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Vefa
Joined: 13 Feb 2007
Posts: 9
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| write_ext_eeprom |
 Posted: Tue Feb 20, 2007 4:03 pm |
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Hi Everyone,
Does anyone have any idea why the following simple code would not work?
| Code: | #include <18F8722>
#include <24515.c>
#include <stdlib.h>
#include <math.h>
#fuses HS,NOWDT,NOPROTECT,PUT,NOLVP
#use delay(clock=10000000)
#use rs232(baud=2400, xmit=PIN_A4, rcv=PIN_A5, stream=PC, ERRORS)
#define LED PIN_F0
void main(void)
{
short int c=5;
long address=10;
while(1)
{
fputc('a', PC);
delay_ms(50);
init_ext_eeprom();
WRITE_EXT_EEPROM(address, c);
delay_ms(50);
fputc('*', PC);
}
} // end of main
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It prints an "a" and waits there.
Thanks |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Feb 20, 2007 4:09 pm |
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Follow standard debugging procedures. Comment out lines of code
until you find out which line is causing the problem. |
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Vefa
Joined: 13 Feb 2007
Posts: 9
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| Posted: Tue Feb 20, 2007 4:30 pm |
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| write_ext_eeprom line does not work. I checked my hardware. Am I missing something in the code? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Feb 20, 2007 4:49 pm |
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Do you have pull-up resistors on the each of the SDA and SCL lines ?
You need them for i2c. You can use 4.7K.
Also, I noticed something else about your program.
Did you know that in CCS, a 'short' is a 1-bit variable ?
Download the CCS manual and look at page 23 (page 33 in the Acrobat
reader). It shows a table with the sizes of the data types.
http://www.ccsinfo.com/downloads/ccs_c_manual.pdf |
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Vefa
Joined: 13 Feb 2007
Posts: 9
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| Posted: Tue Feb 20, 2007 8:06 pm |
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Thanks PCM programmer. I have the pull ups. I used int instead of short int. Thanks for the manual as well. Do you agree that I have a hardware problem? or should I try low level programming as in
| Code: | i2c_start();
i2c_write(control_byte | WRITE); // write
i2c_write(high_byte);
i2c_write(low_byte);
i2c_start(); // restart
i2c_write(control_byte | READ); // read
low_byte = i2c_read(0); // no ack
i2c_stop();
return (low_byte); |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Feb 20, 2007 8:41 pm |
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What PIC pins are you using for the EEPROM ?
What value of resistors are you using for the pull-ups ? |
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Vefa
Joined: 13 Feb 2007
Posts: 9
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| Posted: Wed Feb 21, 2007 10:19 am |
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| C3, and C4. Pull-ups are 4K. I tried 3 different 24FC515 EEPROM chips. I did a continuity test. Everything in the hardware end seems to be in good /working condition. I am using a friend's circuit and he successfully used the circuit with a similar code. Still, I can't get the code that I initially posted to work. I am a newbie and I am not sure if I am missing a very simple thing. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Feb 22, 2007 2:27 pm |
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| Post your compiler version. I'll compile the code and look at the .LST file. |
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Vefa
Joined: 13 Feb 2007
Posts: 9
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| Posted: Fri Feb 23, 2007 9:07 am |
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My compiler is PCH version 3.249.
When I compile the code with the compiler on my friend's computer, it works! When I compile it with mine it does not. We have the same compiler. I am going to try reinstalling the compiler. Any suggestion? |
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Ttelmah
Guest
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| Posted: Fri Feb 23, 2007 9:18 am |
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I posted about this quite recently.
There is a problem with certain chips, when using the hardware I2C, and a 'repeated start' command. For some reason, on these, the ACK never gets seen, and the driver will hang. Either use the software I2C (FORCE_SW), or add a 'I2C_STOP', before the restart.
Best Wishes |
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Vefa
Joined: 13 Feb 2007
Posts: 9
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| works! |
| Posted: Fri Feb 23, 2007 9:47 am |
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I checked the lst file. I saw the following statement:
| Code: | #ifndef EEPROM_SDA
....................
.................... #define EEPROM_SDA PIN_B1
.................... #define EEPROM_SCL PIN_B0
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My sda and scl pins are C3 & C4. I then realized if I defined the sda and scl pins before including the 24515.c file then it would work. That's what I did. Following is the code that works:
| Code: | #include <18F8722>
#include <stdlib.h>
#include <math.h>
#define EEPROM_SDA PIN_C4
#define EEPROM_SCL PIN_C3
#include <24515.c>
#define LED PIN_F0
#fuses HS,NOWDT,NOPROTECT,PUT,NOLVP
#use delay(clock=10000000)
main()
{
// EEPROM
long address=0;
output_high(LED);
delay_ms(1500);
output_low(LED);
while(1)
{
if(address<65535>255) output_high(LED);
else output_low(LED);
}
} // end of main |
Thanks to everyone.
Special thanks to PCM Programmer. |
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