Microchip Technology XC8 Standard Compiler (Workstation) SW006021-1 SW006021-1 User Manual

 2012 Microchip Technology Inc.

DS52053B-page 329

#include <xc.h>

 

unsigned int device_id_read(void);

This function returns the device ID code that is factory-programmed into the chip. This 
code can be used to identify the device and its revision number.

#include <xc.h>

void 

main (void)

{

    unsigned int   id_value;

    unsigned int   device_code;

    unsigned char revision_no; 

    id_value = device_id_read();

        /* lower 5 bits represent revision number

         * upper 11 bits identify device */

    device_code = (id_value >> 5);

    revision_no = (unsigned char)(id_value & 0x1F);

}

flash_read()

, config_read()

device_id_read()

 returns the 16-Bit factory-programmed device id code used to 

identify the device type and its revision number.

The 

device_id_read()

 is applicable only to those devices which are capable of 

reading their own program memory.

#include <xc.h>

 

void ei (void)

void di (void)

The 

di()

 and 

ei()

 routines disable and re-enable interrupts respectively. These are 

implemented as macros. The example shows the use of 

ei()

 and 

di()

 around access 

to a long variable that is modified during an interrupt. If this was not done, it would be 
possible to return an incorrect value, if the interrupt occurred between accesses to 
successive words of the count value.

The ei() macro should never be called in an interrupt function, and there is no need 
to call di() in an interrupt function.