Here is the data_write function I'm looking at. I've been told that this method (from the textbook) is not good and I should be using the C method (that is currently commented out). When the Cbits method is used, any arguments after the _asm/_endasm the compiler doesn't recognize the bit names (they don't turn green).

If I use only the assembly method, I get a string of errors [1111] about the undefined label (WR, GIE, EECON1, etc.) inside this function. Do I have to somehow re-define the ADC.h inside the function? Basically, all of the register names (EECON1, etc) and bit names (WR, WREN, etc.) are not recognized inside the function "data_write" if they are inside the assembly tags (_asm/_endasm). If I use the Cbits.BIT method, I get a generic syntax error and the bits following _endasm are not identified (turn green).

#include <stdio.h>
#include <stdlib.h>
#include <p18f452.h>
#include <delays.h>
#include <adc.h>

int result;                         // used in ADC result handling
int write_point=0x64;               // used in data_write function. initial=d100

void data_write (int write_point, int result);   // declare prototype

void main(void)  // <==should this be 'int main (void)' b/c i'm passing result to another function ?
    while (1) {
    // sensor 1 configured to port AN0
                            //configures ADC for port AN0 = sensor 1 input
            ConvertADC();               // initiate conversion of sensor1 @ AN0
            while(BusyADC());           // waiting to complete conversion
            result=ReadADC();           // read the result of sensor1 @ AN0
            data_write(result, write_point);

void data_write (int write_point, int result) {

/*        EECON1bits.EEPGD = 0       // points to data memory
         EECON1bits.CFGS = 0        // access data eeprom
         EECON1bits.WREN = 1        // enable write to data eeprom
         INTCONbits.GIE=0           // disable interrupt
** if I substitute this method of bit control, this 2nd portion belongs after 
 * the asm arguments, but the bits (WR, GIE, WREN) will not be identified
 * either an I get a syntax error. (of course commenting out the bcf/bsf statements)
        EECON1bits.WR = 1       // enable bit to start the write operation
        INTCONbits.GIE = 1      // re-enable interrupt
        EECON1bits.WREN = 0    // restores the write command to =disabled */

 movlw  write_point        // starting data memory address = data_adr
 movwf  EEADR,A
 movlw  result              // gets data stored in "result" variable
 movwf  EEDATA,A            // places data into data memory holder
 bcf    EECON1,EEPGD,A      // points to data memory
 bcf    EECON1,CFGS,A       // access data eeprom
 bsf    EECON1,WREN,A       // enable write to data EEPROM
 bcf    INTCON,GIE,A         // disable interrupt
 movlw  0x55                // start flash erase sequence
 movwf  EECON2,A
 movlw  0xAA
 movwf  EECON2,A            // end flash erase sequence
 bsf    EECONN1,WR,A        // enable bit to start the write operation
 bsf    INTCON,GIE,A        // re-enable interrupt
 bcf    EECON1,WREN         // restores the write command to =disabled

 write_point = write_point+2;  // increment address by 2
 if (write_point >= 0xC6)      // if address >= d'198
     write_point = 0x64;       // resets starting point to d'100


For the commented out C part, you don't appear to have have any ending semicolons (e.g. first line should be EECON1bits.EEPGD = 0;) , so the compiler certainly won't like that.

For the inline assembly, IIRC the register names hould b e usable, but I think you have to specify operands fully (e.g. instead of movwf EECON2,A you do movwf EECON2,0)
It's possible the bit names must be specified by number instead of name too, for example instead of bcf EECON1,EEPGD,A you do bcf EECON1, 7, 0 (EEPGD is bit 7 of EECON1) The A at the end is not right anyway, this should be 1 or 0 (or W or F in MPASM)
It's been a while since I used the inline assembly for anything like this so memory is fuzzy, but try it and let us know how it goes.

  • \$\begingroup\$ Yay! dropping those ",A" to ",0" did the trick! Thanks @Oli !!! \$\endgroup\$
    – Mark
    Oct 3 '12 at 2:14

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