TJA1410_10Base_T1s

[wuxianlong]

Hi,NXP

I am testing 10BASE-T1S using the S32K5 and TJA1410. Currently, I can see waveforms on the TX pin, and there are also waveforms on the RX and ED pins, which indicates that signals can be received on the MDI. However, the TX pin is unable to send data to the MDI.

TX_RX_ED-2026-09-10-19-26-50.bmp
Best Reagrds.
xianlong

[PavelL]

Hello @wuxianlong ,

I hope this email finds you well. I am writing to you in regard to a product currently in your possession – an NPI (New Product Introduction) - S32K5 - which has not been officially launched yet.

Please be advised that customers who have been granted early access to such products have assigned their field engineers. Your designated field engineer should serve as your primary support channel for any issues, concerns or queries you may have about this product.

Our online support team will be opening a wider range of support for this product once it has been officially released. Until then, we will not be equipped to provide the desired assistance.

We appreciate your understanding in this matter.

Thank you for your understanding.

Best regards,

Pavel

[PavelL]

Hello @wuxianlong ,

How have you measured the MDI? MDI is differential interface so you need to use differential oscilloscope probe. MDI requires proper differential termination - please refer to AN14787 - Application note 10BASE-T1S Ethernet PMD transceiver TJA1410, Rev. 1.0 , chapter 3.3.

Best regards,

Pavel

[wuxianlong]

Hi,@PavelL 

I did not use a differential probe. When I transmit (TX), the MDI shows no fluctuation on the oscilloscope — it remains flat/horizontal. However, when the PC sends data, the MDI clearly shows a differential waveform. It feels like the TJA1410 is not being correctly switched into transmit mode and the chip remains in normal mode. Are there any methods to verify the PHY's current mode? Currently, our TJA1410 is not connected to an SMI interface — what precautions should we take regarding this?

Best Regards,
xianlong

[PavelL]

Hello @wuxianlong ,

Since S32K5 is an NPI device, please note that we are currently unable to validate the complete S32K5 and TJA1410 setup on our side.

The TJA1410 operating mode is not selected through the SMI interface. The transitions between Normal and Transmitting modes are controlled by commands received on the TX pin. Therefore, observing data activity on TX does not necessarily confirm that the TJA1410 has entered Transmitting mode. The preceding TRANSMIT command and its timing must also comply with the timing specified in the TJA1410 data sheet.

Please verify the transition from Normal to Transmitting mode according to Figure 10 in the TJA1410 data sheet. In particular, please capture the TX command together with the differential VLINE signal and ED output. This should confirm whether the TJA1410 recognizes the TRANSMIT command and activates its MDI transmitter.

Best regards,

Pavel