Bringing this up again.
Just a question on the post below.
Anything larger than 4.7k. By larger, I assume you mean a higher ohm resistor, as in 10k for example?
Just wanted to double check.
I am using I2C extensively in a design I have, using multiple Adum1250 I2C Expander/isolation chips. I currently have the design using 1k resistors on both sides of each of the chips - and I ideally want the highest throughput possible as it is the 'backbone' for comms between about 10+ boards.
The devices connected are other AVR's (328's, 644P's or 1284P's), I2C Expension Chips MCP23017's, an EEPROM and a DS1307 RTC.
I have modified the wire library to be 400000L rather than 100000L (as detailed in another post), and I just spotted the TWBR = 12 comment on here, so will try that too.
I have read Nick's forum and the experiments made with pullup resistors etc, 2.2k giving a nice square wave etc, however I am still not sure what the ideal resistance is in my case, and for highest speed.
I am sure it has been covered, however if someone can spell it out for me that would be great. Is 1K suitable or should I change it.
Thanks