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ljbeng
Joined: 10 Feb 2004
Posts: 205
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| If interested.... Code for Multiple 24LC256 |
 Posted: Mon May 03, 2004 9:29 am |
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I have a box that uses 8 24LC256 external eeproms. I modified 24256.c to allow for addressing all 8 chips. My board has the address line (A0,A1,A2) of the eeproms tied to +5 or ground to create a different address for each chip. With this code you can put up to 8 eeproms on the same board and get 32K bytes x 8 chips = 256K bytes of memory.
| Code: | ///////////////////////////////////////////////////////////////////////////
//// Library for Multiple 24LC256 serial EEPROMs ////
//// ////
//// init_ext_eeprom(); Call before the other functions are used ////
//// ////
//// write_ext_eeprom(c, a, d); Write the byte d to the address a ////
//// using chip c ////
//// ////
//// d = read_ext_eeprom(c, a); Read the byte d from the address a ////
//// using chip c ////
//// ////
//// c = chip address: Pins a0, a1, a2 of chip define address for ////
//// each 24256 chip up to 8 chips can be addressed////
//// ////
//// Change the pin assignments inside the #use i2c statement ////
//// ////
///////////////////////////////////////////////////////////////////////////
#use i2c(master, sda=PIN_C4, scl=PIN_C3)
#define EEPROM_ADDRESS long int
#define EEPROM_SIZE 32768
void init_ext_eeprom()
{
output_float(PIN_C3);
output_float(PIN_C4);
}
void write_ext_eeprom(BYTE chadd,long int address, BYTE data)
{
short int status;
chadd = (chadd<<1) + 0xa0;
i2c_start();
i2c_write(chadd);
i2c_write(address>>8);
i2c_write(address);
i2c_write(data);
i2c_stop();
i2c_start();
status=i2c_write(chadd);
while(status==1)
{
i2c_start();
status=i2c_write(chadd);
}
}
BYTE read_ext_eeprom(BYTE chadd,long int address) {
BYTE data;
chadd = (chadd<<1) + 0xa0;
i2c_start();
i2c_write(chadd);
i2c_write(address>>8);
i2c_write(address);
i2c_start();
chadd = chadd | 1;
i2c_write(chadd);
data=i2c_read(0);
i2c_stop();
return(data);
} |
Last edited by ljbeng on Mon May 03, 2004 10:32 am; edited 1 time in total |
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Humberto
Joined: 08 Sep 2003
Posts: 1215
Location: Buenos Aires, La Reina del Plata
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| Posted: Mon May 03, 2004 9:37 am |
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Hi ljbeng,
Good 
Thanks for upload & share !!! 
Humberto |
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Gabriel Caffese
Joined: 09 Oct 2003
Posts: 39
Location: LA PLATA, ARGENTINA
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| Thanks for sharing, but... |
| Posted: Mon May 03, 2004 10:17 am |
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Ljbeng,
Thanks for sharing your code, but take care that 24256 eeproms are 32kbyte size, so 8*32kb = 256kbytes !! |
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ljbeng
Joined: 10 Feb 2004
Posts: 205
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| Posted: Mon May 03, 2004 10:31 am |
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| Your right, bad math on my part. I thought that sounded low. |
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