I have a rtc module hooked to SCL/SDA which works great. I Just got a temp. sensor which runs perfect on the mega. It will not work on the Due, actually I tried two different Due boards. The I2C looks like a big issue on the DUE. Is there an I2C software library available that anyone knows of.
24.5.1 SCL and SDA PinsThese pins interface the AVR TWI with the rest of the MCU system. The output drivers contain a slew-rate limiter inorder to conform to the TWI specification. The input stages contain a spike suppression unit removing spikesshorter than 50ns.
PIO Controller Input Filter Enable Register (PIO_IFER) enables the input glitch filter on a selected I/O line for glitches with a duration < 23.8 ns. It should help but not resolve the entire issue.
When the glitch and/or debouncing filter is enabled, it does not modify the behavior of the inputs on theperipherals. It acts only on the value read in PIO_PDSR and on the input change interrupt detection.
You are right . I discovered that input filtering is supported in Sam7 thru TWIHS_FILTR register.