i2c help

Zap-o

So I am learning how to use an i2c bus and I am embarrassed to admit that I cant seem to find my Ic's Slave Address. The device is a M41t0 RTC and the data sheet is

www.st.com/stonline/books/pdf/docs/9105.pdf

I am not sure but I think that the address is D0 hex. Could someone be so kind to verify this and help me with further questions while I attempt to learn?

Post Edited (Zap-o) : 9/17/2009 2:07:58 PM GMT

Timmoore

Yes D0 hex, section 2, 2nd sentence

Zap-o

Wow this i2c stuff is nice. Thanks Timmoore for the back up.

My next question is : If the Eeprom on the prop board is connected to another i2c device wont the propeller tool programmer not place the code on the propeller when using 2 pull up resistors? If i recall I used two pull up resistors in the past and noticed this problem. Currently I use 1 pull up.

Timmoore

Shouldn't be a problme, the prop prototype board using 2 resistors ( I assume you mean 1 on scl and 1 on sda). You need to check the board oyu are using, you shouldn't add resistors if the pin already has them. I have seen this problem before when the I2C device is a 5V device and it doesn't detect the 3V as a high - most work but some don't. I use the following

prop pin (scl/sda) has 10K resistor to 3.3V, then a 1K inline resistor,then a 4K7 resistor to 5V

3.3V volt I2C devices connect to the prop side of the 1K inline resistor
5V I2C devices connect to the farside (away from prop) of the 1K inline resistor

Heres the circuit drawn in spin