error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before '{' token

[anju1401]

Hi
I am using WINAVR compiler for ATMEGA32. While compiling c progam , I am getting the error
error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribu te__’ before '{' token
before evrey function.

code:

#include <avr\io.h>
 
#include <stdio.h>
 
#include <avr\delay.h>
 
#include <math.h>
 
void initialize(void);
 
char val;
 
 
 
// current measurement state
 
enum {PULSE, GSR, BREATH} measure, nextmeasure;
 
 
 
// current signal voltages
 
char pulseV = 0;
 
char gsrV = 0;
 
char breathV = 0;
 
 
 
// enter every 100Hz
 
interrupt(TIM0_COM) void getAD(void)
 
{
 
    // sample A/D and store
 
    val = ADCH;
 
    // start a/d converter
 
    switch(measure)
 
    {
 
        case PULSE:
 
            pulseV = val << 1;
 
            nextmeasure = GSR;
 
            break;
 
        case GSR:
 
            gsrV = val;
 
            nextmeasure = BREATH;
 
            break;
 
        case BREATH:
 
            breathV = val;
 
            nextmeasure = PULSE;
 
            break;
 
    }
 
 
 
    switch(nextmeasure)
 
    {
 
        case PULSE:  ADMUX = 0b01100001; break;
 
        case GSR:    ADMUX = 0b01100010; break;
 
        case BREATH: ADMUX = 0b01100011; break;
 
    }
 
    measure = nextmeasure;
 
 
 
    ADCSR.6 = 1;
 
}
 
 
 
// send signals to MATLAB for drawing
 
void transmit()
 
{
 
    printf("%d ", (int)pulseV);
 
    printf("%d ", (int)gsrV);
 
    printf("%d ", (int)breathV);
 
    printf("\r");    // end packet
 
    PORTD.7 = ~PORTD.7;
 
}
 
 
 
// read A/D converter and communicate with MATLAB
 
void main(void)
 
{
 
    char inchar;
 
 
 
    initialize();
 
 
 
    while(1)
 
    {
 
        // when signaled by MATLAB, return current values
 
        if (UCSRA.7)
 
        {
 
            inchar = UDR;
 
            if (inchar=='s') {
 
                transmit();
 
            }
 
        }
 
    }
 
}
 
 
 
// setup
 
void initialize(void)
 
{
 
    // comm indicator LED
 
    DDRD.7 = 1;
 
    PORTD.7 = 0;
 
 
 
    // serial RS-232  setup for debugging using printf, etc.
 
    UCSRB = 0x18;
 
    UBRRL = 103;
 
 
 
    // set up timer0 to sample a/d at about 100Hz
 
    TCCR0 = 0b00000101;
 
    TIMSK = 0b00000010;
 
    OCR0 = 156;
 
 
 
    // set up a/d for external Vref, channel 0
 
    // channel zero / left adj / AVcc Reference
 
    // A1=PULSE, A2=GSR, A3=BREATH
 
    ADMUX = 0b01100001;
 
 
 
    // enable ADC and set prescaler to 1/128*16MHz=125kHz
 
    // and clear interupt enable
 
    // and start a conversion
 
    ADCSR = 0b11000111;
 
 
 
    measure = PULSE;
 
    _sei();
 
}

[Banfa]

I can't see anything particularly wrong with this code, allowing for AVR micro-controller extensions, are these the only errors you are getting?

If not please post all your errors.

[anju1401]

I am getting the following errors:

c:/winavr-20090313/lib/gcc/../../avr/include/avr\delay.h:36: 2: warning: #warning "This file has been moved to <util/delay.h>."
try.c:33: warning: return type defaults to 'int'
try.c:33: warning: function declaration isn't a prototype
try.c: In function 'interrupt':
try.c:35: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token
try.c:99: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token
try.c:121: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token
try.c:159: error: expected '=', ',', ';', 'asm' or '__attribute__' before '{' token
try.c:213: warning: type of 'TIM0_COM' defaults to 'int'
try.c:213: error: expected '{' at end of input

[Banfa]

SOunds like a problem with

interrupt(TIM0_ COM) void getAD(void)

I would start my removing interrupt(TIM0_ COM) from this line and seeing it you can get it to compile. This wont produce a runable program but will make sure you have your C syntax correct.

The interrupt(TIM0_ COM) is clearly an extension presumably to generate interrupt routines for the AVR micro-controler. That means it is an extension and not standard C. You will have to careful check your compiler documentation and make sure you are using the extension correctly including

• Setting any compiler switches required by the extension.
• Including any headers required by the extension.

Above all make sure you read your compiler documentation on how to define interrupt handlers.

[anju1401]

Thanks.I have not included the file "avr\interrupt. h". But after adding this file I am getting the following errors :

try.c:91: error: expected ';' before numeric constant
try.c:111: error: expected ';' before numeric constant
try.c:137: error: expected ';' before numeric constant
try.c:165: error: expected ';' before numeric constant
try.c:167: error: expected ';' before numeric constant

Can't I access just one bit of any register?

[newb16]

You can, but the source code you got is for some other compiler for avr - iar, icc or whatever. avr-gcc doesn't support "regname.N" bit addressing, use instead
regname |= 1<<N to set bit N.

[Banfa]

Well no, or may be yes, but not like that. There is no way that this syntax

ADCSR.6 = 1;

could be valid standard C and it is an unlikely extension.

The way to access a bit in the register (assuming 8 bit registers) is this

    /* To read */
    unsigned char reg = ADCSR;
    unsigned char bit;
 
    bit = (reg >> N) & 1;
 
    /* To Write */
    ADCSR |= (1 << N);
 

Where in both cases N is the bit number to access in the range 0 - 7.

Accessing bits in registers must be done carefully. It is easy to accidentally destroy data. For instance (and I take this from a real life error) imagine an 8 bit register that has 4 data bits and a data ready bit that indicates the data bits are valid. When you read the register the data ready bit is cleared and the hardware starts acquiring another value (as in an ADC).

I saw (and corrected an implementation) that did this

    int data;
    if (REGISTER & DATA_READY_BIT) /* Test data ready bit */
    {
        data = REGISTER & DATA_BITS_MASK;
    }
 

The problem is that the register is actually read twice. The first time to test the data ready bit, the second time to read the data if it is set. That sounds fine but remember my description above. When you read the register the data ready bit is cleared and the hardware starts acquiring another value invalidating the data bits. This method effectively invalidates the data bits testing the data ready bit, you can never read a proper value form the register.

It needs to be written like this

    int data;
    unsigned char reg;
 
    reg = REGISTER;
 
    if (reg & DATA_READY_BIT) /* Test data ready bit */
    {
        data = reg & DATA_BITS_MASK;
    }
 

This only reads the register once, then if the data ready bit is set it uses the value read at the same time as the data ready bit.


The point is that when you access (for read or write) hardware registers directly you have to be aware of any side effects that access may have on that or other registers.

You will need to know and understand the bitwise and shift operators.

[anju1401]

Thanks a lot for your help. Can you also tell me how to go about correcting it :
PORTD.7 = ~PORTD.7; ?

[Banfa]

You are trying to toggle bit 7, yes?

You need to use xor ^ operator.

Either read the register into a variable perform the xor and write out the new value or xor directly with the register ^=.

In the rhs operand set the bits you want to toggle to 1and bits you want to leave along to 0.

PORTD ^= 0x80;

[anju1401]

Yes , I was trying to toggle that particular bit.
Thanks a lot for your help.