MSP432E401Y: External OSCO Frequency for PHY Clock with best Ethernet operation

Bert van de Luijtgaarden

Part Number: MSP432E401Y
Other Parts Discussed in Thread: MSP-EXP432E401Y,

Dear E2E Support Expert,

We intend to connect to the OSC0 input port pin 88 an external 120 MHz (or 100 MHz) signal acting as MOSC for our SimpleLink™ Ethernet MSP432E401Y Microcontroller LaunchPad™ Development Kit (MSP-EXP432E401Y).

Specs says up to 120 MHz max.

Kit Descriptions says for Ethernet PHY operation it should be 25 MHz .

Question what is really needed?

Could we use the GPIO (PM4) instead if we connect to this port 25 MHz and mux it properly?

Please refer to Figure 4-5. Main Clock Tree of document SLAU723A–October 2017–Revised October 2018

It looks like the Ethernet ""PHY Clock"" should be a real 25 MHz signal.

Thanks and kind regards

Bert

over 5 years ago

0 Hawken Li over 5 years ago

TI__Intellectual 2585 points

Hi,

OSC0 is the main clock which should be 25Mhz max with PLL and 120MHz max without PLL.

For ethernet interface, the clock sources are 3 types which is mentioned in slau723a:15.3.1.

PM4 has no such function that mux with ethernet osc.

0 Hawken Li over 5 years ago in reply to Hawken Li

TI__Intellectual 2585 points

Hi,

If you have any question,please show out but not to directly click the reject button.

For ethernet phy interface, it should be 25MHz. You could either choose 25MHz from osc0 or sysclk or en0tx/rxck.

In your case, please use mosc from external 120Mhz, and set sysclk to 25Mhz for ethernet.

Arm-based microcontrollers

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MSP432E401Y: External OSCO Frequency for PHY Clock with best Ethernet operation