Hi,

Can you disconnect and make pin float to measure its voltage?

Regards,

Zoey

We have the 2K pull up resistor, when float, it shall high.

We did the below test,  disconnnect MDIO and MDC with MSPM0L1306.

Connect with seperate C2000 P65x controlcard, it can read back data successfully and aslo the Phy can pulled down the MIDO as expected.

Hi,

Yes I have also tested from my side, it is the same as you. It seems that it is not caused from MCU.

The pull down resistor should be 40kΩ, please make check once you connect to MDIO and MDC, is there any pull up resistor to divide the voltage.

Regards,

Zoey

I already posted that MDIO have 2K pull up resistor. And MDC have no, there is NC.

What do you mean that you tested and the same as me?  Your Phy chip also cannot pull down the MDIO signal to GND?

No, I just test based on launchpad and leave input GPIO float to test its voltage. The result shows that it is ~0mV.

What is your code to leave input GPIO float？

And test this state voltage, help which side to my question?

Hi,

I mean from hardware side, please make MCU IO port float, which mean do not connect anything include your pull- up resistor. And just use MCU internal pull-down resistor to see if the voltage can be ~0V. 

Regards,

Zoey

Have the pull-up resistor is the typical applciation for MIDO. The pull-up resistor is 2KΩ.

And I also tested that use C2000 P65x as the MCU to communicated with the same Phy(The same board, just disconnect with TI M0L1306, MDIO-PA16 and MDC-PA10 PIN). When Phy want to output the low signal, it can pull down to GND.

So what is difference between C2000 and M0L1306 of input I/O part.

I also us the M0L1306 controlpad, when config as input and pull down resistor, measure the voltage, it is low to gnd.