Required assitance on ethernet loopback testing for MCF54415 processor.

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Required assitance on ethernet loopback testing for MCF54415 processor.

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Contributor I

Hi all,

 

     We are using the MCF54415 processor for our project and we are now trying to perform the ethernet testing. To make sure that the Ethernet(both hardware and software) is working fine, we are planning to have a loopback testing. but there are no more documents explaining on this.:(

can anyone pls help me in performing the loopback testing on this board??

 

The setup of board is as follows:

The MAC-NET core is  using KSZ8021RNL PHY transceiver to communicate to the outside world.

The communication with the PC is working fine(this was done as using our board as the server and PC as the client).

 

To avoid the dependency on PC every time to test the board we are thinking to do loopback test..

So please do guide me on performing the loopback test..

Thank you in advance...

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Specialist I

> development of a loopback code for this processor (either using sockets, ARP request, or anything else)

All of those protocol levels assume you're connected to a network, and connected to something else you can send addressed packets to

To do what you want you have to send and receive raw ethernet packets.

You didn't say what software or operating system or network stack you're using. It may have a "send raw packet on ethernet" and "receive all packets from ethernet" interface function. If it doesn't, you'll have to hire a programmer to write one.

You're not testing it properly with loopback. The hardware may have a fault where it can talk to itself, but not talk to anything else. Ethernet requires tight tolerances on the crystal controlling the Ethernet timing. It is either "100 ppm" or "+- 50 ppm" (refer to your data sheets or the relevant Ethernet standards documents). If you're not separately measuring the generated frequency against an external reference, then it might be wrong. If it is a long way out of spec (10000 ppm or more) then you can't exchange any packets with external devices, but it WILL pass loopback tests. If it is over 100 ppm but less than "a bit more than that", you can send and receive short packets, but not long ones. If you're directly connected to the test device you can be a lot further out of spec than if you're sending through a switch or hub, so you should try and test through a hub or switch with maximum-length Ethernet frames.

Tom

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NXP Employee
NXP Employee

Hi Hemanth,

Did you find a solution?

If not you can make a loop back cable:

How to Create a RJ45 Ethernet Loopback Cable/Connector | Cisco Console

Regards,

David

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Contributor I

Hi David,

Thank you for the link. But still the issue is not cleared. I needed the help on implementing the external loopback for the prcoessor MCF54415's Ethernet along with the above mentioned PHY.

regards,

Hemanth

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NXP Employee
NXP Employee

Hi Hemanth,

Once you have validated that a board is working correctly with respect to Ethernet, you could use it as your Ethernet test fixture and not reply on a PC.

Regards,

David

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Contributor I

Hi David,

Our process inculdes the producing of many cutomised boards using this processor, and each board has to undergo testing of each peripheral as well as the Ethernet, so we are thinking to use the loopback test which is easy and independent of the PC.

So i needed guidance on the development of a loopback code for this processor (either using sockets, ARP request, or anything else) using the exernal loopback (TX pins tied to RX pins).

Hoping for a reply on this soon..

Regards,

Hemanth

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26 Views
Specialist I

> development of a loopback code for this processor (either using sockets, ARP request, or anything else)

All of those protocol levels assume you're connected to a network, and connected to something else you can send addressed packets to

To do what you want you have to send and receive raw ethernet packets.

You didn't say what software or operating system or network stack you're using. It may have a "send raw packet on ethernet" and "receive all packets from ethernet" interface function. If it doesn't, you'll have to hire a programmer to write one.

You're not testing it properly with loopback. The hardware may have a fault where it can talk to itself, but not talk to anything else. Ethernet requires tight tolerances on the crystal controlling the Ethernet timing. It is either "100 ppm" or "+- 50 ppm" (refer to your data sheets or the relevant Ethernet standards documents). If you're not separately measuring the generated frequency against an external reference, then it might be wrong. If it is a long way out of spec (10000 ppm or more) then you can't exchange any packets with external devices, but it WILL pass loopback tests. If it is over 100 ppm but less than "a bit more than that", you can send and receive short packets, but not long ones. If you're directly connected to the test device you can be a lot further out of spec than if you're sending through a switch or hub, so you should try and test through a hub or switch with maximum-length Ethernet frames.

Tom

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