Ethernet Bring-up Issue – NX_UDP_Echo_Server on STM32N6570-DK

[Selvarasu_K]

Dear ST Support Team,

Thank you for your suggestion to refer to the NX_UDP_Echo_Server example and compare configurations.

I have tried to follow your recommendation, but I am still facing issues with Ethernet bring-up. Please find my observations and current status below.

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1. Current Status (My Application Logs)

• ETH HAL initialization is successful
• PHY link is coming UP
• However, it is negotiating only at 10 Mbps (Full Duplex) instead of 100 Mbps
• MAC is configured accordingly (10M Full)
• Transmission is working (ARP packets are being sent successfully)
• Reception is not working at all

Key observations from logs:

• ARP requests are transmitted:
• "ETH Tx OK len=42"
• But:
• No RX frames received
• RX descriptors remain unused (OWN bit = 0)
• Frames processed = 0
• Ping from PC is failing (Destination unreachable / timeout)

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2. Ping Result

PC Configuration:

• IP: 10.0.0.100
• Subnet: 255.255.255.0

Result:

• No successful ping response
• Board keeps sending ARP requests but does not receive any response

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3. NX_UDP_Echo_Server Example Issue

I tried to use the NX_UDP_Echo_Server example as suggested, but I am facing the following challenges:

• The example does not contain complete project structure:
• No FSBL / Application split
• Unable to directly build and flash on my board
• The example mainly includes:
• Peripheral initialization (Ethernet init)
• But no clear IP configuration / MAC handling / UDP logic visible

Due to this:

• I am unable to use it effectively as a reference
• I cannot directly run or debug the example on my hardware

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4. Request for Support

I am currently stuck at Ethernet bring-up stage. I kindly request your support on the following:

1. Could you please share a complete working Ethernet example project (buildable & flashable) for STM32N6570-DK?
• Including proper initialization
• PHY + MAC configuration
• IP setup
• Basic ping or UDP working demo
2. Based on my logs:
   Could you guide:
• PHY link is UP
• TX is working
• RX is not working
• What could cause RX path to completely fail?
• Why RX descriptors are not being updated (OWN bit remains 0)?
3. Also, PHY is falling back to 10 Mbps:
• Could this be due to RGMII delay configuration or clock issue?
• Any recommended configuration for this board?

---

I have already verified:

• DMA descriptor placement (non-cacheable region)
• PHY address
• Basic initialization flow

But still unable to receive any Ethernet frames.

---

Kindly help me with a working reference or specific guidance to resolve this issue.

Thank you for your support.

Best regards,
Selvarasu K

[MStackDev_376]

Hi,

Perhaps the Ethernet pin setup is not properly configured or your Ethernet interrupt is not configured, hence why the RX path seems silent.

You could try having a look at this ioc file and comparing it with your current one. It's part of an Ethernet Cube example for N6570-DK using the Mongoose networking library.

You could also download and run this project (to check everything is alright with your hardware) by going to the Settings tab in the URL mentioned before, selecting a directory and clicking the blue 'Generate C/C++ Code' in the upper-right corner. Then, open it with Cube, build the firmware and flash, you should then see the logs on the serial, confirming it got the IP via DHCP.

Hope this helps you!