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VanHauser
Joined: 03 Oct 2005
Posts: 88
Location: Ploiesti, Romania
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| 18F452: Strange code protection problem |
 Posted: Sun Jan 08, 2006 5:09 am |
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I enabled code protection for a 18F452 like this:
| Code: | | #fuses HS, PROTECT,NOOSCSEN,BROWNOUT,BORV45,WDT,WDT128,PUT,NOSTVREN,NODEBUG,NOLVP,WRT,NOCPB,WRTB,WRTC,NOCPD,NOWRTD,NOEBTR,NOEBTRB |
You cand see that the boot block is unprotected (NOCPB), so I can read it back from the PIC, but nothing more. The problem appears when I enable CPB, the firmware cannot write to the internal EEPROM anymore, though it's not protected at all! Is the PIC confusing EEPROM addresses with program memory addresses or am I doing something wrong? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sun Jan 08, 2006 3:28 pm |
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| Quote: | | the firmware cannot write to the internal EEPROM anymore, |
I made a test program using your #fuses statement. The only thing I
changed was the oscillator setting: HS to XT. I compiled it with PCH
vs. 3.241, and it works OK. It can write and read from internal eeprom.
Here is output of the program given below:
| Quote: |
Wrote 00, Read 00
Wrote 01, Read 01
Wrote 02, Read 02
Wrote 03, Read 03
Wrote 04, Read 04
Wrote 05, Read 05
Wrote 06, Read 06
Wrote 07, Read 07
Wrote 08, Read 08
Wrote 09, Read 09 |
| Code: | #include <18F452.h>
#fuses XT, PROTECT,NOOSCSEN,BROWNOUT,BORV45,WDT,WDT128,PUT,NOSTVREN,NODEBUG,NOLVP,WRT,NOCPB,WRTB,WRTC,NOCPD,NOWRTD,NOEBTR,NOEBTRB
#use delay(clock=4000000, restart_wdt)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS, restart_wdt)
//=============================
void main()
{
int8 i;
int8 c;
for(i = 0; i < 10; i++)
{
write_eeprom(0, i);
c = read_eeprom(0);
printf("Wrote %X, Read %X\n\r", i , c);
restart_wdt();
}
while(1)
{
restart_wdt();
}
} |
Here are the fuse settings shown at the end of the .LST file.
Do they match the ones shown in your .LST file ?
| Code: | Configuration Fuses:
Word 1: 2100 XT NOOSCSEN
Word 2: 0F02 BROWNOUT WDT128 WDT BORV45 PUT
Word 3: 0100 CCP2C1
Word 4: 0080 NOSTVREN NODEBUG NOLVP
Word 5: C000 PROTECT NOCPD NOCPB
Word 6: 8000 WRT NOWRTD WRTB WRTC
Word 7: 400F NOEBTR NOEBTRB |
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VanHauser
Joined: 03 Oct 2005
Posts: 88
Location: Ploiesti, Romania
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| Posted: Fri Jan 13, 2006 8:20 am |
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It works for me too with the fuses you used. Try it with CPB instead of NOCPB, mine fails if I do so  |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Jan 13, 2006 4:50 pm |
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I don't have my 18F452 board with me at the moment, so I tested it
with a 18F458 board. This is with PCH vs. 3.241. It still worked.
I can test it later with a 18F452, but the 18F458 is similar.
Have you tried the test program shown below ?
Results:
| Quote: |
Wrote 00, Read 00
Wrote 01, Read 01
Wrote 02, Read 02
Wrote 03, Read 03
Wrote 04, Read 04
Wrote 05, Read 05
Wrote 06, Read 06
Wrote 07, Read 07
Wrote 08, Read 08
Wrote 09, Read 09 |
I changed the fuse to CPB as you said:
| Quote: | #include <18F458.h>
#fuses XT, PROTECT,NOOSCSEN,BROWNOUT,BORV45,WDT,WDT128,PUT,NOSTVREN,NODEBUG,NOLVP,WRT,CPB,WRTB,WRTC,NOCPD,NOWRTD,NOEBTR,NOEBTRB
#use delay(clock=4000000, restart_wdt)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS, restart_wdt)
//=============================
void main()
{
int8 i;
int8 c;
for(i = 0; i < 10; i++)
{
write_eeprom(0, i);
c = read_eeprom(0);
printf("Wrote %X, Read %X\n\r", i , c);
restart_wdt();
}
while(1)
{
restart_wdt();
}
} |
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VanHauser
Joined: 03 Oct 2005
Posts: 88
Location: Ploiesti, Romania
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| Posted: Sat Jan 14, 2006 7:17 am |
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My routine that writes to the internal EEPROM also reads back for verification. It makes 3 write/read attempts. write_eeprom() and read_eeprom() work both, BUT what is read back is not the same with what is was written! This happens just by enabling CPB.
Here is the routine:
| Code: | #separate
void save_config() {
int8 addr;
signed int8 i;
signed int8 attempt;
int8 *ptr;
int1 failed;
config.markAA = 0xAA;
config.mark55 = 0x55;
// Make the CRC, excluding the last two bytes assigned to it
config.crc = generate_crc((int8 *)&config, sizeof(config)-2);
attempt=0;
do {
// Write
addr = 0;
ptr = (int8 *) &config;
for (i=0; i<sizeof(config); i++) {
write_eeprom(addr, *ptr);
addr++;
ptr++;
}
// Verify
addr = 0;
ptr = (int8 *) &config;
failed = FALSE;
for (i=0; i<sizeof(config); i++) {
if ((*ptr) != read_eeprom(addr)) {
failed = TRUE;
break;
}
addr++;
ptr++;
}
if (!failed) return;
attempt++;
} while (failed && (attempt<WRITE_ATTEMPTS));
// HALT, every write/verify attempt failed
write_fault_code = 'C';
goto_address(ADDR_HALT);
} |
PCM Programmer, I am sorry but I can't test your code for the moment, I don't have any boards. The project the routine makes part of is in stable mode, but I want to enable full protection. I forgot to mention that the crystal it uses is 8 MHz. |
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