I'm using an Altera APEX20KE with 200k gates on a bought FPGA board. The Clocks 1 and 2 of the FPGA are used by the board, the Clocks 3 and 4 are free. I testet the i2c-core from opencores.org working with the onboard clock on Clock-Pin 2 and it works fine. If I connect (just connect not use in the FPGA, I'm still using the onboard clock from Clock-Pin 2) an own clock to the two free Clock-Pins, the i2c-core doesn't work anymore !!! :-( If I use my own clock on Clock-Pin 3 or 4 as clock-input for the i2c-core, it doesn't work too.
I can't understand this behaviour
Please Help
Manfred