hey Forum

I am sketching on a new gadget, vitch involves a number of i/o's. I could simply defined this number, and do the whole thing on a large (expensive) PCB.

Or I could make a "motherboard" with add-on input and output pcbs. More elegant, more flexible, and - I guess - more prone to ESD/EMC problems. My number one question is now: How robust - in terms of ESD etc. - is a I2C bus. I normaly would use some series resistors to isolate the bus from both micro and port expander, and maybee a couple of schottky diodes for additional protection. Can I then extend this bus to say 30 cm of std. ribbon cable with headers. Without getting in trouble. Speed is not an isssue.

The micro might be a P89C66x or a T89C52RD2

Any comments aprechiated.

Ha' en god dag

Per Guldmann