Conditional compiling

Hi John7,

I assume your blink_led routine is the same for both PCB version and only the 'LED pin' differs (--> different hardware layer).

I would recommend using another type of conditional compiling; have a look at the example below:
/*-----------------------------------------------------------------------------
// Compiler switches
// used as:
//            #ifdef  PCB_REV1
//             ...  ; additional code lines used with PCB Revison 1 only
//            #endif
// ONLY USE ONE COMPILER SWITCH!
//---------------------------------------------------------------------------*/
#define PCB_REV1                           // code lines used with PCB Revison 1
//#define PCB_REV2                           // code lines used with PCB Revison 2

// defines for hardware connection
#ifdef PCB_REV1
#define LED_1_ON      P1OUT |= BIT4;      // output HIGH --> switch on
#define LED_1_OFF     P1OUT &= ~BIT4;     // output LOW --> switch off
                                          // LED_1 is connected to P1.4
#define LED_1_TOGGLE  P1OUT ^= BIT4;      // toggles P1.4
#endif

#ifdef PCBREV2
#define LED_1_ON      P3OUT |= BIT6;      // output HIGH --> switch on
#define LED_1_OFF     P3OUT &= ~BIT6;     // output LOW --> switch off
                                          // LED_1 is connected to P3.6
#define LED_1_TOGGLE  P3OUT ^= BIT6;      // toggles P3.6
#endif

Be shure to have the I/O pins configured accordingly, i.e.:

// configure I/Os
#ifdef PCB_REV1                         
P1DIR |= BIT4;                          // P1.4 is switched to output mode, 1                  
LED_1_OFF;                              // output LOW --> LED_1 off
#endif

#ifdef PCB_REV2                         
P3DIR |= BIT6;                          // P3.6 is switched to output mode, 1                  
LED_1_OFF;                              // output LOW --> LED_1 off
#endif

This example shows that I have one #define (i.e. LED_1_ON) which could be connected to two different pins (P1.4 or P3.6).

During my application I only refer to LED_1_ON, so I don't need to care about the context I'm in.
I.e.:

void blink_led
{
    LED_1_ON;  // output HIGH --> switch on LED
    __delay_cycles(35000); // make some delay
    LED_1_OFF;  // output LOW --> switch off LED
    __delay_cycles(35000); // make some delay
}

Rgds
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