NUCLEO-F439ZI BOARD - MAXIMUM ETHERNET DATA TRANSMIT SPEED

[ajith1]

 

HI STM32 Team,

 

I am currently working in a ethernet based project on STM32-F439ZI Microcontroller and I am looking to transmit 100Mbps which mean 12.5 Mega-Bytes per sec. But practically I can't achieve that speed I was able to achieve 8.2MB per sec. This is because why?. In practically we cannot able to achieve Maximum speed?. What are the possible way to achieve the maximum transmit speed?. 

I have another doubt, There is any difference between integrated phy and mac microcontroller and only integrated mac and external mac. Which I means transmission speed varies because of this architecture changes?

I have attached the code for your reference,

 

Thanks and Regards,

A. Ajith Kumar

[STea]

Hello @ajith1 ,

Just need to clarify some points to help you further with your issue.
"I have another doubt, There is any difference between integrated phy and mac microcontroller and only integrated mac and external mac. Which I means transmission speed varies because of this architecture changes?"
I need to have a better understanding of your usecase.

are you implementing the F4 MCU in a custom board?

if yes what is the external Phy you are using?

in which mode you are implementing Ethernet MII or RMII can you share some info about your speed configuration GPIO settings schematics...?
BR 

[Andrew Neil]

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@ajith1 wrote:

 I was able to achieve 8.2MB per sec.

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How did you measure that, and in what network setup?

 

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@ajith1 wrote:

In practically we cannot able to achieve Maximum speed?.

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The 100Mbps is the raw signalling rate on the wire; there will always be overheads, so you will never achieve 100Mbps of payload throughput.

See, for example:

https://www.gigabit-wireless.com/gigabit-wireless/actual-maximum-throughput-gigabit-ethernet/

(it is talking about Gigabit Ethernet, but similar applies to 100Mbit)

 

Also, on a real network, there will also be other traffic consuming bandwidth.

And there may be delays (software & hardware) in the devices at each end of the link.

 

[ajith1]

What is the maximum efficiency of Ethernet that we can achieve in practical.

[LCE]

I think I have seen users claiming to reach about 94 Mbit / s TX & RX each with the Nucleos.

But I don't know if that was possible using the ETH HAL stuff...

I'm using F7 and H7, and 90 Mbps is no problem. But not using ETH HAL...

One thing you might want to check:
Maybe the transfer is slowed by the PC / windows side. Somewhere in the Windows 10 registry there's a setting for TCP / MTU, that was set to 1200 on my computer.

Just found my notes:

• MSS is TCP's maximum segment size is 1460 Bytes per packet, which is fully used by the device to reduce TCP overhead.
  • ATTENTION! This might be limited by Windows settings and can only be changed via the registry, by changing the MTU (maximum transfer unit) to 1500 Bytes (0x5DC), see method 3 in:
    https://support.microsoft.com/en-us/topic/recommended-tcp-ip-settings-for-wan-links-with-a-mtu-size-of-less-than-576-2312050e-2a1b-1e89-94a1-b2868afa436f
  • This can be checked via Wireshark showing the packet / data size
  • It must be set to the above values, otherwise packet fragmentation on the device side will slow down the interface significantly.