In C, the switch{} case values must be constant expressions. They are
evaluated at comile time. You cannot have an X in a case. You'll have to
implement your condition another way.

Jon

> -----Original Message-----
> From: andre abelian [mailto:engelec@EARTHLINK.NET]
> Sent: 25 September 2003 23:22
> To: PICLIST@MITVMA.MIT.EDU
> Subject: [EE:] need help on c code
>
>
> Hi to all engineers,
>
> Some thing I can't figure out any help will appreciate.
> I have timer0 on high priority ISR and adc on low priority. I
> need to add adc result in timer0 ISR example. in timer0  I
> have case(28+0) I needed to be case(28+x) any time I change 0
> to x I get error massage
>
> Error[000] power_inveter.c 104 : constant expression required
>
> x is adc  result register I need to either add or subtract
> when I do this #define unsigned int x=5; it works but it is
> constant number is not going to work for me I need that
> number to come from ADC. My adc works when I check x register
> I see numbers are chenging
>
> Andre
>
> Here is the code
>
> void interrupt HI_ISR(void)
> {
>             if((TMR0IF)&&(TMR0IE))
>             {
>     CLRWDT();                                 // clear WDT
>     TMR0IF=0;                                 // clear interrupt flag
>     TMR0L=119;                                // timer0
> should get 46,25
> us
>     switch (count)                            // check count register
> 0-360
>          {
>     case (0):     topgd=0;                    // 0 degree
>                   bottomgd=1;                 //
>                   topga=0;                    //
>                   bottomga=1;                 //
>                   count++; break;             //
>     case (28+x):  bottomga=0; count++; break; //
>     case (30+0):  topgd=0;                    //
>                   bottomgd=1;                 //
>                   topga=1;                    //
>                   count++; break;             //
>     case (152-0): bottomgd=0; count++; break; //
>     case (154-0): topgd=1;                    //
>                   topga=1;                    //
>                   bottomga=0;                 //
>                   count++; break;             //
>     case (206+0): topga=0; count++; break;    //
>     case (208+0): topgd=1;                    //
>                   bottomgd=0;                 //
>                   bottomga=1;                 //
>                   count++; break;             //
>     case (330-0): topgd=0; count++; break;    //
>     case (332-0): bottomgd=1;                 //
>                   bottomga=1;                 //
>                   topga=0;                    //
>                   count++; break;             //
>     case (360):   topgd=0;                    //
>                   bottomgd=1;                 //
>                   topga=0;                    //
>                   bottomga=1;                 //
>                   count=0;                    //
>     default :     count++; break;             //
>          }
>     }
> }
>
> void interrupt low_priority LOW_ISR(void)
> //static void interrupt isr(void)
> {
> //  unsigned int x;
>     if((ADIF)&&(ADIE))
>     {
>     while(GODONE)continue;
>     ADIF=0;          // clear A/D flag
>     x=(ADRESH*50/255);
> //  PORTB=ADRESH;
>     GODONE=1;   // start new conversion
>     DelayUs(10);
>     adtest^=0x01;      // togle led on/off
> }
>
>
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