PicForum

I tried writing and reading the EEPROM on my PIC18F46K80, and it always reads back as zero.
I'm writing in C and using XC8 functions: eeprom_write() and eeprom_read(). I also tried
using the __EEPROM_DATA macro.

What am I missing?
Thanks!



Here's my code:

Code: Select all


#ifndef __18F46K80
#define __18F46K80
#warning "Code is targeted for PIC18F46K80"
#endif

#pragma config RETEN = OFF      // VREG Sleep Enable bit (Ultra low-power regulator is Disabled (Controlled by REGSLP bit))
#pragma config INTOSCSEL = HIGH // LF-INTOSC Low-power Enable bit (LF-INTOSC in High-power mode during Sleep)
#pragma config SOSCSEL = DIG    // SOSC Power Selection and mode Configuration bits (Digital (SCLKI) mode)
#pragma config XINST = OFF      // Extended Instruction Set (Disabled)
#pragma config FOSC = HS1       // Oscillator (Internal RC oscillator, CLKOUT function on OSC2)
#pragma config PLLCFG = OFF     // PLL x4 Enable bit (Disabled)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor (Disabled)
#pragma config IESO = OFF       // Internal External Oscillator Switch Over Mode (Disabled)
#pragma config PWRTEN = OFF     // Power Up Timer (Disabled)
#pragma config BOREN = OFF      // Brown Out Detect (Disabled in hardware, SBOREN disabled)
#pragma config BORV = 3         // Brown-out Reset Voltage bits (1.8V)
#pragma config BORPWR = ZPBORMV // BORMV Power level (ZPBORMV instead of BORMV is selected)
#pragma config WDTEN = OFF      // Watchdog Timer disabled
#pragma config WDTPS = 1024     // Watchdog Postscaler (1:1024), so every 4.096 seconds
#pragma config CANMX = PORTB    // ECAN Mux bit (ECAN TX and RX pins are located on RB2 and RB3, respectively)
#pragma config MSSPMSK = MSK7   // MSSP address masking (7 Bit address masking mode)
#pragma config MCLRE = ON       // Master Clear Enable (MCLR Enabled, RE3 Disabled)
#pragma config STVREN = ON      // Stack Overflow Reset (Enabled)
#pragma config BBSIZ = BB2K     // Boot Block Size (2K word Boot Block size)
#pragma config CP0 = OFF        // Code Protect 00800-03FFF (Disabled)
#pragma config CP1 = OFF        // Code Protect 04000-07FFF (Disabled)
#pragma config CP2 = OFF        // Code Protect 08000-0BFFF (Disabled)
#pragma config CP3 = OFF        // Code Protect 0C000-0FFFF (Disabled)
#pragma config CPB = OFF        // Code Protect Boot (Disabled)
#pragma config CPD = OFF        // Data EE Read Protect (Disabled)
#pragma config WRT0 = OFF       // Table Write Protect 00800-03FFF (Disabled)
#pragma config WRT1 = OFF       // Table Write Protect 04000-07FFF (Disabled)
#pragma config WRT2 = OFF       // Table Write Protect 08000-0BFFF (Disabled)
#pragma config WRT3 = OFF       // Table Write Protect 0C000-0FFFF (Disabled)
#pragma config WRTC = OFF       // Config. Write Protect (Disabled)
#pragma config WRTB = OFF       // Table Write Protect Boot (Disabled)
#pragma config WRTD = OFF       // Data EE Write Protect (Disabled)
#pragma config EBTR0 = OFF      // Table Read Protect 00800-03FFF (Disabled)
#pragma config EBTR1 = OFF      // Table Read Protect 04000-07FFF (Disabled)
#pragma config EBTR2 = OFF      // Table Read Protect 08000-0BFFF (Disabled)
#pragma config EBTR3 = OFF      // Table Read Protect 0C000-0FFFF (Disabled)
#pragma config EBTRB = OFF      // Table Read Protect Boot (Disabled)


#include <pic18.h>     // Should bring in p18f46k80.h too
#include <stdio.h>     // For printf

__EEPROM_DATA(0x11,0x22,0x33,0x44,0x55,0x66,0x77,0x88);

void main()
{
   TRISA = TRISB = TRISC = TRISE = RDPU = 0;   // Benign
   TMR0 = 0, T0CON = 0x80;                     // 1MHz  (Fosc/4 (=2MHz), prescale 2:1), start running

   printf("Initial read of EEPROM[0-7]: %u %u %u %u %u %u %u %u\r\n",
      eeprom_read(0), eeprom_read(1), eeprom_read(2), eeprom_read(3),
      eeprom_read(4), eeprom_read(5), eeprom_read(6), eeprom_read(7));
   
   eeprom_write(27, 42);
   while(WR)
      continue;
   printf("Wrote EEPROM[27] non-zero, got %u\r\n", eeprom_read(27));

   eeprom_write(28, 0xff);
   while(WR)
      continue;
   printf("Wrote EEPROM[28] non-zero, got %u\r\n", eeprom_read(28));
   
   while(1)
      continue;
}

void putch(char c)   // For printf...bit-bang serial I/O
{
unsigned int shifter, next_bit;
char i;
 
   shifter = c;
   shifter <<= 1;                        // Move left, leaving START=0 bit
   shifter |= 0x600;                     // OR in two STOP=1 bits
   while (TMR0 > 0xf800)                 // Spin if we're within 2 ms of TMR0 wrapping
      continue;
   next_bit = TMR0 + 104;

   for (i=0; i<11; i++)
      {
      LATBbits.LATB5 = (0x1 & shifter);  // Non-inverted output
      shifter >>= 1;                     // Right shifter (start, then LSB->MSB, then stop, stop)
      while (TMR0 < next_bit)            // Spin until time for next bit
         continue;
      next_bit += 104;                   // 9600 baud = 104 usec per bit
      }
   LATBbits.LATB5 = 1;                   // Back to idle
}


...and here's what those printfs output:

Initial read of EEPROM[0-7]: 0 0 0 0 0 0 0 0
Wrote EEPROM[27] non-zero, got 0
Wrote EEPROM[28] non-zero, got 0

I don't know how those eeprom_* functions are implemented, but make sure you're clearing the EEPGD bit in EECON1. And don't "#define __18F46K80" since that could interfere with the compiler's internals.

Which version of XC8 are you using?
The latest versions don't come with the PLIB library. If you don't install it, those functions do nothing.