SW500007 Microchip Technology, SW500007 Datasheet - Page 246

• Manufacturer Part Number: SW500007
• Description: PICC-18 PRO
• Manufacturer: Microchip Technology
• Type: Compilerr
• Series: PIC18r

Specifications of SW500007

• Supported Families: PIC18
• Core Architecture: PIC
• Software Edition: Professional
• Kit Contents: Software And Docs
• Mcu Supported Families: PIC18
• Tool Function: Compiler
• Tool Type: Compiler
• Lead Free Status / RoHS Status: Not applicable / RoHS Compliant
• For Use With/related Products: PIC18 Series
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 015P; 778-1002; 778-1002

PERSIST_CHECK, PERSIST_VALIDATE
Synopsis
Description
The persist_check() function is used with non-volatile RAM variables, declared with the persistent
qualifier. It tests the nvram area, using a magic number stored in a hidden variable by a previous call
to persist_validate() and a checksum also calculated by persist_validate(). If the magic number and
checksum are correct, it returns true (non-zero). If either are incorrect, it returns zero. In this case it
will optionally zero out and re-validate the non-volatile RAM area (by calling persist_validate()).
This is done if the flag argument is true.
set up the magic number and recalculate the checksum.
Example
232
The persist_validate() routine should be called after each change to a persistent variable. It will
#include <sys.h>
int persist_check (int flag)
void persist_validate (void)
#include <sys.h>
#include <stdio.h>
persistent long reset_count;
void
main (void)
{
if(!persist_check(1))
else
reset_count++;
persist_validate();
for(;;)
printf("Reset count invalid - zeroed\n");
printf("Reset number %ld\n", reset_count);
continue;
/* sleep until next reset */
/* update count */
/* and checksum */
Library Functions