Problem with i2c eeprom.. help me...

[MONTECCHI lUCA]

Hi..
I have a problem..
I would like read and write from 16f84 to 24cxx,but I have some problem..
I define the pin for SCL and SDA, and i have use the CCS's driver, but when I use the function read_ext or write_ext in any address, dont write and dont read from Serial eeprom..
Why?
Anyone can help me?
THX!
___________________________
This message was ported from CCS's old forum
Original Post ID: 10624

[Tomi]

1. Do you have pullup resistors on both SCL and SDA?
2. Did you call init_ext_eeprom() from your early main() ?

:=Hi..
:=I have a problem..
:=I would like read and write from 16f84 to 24cxx,but I have some problem..
:=I define the pin for SCL and SDA, and i have use the CCS's driver, but when I use the function read_ext or write_ext in any address, dont write and dont read from Serial eeprom..
:=Why?
:=Anyone can help me?
:=THX!
___________________________
This message was ported from CCS's old forum
Original Post ID: 10629

[PCM programmer]

:=Hi..
:=I have a problem..
:=I would like read and write from 16f84 to 24cxx,but I have some problem..
:=I define the pin for SCL and SDA, and i have use the CCS's driver, but when I use the function read_ext or write_ext in any address, dont write and dont read from Serial eeprom..
-------------------------------------------------------

What compiler are you using ? CCS or CC5x ?
___________________________
This message was ported from CCS's old forum
Original Post ID: 10632

[MONTECCHI lUCA]

I use CCS but isn't a last version, is 3.048.
Yes,I call init_ext,but I have connect SDA and SCL to RB7 RB6 without pull-up resistor.. Is this the problem? I must use a 10k resistor?
___________________________
This message was ported from CCS's old forum
Original Post ID: 10638

[MONTECCHI lUCA]

CCS,but isn't last version. is 3.048
___________________________
This message was ported from CCS's old forum
Original Post ID: 10639

[Tomi]

Yes, you have to use 2.2kOhm or same because those pins are floating.

:=I use CCS but isn't a last version, is 3.048.
:=Yes,I call init_ext,but I have connect SDA and SCL to RB7 RB6 without pull-up resistor.. Is this the problem? I must use a 10k resistor?
___________________________
This message was ported from CCS's old forum
Original Post ID: 10640

[R.J.Hamlett]

:=I use CCS but isn't a last version, is 3.048.
:=Yes,I call init_ext,but I have connect SDA and SCL to RB7 RB6 without pull-up resistor.. Is this the problem? I must use a 10k resistor?

Yes. I2C, is defined as an 'open collector' drive bus. The chips, provide no 'pull up', and resistors are _required_. The actual value needed will depend on the capacitance of the lines, and the speed required. Normally a value between about 2.2K, and 4.7K, is typical. The bus 'idles' with the lines high, so power is only drawn through the resistors when data is being teansmitted. Without these, the bus will not work.

Best Wishes
___________________________
This message was ported from CCS's old forum
Original Post ID: 10642

[MONTECCHI lUCA]

THANKS FOR ALL!!
Now read and write OK!!
___________________________
This message was ported from CCS's old forum
Original Post ID: 10674