hardware i2c

[ZeRon]

hello
i connected an 24LC64 EEPROM to a PIC16F876 I used the 2464.c file that is available with CCS. PIN_B6 and PIN_B7 for SDA and SCL .
I just want to asked ,is this a software I2C ?
because I noticed that when using the wizard we have the option of hardware connection and normally I2C pins are C4 and C3. so is there a difference. ?

[PCM programmer]

[ZeRon]

Thx PCM programmer for your reply
but is there an advantage of hardware over software because im having trouble with reading data from the eeprom for example to fill an array
for (j=0;j<40;j++){
P[j]=read_ext_eeprom(j);
}
the array is not filled right,
note that im also using the RTC interrupt to update Pins on portB and im using PIN_B6 and PIN_B7 for i2c communication with the eeprom so might the software i2c be affected by the change of other pins on portb using rtc interrupt?

[PCM programmer]

You can find out if interrupts are causing a probelm by disabling Global
interrupts during the i2c operations.
Here's an example of how to modify an i2c function to do this.
Add the lines shown in bold to the start and the end of each i2c function.

[ZeRon]

Hello PCM Programmer
Well I changed the EXTEE example a little bit to try my hardware I2C
well it worked by using
#use i2c(Master,Fast,sda=PIN_C4,scl=PIN_C3,force_hw)
and added some lines to it
void main()
{
BYTE value, cmd ,i,j;
EEPROM_ADDRESS address;

setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);

init_ext_eeprom();
for (i=0 ;i<100;i++){WRITE_EXT_EEPROM( i+15, i );}
do {
printf("\r\n\nEEPROM:\r\n"); // Display contents of the first 64
for(i=0; i<=10; ++i) { // bytes of the data EEPROM in hex
for(j=0; j<=15; ++j) {
printf( "%2x ", READ_EXT_EEPROM( i*16+j ) );
}
printf("\n\r");
} do {

printf("\r\nRead or Write: ");
cmd=getc();
cmd=toupper(cmd);
putc(cmd);
} while ( (cmd!='R') && (cmd!='W') );

printf("\n\rLocation: ");

#if sizeof(EEPROM_ADDRESS)==1
address = gethex();
#else
#if EEPROM_SIZE>0xfff
address = gethex();
#else
address = gethex1();
#endif
address = (address<<8)+gethex();
#endif

if(cmd=='R')
printf("\r\nValue: %X\r\n",READ_EXT_EEPROM( address ) );

if(cmd=='W') {
printf("\r\nNew value: ");
value = gethex();
printf("\n\r");
WRITE_EXT_EEPROM( address, value );
}
} while (TRUE);
}

well everything worked but when i added the
for (i=0 ;i<100;i++){WRITE_EXT_EEPROM( i+15, i );}
the program would not respond
i noticed when i removed this and run the program again that the only the first byte is right "at address 15"
EEPROM:
00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 00
ff ff ff a1 ff b1 ff a1 a1 a1 ff a1 ff a1 ff a1
a1 a1 22 ff ff a1 a1 a1 ff a1 ff a1 ff a1 ff a1
ff a1 ff a1 ff a1 ff a1 ff a1 ff a1 ff b1 ff a1
ff a1 ff a1 ff a1 ff a1 ff a1 ff a1 ff a1 ff a1
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff

any ideas?
thx you again for your time

[PCM programmer]

This test program is too complicated for me.

[Heath]

What do you mean by "the program would not respond"?

[ZeRon]

never mind PCM programmer thank you for your time again .
Well ,Hello Heath,i mean that the program wouldnt continue, the "EEPROM ...." text doenst appear and program stops . when i remove the
"for (i=0 ;i<100;i++){WRITE_EXT_EEPROM( i+15, i );} "
the programs runs normally and the first 64 bytes are read.

[Heath]

Well, i'm not an expert on I2C but I would try the following.

• Try to write to one location 100 times.
  
• Try to write to just one location once.
  
• Try to write to a smaller number of locations.
  

Do you have any other kind of peripherals with this setup that communicate over the I2C bus? Do you have any other interrupts setup? (Timers, serial, etc)

Did you disable/enable interrupts like PCMP suggested?

[Heath]

One thing I noticed that would need to be changed in the future is your 'i' counter that you're using for an address. It is defined as a byte (int8). The default is unsigned so your range would be 0-255. The Write function you're using specifies a 'long int' or int16 that has a range of 0-65535.

[ckielstra]

[ckielstra]

ZeRon,

Which compiler version are you using?

When posting program code please use the 'code' buttons to preserve formatting for much easier reading.

Please post a short and complete test program. The code you have posted now is containing code you don't use (the handling of 'R' and 'W' commands) and is incomplete (missing the #fuse settings).

The easier you make it for us to read and reproduce your problem, the quicker and better responses you will get.

If you use the unmodified version of the EXTEE example can you then read and write to the EEPROM using the 'R' and 'W' commands?

[Heath]

[ckielstra]

Heath,
Ok, then I'm sorry for misunderstanding what you tried to point out.

[Heath]

no problem at all sir. I should have been clearer in my third post!