I2C PIC16F876 PCF8583 24C16 - Problem

[H. Schleyer]

Hi PIC-folks,

I've trouble with reading the time of the 8583.
Address-Pin PCF8583 -> +5V
Address-Pins 24C16 -> GND (As I know: not connected internally, anyway)

I got wrong data when using read_pcf(4) (hours).
reading seconds ,days etc works fine!
Writing hours works, too.
Reading and writing EEProm: no problem.

Am I mad?

Here's the code:

#define EEPROM_SDA PIN_C4
#define EEPROM_SCL PIN_C3

//#endif

#use i2c(master,sda=EEPROM_SDA, scl=EEPROM_SCL)

#define EEPROM_ADDRESS long int
#define EEPROM_SIZE 2048


#define hi(x) (*(&x+1))

void init_ext_eeprom() {
output_float(eeprom_scl);
output_float(eeprom_sda);
}

#separate
void write_ext_eeprom(long int address, byte data) {

i2c_start();
i2c_write((0xa0|(byte)(address>>7))&0xfe);
i2c_write(address);
i2c_write(data);
i2c_stop();
delay_ms(11);
}

#separate
byte read_ext_eeprom(long int address) {
byte data;

i2c_start();
i2c_write((0xa0|(byte)(address>>7))&0xfe);
i2c_write(address);
i2c_start();
i2c_write((0xa0|(byte)(address>>7))|1);
data=i2c_read(0);
i2c_stop();
return(data);
}

#separate
void write_pcf(byte address, byte data)
{
i2c_start();
i2c_write(0xa2);
i2c_write(address);
i2c_write(data);
i2c_stop();
}

#separate
byte read_pcf(byte address)
{
byte data;
i2c_start();
i2c_write(0xa2);
i2c_write(address);
i2c_start();
i2c_write(0xa3);
data = i2c_read(0);
i2c_stop();
return(data);
}

Thanks for help!
___________________________
This message was ported from CCS's old forum
Original Post ID: 4226

[johnpcunningham]

Do you have pull-ups on the SDA and SCL lines? I wouls suggest something around 2.1K on each from my I2C experiences. I2C is sensitive to rise and fall times on some devices so the "hotter" pullup workes better.
___________________________
This message was ported from CCS's old forum
Original Post ID: 4235

[PCM programmer]

<font face="Courier New" size=-1>:=I got wrong data when using read_pcf(4) (hours).
:=reading seconds ,days etc works fine!
:=Writing hours works, too.
-----------------------------------------------

Give us some examples of the failure.

ie., if you write 00, or 10, or 23, what do you read back ?
etc.

Note: The above numbers are intended to be in BCD format,
so you would actually write 0x00, 0x10, and 0x23 to
the hours register.</font>
___________________________
This message was ported from CCS's old forum
Original Post ID: 4249

[H. Schleyer]

writing the time works. Reading is fine as long the hour is not changing. Then Hours are 00. (BCD, of course).
when I pull the 24C16 of socket, time reading is fine.
So I think it's something with addressing.



:=<font face="Courier New" size=-1>:=I got wrong data when using read_pcf(4) (hours).
:=:=reading seconds ,days etc works fine!
:=:=Writing hours works, too.
:=-----------------------------------------------
:=
:=Give us some examples of the failure.
:=
:=ie., if you write 00, or 10, or 23, what do you read back ?
:= etc.
:=
:=Note: The above numbers are intended to be in BCD format,
:= so you would actually write 0x00, 0x10, and 0x23 to
:= the hours register.</font>
___________________________
This message was ported from CCS's old forum
Original Post ID: 4337

[H. Schleyer]

sure. tried 1k and 10k. same effect.

:=Do you have pull-ups on the SDA and SCL lines? I wouls suggest something around 2.1K on each from my I2C experiences. I2C is sensitive to rise and fall times on some devices so the "hotter" pullup workes better.
___________________________
This message was ported from CCS's old forum
Original Post ID: 4338

[Guest]

Give me an example how to write minutes and hours into 8583.