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| page writes to eeprom |
 Posted: Sun Mar 06, 2005 12:35 am |
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| does anyone know how write to the external eeprom in page mode? |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Re: page writes to eeprom |
| Posted: Sun Mar 06, 2005 4:41 am |
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| Anonymous wrote: | | does anyone know how write to the external eeprom in page mode? |
Which external eeprom do you mean? Do you have a type number for us? |
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rwyoung
Joined: 12 Nov 2003
Posts: 563
Location: Lawrence, KS USA
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| Posted: Sun Mar 06, 2005 8:53 am |
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If you mean something related to the 24C64/128/256 (the only ones I've tested this with) it is pretty easy but I was a little bit lazy and didn't try writing it in a more RAM efficient way since this particular routine is being used on a PIC18 and I am only expecting to be using about 25% of total RAM anyway.
| Code: | /*
* void writepage_ext_eeprom(long int address, char *data)
*
* Purpose : Write 64 byte page to external EEPROM at particular address.
* Uses ACK polling to find end of eeprom write cycle.
* Parameters : address - 16 bit int for address
* *data - pointer to array of 64 bytes to write
* Calls : various
* Returns : none
* Notes : TODO : change device address to #def'd value
* Tested :
*/
void writepage_ext_eeprom(long int address, char *data)
{
int8 i;
i2c_start();
i2c_write(0xA0);
i2c_write(make8(address,1));
i2c_write(make8(address,0));
for(i=0;i<64;i++)
{
i2c_write(data[i]);
}
i2c_stop();
// eeprom ACK polling
do {
i2c_start();
} while(i2c_write(0xA0));
}
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_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month! |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Sun Mar 06, 2005 9:21 am |
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Here are some code snippets that if you read them will give you idea of what to do. Note that the page size is dependant upon the chip used. I believe this code was for a 24C08 (actually 2 of them)
| Code: |
#define I2C_IDLE() while ((SSPCON2 & 0x1F) || (SSPSTATbits.R_W))
#define I2C_START() \
SSPCON2bits.SEN = 1; \
while (SSPCON2bits.SEN) \
{ \
_asm nop _endasm \
}
#define I2C_RESTART() \
SSPCON2bits.RSEN = 1; \
while (SSPCON2bits.RSEN) \
{ \
_asm nop _endasm \
}
#define I2C_STOP() \
SSPCON2bits.PEN = 1; \
while (SSPCON2bits.PEN) \
{ \
_asm nop _endasm \
}
#define I2C_WRITE(x) \
SSPBUF = (x); \
while (SSPSTATbits.BF) \
{ \
_asm nop _endasm \
} \
I2C_IDLE()
#define I2C_READ(x) \
SSPCON2bits.RCEN = 1; \
while (SSPCON2bits.RCEN) \
{ \
_asm nop _endasm \
} \
SSPCON2bits.ACKDT = (x); \
SSPCON2bits.ACKEN = 1; \
while (SSPCON2bits.ACKEN) \
{ \
_asm nop _endasm \
}
/* *************************************************************************
DESCRIPTION: This function writes a block of data to the SEEPROM
RETURN: none
ALGORITHM: none
NOTES: The routine should handle going across chip boundaries
*************************************************************************** */
void I2C_Write_Block(
uint8_t device, /* I2C address of the device that we are writing to */
char *data, /* pointer to the block of data to write */
uint8_t len, /* number of bytes to write */
uint16_t address) /* EEPROM address to write data */
{
uint8_t control;
uint8_t lastpage;
uint8_t page;
/* determine the control word for the device */
control = device | ((uint8_t) (address >> 8) << 1);
/* Wait until our device is ready */
while (!I2C_Device_Ready(control));
/* Set the address pointer in the device */
I2C_WRITE((uint8_t) address);
page = (uint8_t) address >> 4;
lastpage = page;
while (len)
{
if (page != lastpage)
{
/* Issuing a STOP will start the write sequence */
I2C_STOP();
lastpage = page;
/* determine the control word for the device */
control = device | ((uint8_t) (address >> 8) << 1);
/* Wait until our device is ready */
while (!I2C_Device_Ready(control));
/* Set the address pointer in the device */
I2C_WRITE((uint8_t) address);
}
I2C_WRITE(*data);
data++;
address++;
/* The 24C08 has a 16 byte page for writing. */
page = (uint8_t) address >> 4;
len--;
}
I2C_STOP();
}
/* *************************************************************************
DESCRIPTION: This function checks to see if an i2c device will ACK
RETURN: TRUE if device ACKed otherwise FALSE
ALGORITHM: none
NOTES: none
*************************************************************************** */
static bool I2C_Device_Ready(
uint8_t id) /* FIX ME: add comment */
{
do
{
/* Important to clear these bits before we attempt to write */
PIR2bits.BCLIF = 0;
SSPCON1bits.WCOL = 0;
I2C_IDLE(); /* ensure module is idle */
I2C_START();
} while (PIR2bits.BCLIF);
I2C_WRITE(id);
if (!SSPCON2bits.ACKSTAT) /* test for ACK condition, if received */
return (TRUE);
return (FALSE);
}
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drolleman
Guest
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| Posted: Sun Mar 06, 2005 11:43 am |
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| thank for the info, it's just what i needed |
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