AM2432: CLKOUT0 and RMII_REF_CLK

CLKOUT0 can be configured to source 25MHz or 50MHz. Software will need to configure the internal path to route the clock signal to the pin and then the pin mux logic would need to be configured to select that specific signal function and turn on the output buffer associated with the CLKOUT0 pin. The attached PHY device will need to be held in reset with another pin configured as a GPIO, such that it asserts reset to the PHY by default. Software will need to configure the GPIO to drive the reset signal to the inactive state after waiting for the minimum reset assertion time required by the PHY.

You should use the clock tree tool to understand how to configure the internal clock paths.  The clock tree tool is part of the SYSCONFIG tool.  Select clock tree tool in the software select dropdown and select the appropriate device after launching the SYSCONFIG tool. 

Note: The attached PHY device may see a short clock cycle or glitch on the clock signal when it is first turned on because the output buffer turn on is asynchronous to the clock transitions, so there is no guarantee the signal will be driven at the beginning of a clock cycle. This may cause problems for some attached devices. In most cases, having a short clock cycle doesn't cause a problem as long as reset is asserted when the clock glitch occurs.

Regards,
Paul

Devices with synchronous circuits are designed for a maximum operating frequency. A short cycle clock is very likely to over-clock the synchronous state machine operating the device because the short cycle clock is seen as a much higher frequency clock cycle than expected by the synchronous circuit.

This higher frequency clock cycle can violate internal timing paths in the synchronous state machine which will cause it to do unexpected things. This concern is not unique to TI Ethernet PHYs. It applies to any Ethernet PHY. However, the state machine should behave as expected as long as software asserts reset for the minimum period required by the Ethernet PHY after all power supplies and clocks are stable.

Regards,
Paul