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Guest
Guest
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| write_eeprom w/16F877 |
 Posted: Mon Jun 14, 2004 11:48 pm |
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Hi -
I wish to write constants to the EEPROM of the 16F877, but not use the #ROM directive if I can help it. I want to use the "write_eeprom" command (PCM 3.185). However, whenever I use the write_eeprom command in my main() function [for example: write_eeprom(1, 11) to test the command], I get the error "A numeric expression must appear here" on the line following the write_eeprom command. I have turned off all the relevant fuses I believe.
For what its worth, testing the read_eeprom command gives me the same (or similar) error.
Do I need to issue other setup commands to "enable" use of the eeprom? This should be easier than it is getting to be.......
Thank you for comments. |
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Haplo
Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia
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| Posted: Tue Jun 15, 2004 4:16 am |
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| There are no special setup steps needed to activate the EEPROM. Post your code so we can take a look at it. |
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rnielsen
Joined: 23 Sep 2003
Posts: 852
Location: Utah
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| Posted: Tue Jun 15, 2004 8:36 am |
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This is what I use to initialize a set of variables. If a button (input) is pressed upon powerup, I have certain default values written to the onboard eeprom.
| Code: |
if(!input(PIN_B2)) // initialize the onboard eeprom to default values
{ // this needs to be done after the MCU is first programmed
write_eeprom(0x00, 0x50);
write_eeprom(0x01, 0x06);
write_eeprom(0x02, 0x05);
write_eeprom(0x03, 0x1E);
write_eeprom(0x04, 0x03);
write_eeprom(0x05, 0xFF);
write_eeprom(0x06, 0x00);
write_eeprom(0x07, 0x05);
write_eeprom(0x08, 0x00);
write_eeprom(0x09, 0x00);
write_eeprom(0x0A, 0x00);
write_eeprom(0x0B, 0x00);
write_eeprom(0x0C, 0x00);
write_eeprom(0x0D, 0x00);
write_eeprom(0x0E, 0x00);
write_eeprom(0x0F, 0x00);
}// end of if(!input)
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Simple as that. Just make sure that you are not trying to write a value above the physical address of the eeprom.
I just thought of this too, the error is most likely just above where the compiler says the error is. It has a tendency to do that. Try looking a few lines 'UP' the code to see if you messed up something there.
Ronald |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Jun 15, 2004 12:19 pm |
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| Quote: | I want to use the "write_eeprom" command (PCM 3.185). However,
whenever I use the write_eeprom command in my main() function [for
example: write_eeprom(1, 11) to test the command], I get the error
"A numeric expression must appear here" on the line following the
write_eeprom command. |
I installed PCM vs. 3.185 and compiled this test program.
It compiled OK, with no errors. I suggest that you
re-install the compiler (just to be sure), and then try this program.
#include <16F877.h>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 4000000)
//=========================================
void main()
{
write_eeprom(1, 11);
while(1);
} |
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Guest
Guest
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| write_eeprom |
| Posted: Tue Jun 15, 2004 2:18 pm |
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PCM (and others):
Thanks.
Yes, I also wrote a really simple program like you did and I had no problems. The compiler didn't squawk and my data was in the EEPROM locations I specified. This is how I anticipated the command would work.
I don't have the code here with me now that bombed out when it encountered the "write_eeprom" command. That program has lots of defines and other stuff in it. However, when I get home I'll try again to recreate the problem (shouldn't be a problem....) and post it.
Thanks again! |
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