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AdamkT1
Joined: 21 Apr 2007
Posts: 44
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| EEPROM 24C512 R/W Problem, Need Help |
 Posted: Sat Jul 07, 2007 3:59 am |
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I am trying to develop the driver for 24C512 EEPROM but so far I am having problems.
My desire is to write and read from the address 1.
Need help...
Below is the code:
| Code: | #include <18F452.h>
#include "24C512.c"
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
void main()
{
int8 n;
EEPROM_ADDRESS address;
SET_TRIS_A(0);
SET_TRIS_C(0);
SET_TRIS_D(0);
PORTA=0xFF;
PORTB=0xFF;
PORTC=0xFF;
PORTD=0xFF;
delay_ms(500); //let the system to stabilize
address=1;
PORTC=0;
PORTD=0;
delay_ms(500);
while (TRUE)
{
for (n=1; n<100;n++)
{
write_ext_eeprom(address, n);
PORTC=n;
delay_ms(200);
PORTD=read_ext_eeprom(address);
delay_ms(200);
}//end for
}//end while
} |
========24C512.C=================
| Code: | #use delay(clock=20000000)
#ifndef EEPROM_SDA
#define EEPROM_SDA PIN_B1
#define EEPROM_SCL PIN_B0
#endif
#define EEPROM_ADDRESS long int
#define EEPROM_SIZE 65535
void start_ext_eeprom()
{
output_low(EEPROM_SCL);
output_high(EEPROM_SDA);
output_high(EEPROM_SCL);
delay_ms(1);
output_low(EEPROM_SDA);
delay_ms(5);
}
void stop_ext_eeprom()
{
output_low(EEPROM_SCL);
output_low(EEPROM_SDA);
output_high(EEPROM_SCL);
delay_ms(1);
output_high(EEPROM_SDA);
delay_ms(5);
}
void clock_data(Byte data)
{
int8 ctr;
for(ctr=0; ctr<8; ctr++)
{
output_bit(EEPROM_SDA, shift_left(&data,1,0));
output_high(EEPROM_SCL);
delay_ms(1); // let the pin stabilize
output_low(EEPROM_SCL);
delay_ms(1); //let the pin stabilize
}
delay_ms(5); // delay for EEPROM write cycle
}
void write_ext_eeprom(long int address, BYTE data)
{
start_ext_eeprom();
clock_data(0xa0); // Device address & R/w bit is low
while (input(EEPROM_SDA));
clock_data(address>>8);
clock_data(address);
while (input(EEPROM_SDA));
clock_data(data);
while (input(EEPROM_SDA));
stop_ext_eeprom();
}
BYTE read_ext_eeprom(long int address)
{
int8 ctr;
BYTE data;
start_ext_eeprom();
clock_data(0xa0); // Device address & R/w bit is High
while (input(EEPROM_SDA));
clock_data(address>>8);
clock_data(address);
while (input(EEPROM_SDA));
start_ext_eeprom(); //Send start again
clock_data(0xa1); // Device address & R/w bit is low to READ
while (input(EEPROM_SDA));
//===========read the data===================
for(ctr=0; ctr<8; ctr++)
{
shift_left(&data,1,input(EEPROM_SDA));
output_high(EEPROM_SCL);
delay_ms(1); // let the pin stabilize.
output_low(EEPROM_SCL);
delay_ms(1); // let the pin stabilize.
}
stop_ext_eeprom();
return(data);
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat Jul 07, 2007 10:49 am |
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You're not using the CCS driver.
Use the CCS driver. Here's the file location:
| Quote: | | c:\Program Files\PICC\Drivers\24512.c |
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AdamkT1
Joined: 21 Apr 2007
Posts: 44
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| Posted: Sat Jul 07, 2007 6:04 pm |
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I have tried the driver also but that too does not seem to work. The program just hangs in the first write statement of the driver after the start statement.
Besides as a learner, I wish to do it myself.
Can some body highlight the mistake in the code?
The only idea left with me, is that may be, the pin SDA is not configured as an input that is why the value read is always a Zero.
Thanks for the reply.  |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat Jul 07, 2007 6:38 pm |
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If the CCS driver doesn't work, then there is something wrong with your
hardware. That's why I suggested that you try it first. Now you should
look closely at your connections, etc. Do you have pull-up resistors
on the SDA and SCL lines ? |
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AdamkT1
Joined: 21 Apr 2007
Posts: 44
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| Posted: Sat Jul 07, 2007 6:43 pm |
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No pullups.
Can you provide me any hardware requirements.
Thanks again. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Sat Jul 07, 2007 6:45 pm |
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Add a pull-up resistor to +5v on each of SDA and SCL. Use 4.7K ohm
resistors. |
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AdamkT1
Joined: 21 Apr 2007
Posts: 44
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| Posted: Sat Jul 07, 2007 6:48 pm |
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Ok.
I would need a little time to make that happen as I am not very good at hardware.
Appreciate the prompt responses. Thank you. |
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AdamkT1
Joined: 21 Apr 2007
Posts: 44
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| Posted: Sun Jul 08, 2007 1:26 am |
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Its working fine now.
Thanks for the support.
I wish I could send the proteus file for new comers, as I see that this topic has been discussed so many times.
Thanks again
 |
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