IFDEF Example

IFDEF Example

Directives highlighted in this example are:

• #define

ifdef

else

endif

Program Functional Description

This program uses the control directive #define, along with the ifdef, else and endif directives to seletively assemble code for use with either an emulator or an acutal part. The list directives title and list p= are used to set the title and processor and display this information in the list file. The control directive #include is used to include the standard header file for the selected device.

Commented Code Listing

title "PICmicro with Flash EE data memory Interface"

list p=12ce518

#include <p12ce518.inc>

;#define EMULATED

.

.

.

; Emulation Requires:

; MPLAB-ICE

; PCM16XA0 processor module

; DVA12XP80 Device Adapter

; Define EMULATOR at the top of this file

; (#define EMULATOR)

; This will set the I2C_PORT, SDA and SCL lines

; to communicate over Port A, pins 0 and 1. It

; also assembles in the necessary TRIS

; instructions to allow reading from the SDA line.

;

; To convert the code for the actual part, simply comment

; out the #define EMULATOR line and reassemble.

.

.

.

#ifdef EMULATED

I2C_PORT EQU 5 ; Port A control register,

; used for I2C

SCL EQU 01H ; EEPROM Clock, SCL (I/O bit 7)

SDA EQU 00H ; EEPROM Data, SDA (I/O bit 6)

#else

I2C_PORT EQU GPIO ; Port B control register,

; used for I2C

SCL EQU 07H ; EEPROM Clock, SCL (I/O bit 7)

SDA EQU 06H ; EEPROM Data, SDA (I/O bit 6)

#endif

.

.

.

START_BIT

BCF I2C_PORT,SDA ; Start bit, SDA and SCL

; preset to "1"