PTA9 and PTA10 on K60 Microcontroller

[Arun_bel]

Hi,

 PTA9 and PTA10 on K60 Microcontroller are having dual functionality of MII signls and also Trace Signals for JTAG. If I Want to use K60 as MII MAC and also I want to provide full JTAG functionality how I can do that as the Pin has Multiplexed Signals.

Kindly Can anyone clarify me.

Regards

Arun

[mjbcswitzerland · Accepted solution]

Hi Arun

Trace requires a certain amount of signals and so means sacrificing some ports to be able to use it.

In the case of PTA9 and PTA10 these are multiplexed with MII0_RXD2 and MII0_RXD3 (as well as FTM functions). If the Ethernet PHY is used in RMII mode (rather than MII mode) these pins are not needed and so can be allocated to the trace interface.

Supposedly freescale put the trace pins to overlap with more obscure peripheral functions so that trace can be used in as many cases as possible - since using RMII Ethernet PHY mode would also allows this it offers the designer the opportunity to decide on the RMII mode in case trace is a requirement (if MII0_RXD0 were to be multiplexed instead there would be no option to use trace together with Ethernet!).

However it is a compromise and so, if all peripheral port signals are required in a design, trace would not be possible without disabling these pins (and these functions in the application). In some cases it may be possible to still use a trace port together with a SW version that doesn't use all of its normal peripheral functions but instead ensures that all trace signals are configured for the trace connector. Whether, in this case, trace makes sense depends on what is being monitored/debugged.

Regards

Mark

[Arun_bel]

Then it means I have to use Etherenet PHY in RMII mode only if I want use trace functionality. Also since RMII mode MAC clock is internally tied to OSCERCLK, I have to use only 50MHz crystal source for EXTAL pin, not 25MHz. Am I correct? Also same crystal clock source should be used to drive both microcontroller and PHY tranceiver? 

[mjbcswitzerland]

Hi

Yes, the circuits is used like that in the tower kit.

Regards

Mark