I am really stuck with an STM32 board which is mainly use to drive a 3.5" 8 bits TFT display which use the main I2C port (SCL and SDA).
I have to drive some other I2C peripheral and I planned to use the second I2C port (SD1/SCL1) but in vain.
At this time I have not find out how to use it.
Help appreciated.
For the DUE, at the beginning of your sketch, when using SCL1 / SDA1, you will have :
#include <Wire.h>
#define Wire Wire1
This will replace everywhere Wire by Wire1.
Unlike SDA/SCL, SDA1/SCL1 have no pull-ups. 2K2 as pull-up resistors connected to 3.3V would suffice.
Note that Sam3x I2C has no glitch filtering. It seems the answer is to use a fast-mode compliant isolator like the PCA9517A. The isolator filters 50ns glitches and increases fall time.