPUDIV  = OSC1      // OSC1 = divide by 1 mode
        #pragma config IESO    = OFF      // Internal External (clock) Switchover
        #pragma config FCMEN    = OFF      // Fail Safe Clock Monitor
        #pragma config FOSC    = HSPLL      // Firmware must also set OSCTUNE<PLLEN> to start PLL!
        #pragma config WDTPS    = 32768
//      #pragma config WAIT    = OFF      // Commented choices are
//      #pragma config BW      = 16      // only available on the
//      #pragma config MODE    = MM      // 80 pin devices in the
//      #pragma config EASHFT  = OFF      // family.
        #pragma config MSSPMSK  = MSK5
//      #pragma config PMPMX    = DEFAULT
//      #pragma config ECCPMX  = DEFAULT
        #pragma config CCP2MX  = DEFAULT

;---------------snip

      ////////////MMA pins configuration - Sleep mode disabled///////////////////////////////
        TRISDbits.TRISD0=0;
        PORTDbits.RD0=1;
        //GS1 =0
        TRISDbits.TRISD1=0;
        PORTDbits.RD1=0;
        //GS2=0
        TRISDbits.TRISD2=0;
        PORTDbits.RD2=0;
       
        TRISAbits.TRISA0=1;
        TRISAbits.TRISA1=1;
        TRISAbits.TRISA2=1;
        //ADC module enable
        //ADCON1=0x10111110;        //right-justified; AD=20AD;A/D clock=fOSC/64   
          ADCON0=0x01;        //Enable ADC module
        ADCON1=0x10;     
      ////////////////////////MMA measure/////////////////////
        resx=0;
        x=0;
        y=0;
        z=0;
        sym=0;
        PORTDbits.RD0=1;  //MMA SLEEP MODE disable
//****************************************************************************
        ANCON0bits.PCFG0=0;  //AN0 - analog input
        ADCON1=0b10111110;        //right-justified; AD=20AD;A/D clock=fOSC/64   
      //  ADCON1=0x10;
        ADCON0bits.ADON=1;    //Enable ADC module, AVdref, AVss
        //set Z-axis measure
        ADCON0bits.CHS0=0;
        ADCON0bits.GO=1;            //BSF ADCON0,GO ;Start conversion
        while(ADCON0bits.GO);        //  BSC ADCON0,GO ;Is conversion done? ;  GOTO $-1 ;No, test again
        resz=ADRESL;
        z=ADRESH;
        z=(z<<8)|resz; 
        resz=z;     
        ADCON0=0x00;      //stop ADC
//****************************************************************************

---

If someone could point out what an idiot I am, that would be great!

Thanks!

Walter

I believe it's the ADCON0 = %00000000 'turn off adc

You probably get a reading the first loop through.
But for all loops after that, the A/D module is turned off.
<br>

Thanks Darrel,

I commented out my ADCON0 = %00000000 and put the loop back in, and confirmed my loop is looping. My result seems to be stuck at 24543, 40910 or 8142 each time I reset. Basically giving me random numbers as best I can tell. But despite the loop looping, the numbers do not change, until I remove power from the unit, then apply power again.

Code:

---

DEFINE OSC 48

include "modedefs.bas"
include "LCD_3310.pbp"

TRISD = 0
PORTD.0 = 1  'turn on g sensor
PORTD.1 = 0  'select scale for g sensor
PORTD.2 = 0  'select scale for g sensor


TRISA = %00000111  'set porta.0, 1, and 2 as inputs
TRISB = 0
CM1CON = 7
CM2CON = 7
TRISC = 0
TRISE = 0
ADCON0 = %00000001      'turn on adc
ADCON1 = %00000010      'fosc/32 ??
'am I translating c language ADCON1=0x10 above correctly?

resx var word
x var word
y var word
z var word
adval var word

x=0
y=0
z=0
adval = 0

PORTD.0 = 1  'turn on g sensor (again)
'*************************************************
@ bsf WDTCON,ADSHR  ;set shared address SFR with WTCON<4> - is this right?
ADCON0 = %11111110  ' channel with a 0 is analog input, all others digital
@ bcf WDTCON,ADSHR
ADCON1 = %10111110  'right justified, AD=20AD, A/D clock=fosc/64
ADCON0.0 = 1        'turn on adc

ADCON0.2 = 0        'channel select bit CHS0(should already be a 0)
ADCON0.3 = 0        'Channel select bit CHS1(should already be a 0)


start:
    Pause 500      ' Wait .5 second
loop:                ADCON0.1 = 1                                        'Start Conversion
adval = 0                                  'clear result word
notdone:        pause 5
        if ADCON0.1 = 1 Then notdone        'wait for low on bit-2 of ADCON0, conversion finished

        adval.highbyte = ADRESH                        'move HIGH byte of result to adval
        adval.lowbyte = ADRESL                        'move LOW byte of result to adval
           
        'ADCON0 = %00000000              'turn off adc
                   
        'Lcdout $fe, 1                                  'Clear screen
        'Lcdout "Value: ", DEC adval        'Display the decimal value 
            x = x +1                        'test to see if loop is working
@ PrintStr 0,0, "Z= "                      ;display on Nokia 3310
@ PrintVar 24,0, _adval                    ;display result on 3310
@ PrintVar 0,1, _x                          ;show if loop is looping
        Pause 100                                      'Wait .1 second

              Goto loop                                      'Do it forever
End

---

Whoops,

I noticed that it was going to my include file, then popping up at start: which missed all my settings to the ADCON0 etc.

Sometimes I have to say it out loud (to everyone) to figure it out, with the help of some experts. I won't tell anyone how many days I was trying..........

Thanks,

Walter

You conversion clock seems a bit high @48MHz operation, and your first example in C used ANCON0, not yours.... yet...

While it's not a problem for now, one day you may need to disable some analog feature on this PIC... however, seems ANCON0 and ANCON1 are not included in PBP 2.50c, so I guess the following would be handy one day or another.

Code:

---

        '
        '      Configure ADC
        '      =============
        ANCON0  VAR BYTE EXT    ' not included in PBP2.50c
        ANCON1  VAR BYTE EXT    ' not included in PBP2.50c
       
        ANCON0 = %10011110
              '  -xx------ Not Implemented
              '  1--1111-- AN7, & AN<4:1> = Digital
              '  -------0- AN0 = Analog
             
        ANCON1 = %11111111
              '  11111111- AN<15:10> = Digital
                                   
        ADCON0 = %00000001
              '  0-------- VCFG1, Vref- 0 = AVss (1=AN2)
              '  -0------- VCFG2, Vref+ 0 = AVdd (1=AN3)
              '  --0000--- CHS<3:0>, Channel select -- 0
              '  ------0-- Go/Done, don't care for now
              '  -------1- ADON, Enable ADC
                 
        ADCON1 = %10000111
              '  1-------- ADFM, Right justified result
              '  -0------- ADCAL, Normal A/D converter operation
              '  --000---- ACQT<2:0>, A/D Aquisition time = 0 Tad
              '  -----111- ADCS<2:0>, A/D conversion clock = FRC
               
        '
        '      Hardware Aliases
        '      ================
        GoDone      var ADCON0.1 ' StartConversion = 1, Conversion done = 0
       
        '
        '      Software Variables
        '      ==================
@ADVal = ADRESL
        ADVal      VAR WORD EXT
       
Start:
        pauseus 10  ' Acquisition time       
        GoDone = 1
        While GoDone : Wend
        LCDOUT $FE, 1, "Value: ", DEC ADVal
        PAUSE 250
        GOTO START

---

EDIT: for some odd reason, ANCON0 & ANCON1 are commented in PIC18EXT.BAS, i'd sent an e-mail to Melabs, obviously they must have a reason for that.

Thanks mister_e ! I have flipped to page 299 to 302 so many times but never noticed the "D" to "N" change. Doh!

Do you think it is edited out because it is a shared address, only distinguished by the address share bit ADSHR in the WDTCON register?

Currently I have to:
@ bsf WDTCON,ADSHR 'flag address share bit
ADCON0 = %11111000 ' channels with a 0 is analog input, all others digital
@ bcf WDTCON,ADSHR
(or should I say I think? I have to....)

to set the aNcon0 register

(Despite all my mistakes, I am now getting valid conversion results, as of post 4)

Holly crap, yeah, that make sense indeed. Yet another stupidity from Microchip :eek:

So my example will need some changes...

Code:

---

        '
        '      Configure ADC
        '      =============
        ANCON0  VAR BYTE EXT    ' not included in PBP2.50c
        ANCON1  VAR BYTE EXT    ' not included in PBP2.50c
       
        WDTCON.4 = 1    ' Switch to Alternate SFR
        ANCON0 = %10011110
              '  -xx------ Not Implemented
              '  1--1111-- AN7, & AN<4:1> = Digital
              '  -------0- AN0 = Analog
             
        ANCON1 = %11111111
              '  11111111- AN<15:10> = Digital
                                   
        WDTCON.4 = 0    ' Back to Default SFR

---

or

Code:

---

        '
        '      Configure ADC
        '      =============
        WDTCON.4 = 1    ' Switch to Alternate SFR
       
        ADCON1 = %10011110  ' alternate ANCON0
              '  -xx------ Not Implemented
              '  1--1111-- AN7, & AN<4:1> = Digital
              '  -------0- AN0 = Analog
             
        ADCON0 = %11111111  ' alternate ANCON1
              '  11111111- AN<15:10> = Digital
                                   
        WDTCON.4 = 0    ' Back to Default SFR

---

By far, i prefer the first, easier to read ;)

However, yours work.. keep it like that. If it's not broken, don't fix it!

Side note... there's no real need to redefine ANCON1, ANCON0 as i did if you use ANCON1_ALT, ANCON0_ALT within your code. Those two are defined in PIC18EXT.BAS.

Having _ALT written at the right of the register name, may remember you to set/clear WDTCON.4 bit? Maybe ;)

Quote:

---

Originally Posted by mister_e

Side note... there's no real need to redefine ANCON1, ANCON0 as i did if you use ANCON1_ALT, ANCON0_ALT within your code. Those two are defined in PIC18EXT.BAS.

Having _ALT written at the right of the register name, may remember you to set/clear WDTCON.4 bit? Maybe ;)

---

Sweet! I did not see that either. May be time for glasses. And a lot cleaner than the way I was doing it, and I like the way you wrote the registry bits in the code. That would have kept me from having to divert my attention to and from tfm a lot!

Thanks for all the help.

Walter

To me, comments are really important. So, on the long run... coding like that

Code:

---

        ADCON0 = %00000001
              '  0-------- VCFG1, Vref- 0 = AVss (1=AN2)
              '  -0------- VCFG2, Vref+ 0 = AVdd (1=AN3)
              '  --0000--- CHS<3:0>, Channel select -- 0
              '  ------0-- Go/Done, don't care for now
              '  -------1- ADON, Enable ADC

---

May indeed avoid to open the datasheet all the time, one thing is sure, it's easier to modify/understand later.