Firstly, I use an unofficial ethernet shield (with W5200 chip) with the new arduino due.
I modified the W5100 library for the W5200 chip and all the exemple sketches run very well.
The W5200 chip support a SPI clock at 80 Mhz and refering to the SAM3X8E datasheet (page 29), the arduino due 32bits ARM uC support a Max of 65 Mhz clock SPI.
Ok, now my question :
In the "void W5100Class::init(void)" function located in the "W5100.cpp"
When I set the SPI clock divider at the number 1 using "SPI.setClockDivider(1)" (to use the full 65 Mhz SPI clock speed), it is impossible to use the ethernet shield (not responding ??)
But if I comment my code (no call to SPI.setClockDivider at all) or if I set the clock divider at 2, all run well.
Why can I not set the clock divider at 1? And by default, when no call to SPI.setClockDivider() is called, at which speed is the SPI clock?
Any hint for me?