Nucleo f767zi force ethernet at 10Mbps

Mbed OS
1

Hi,

In order to ease troubleshooting, I’d like to force my ethernet link to run at 10Mbps.
This would permit to observe packets with an affordable oscillocope.
I understand that I should disable auto-negociation and deselect 100Mbps in PHY init.
But I have no idea about doing this.
EthernetInterface doesn’t provide any adequat API.

all the best

Jean-Paul

2

Hello Jean-Paul,

Try to make the following modification to the ‘mbed-os\features\netsocket\emac-drivers\TARGET_STM\stm32xx_emac.cpp’ file:

bool STM32_EMAC::low_level_init_successful()
#ifndef ETH_IP_VERSION_V2
{
    /* Init ETH */
    uint8_t MACAddr[6];
    EthHandle.Instance = ETH;
//    EthHandle.Init.AutoNegotiation = ETH_AUTONEGOTIATION_ENABLE;
//    EthHandle.Init.Speed = ETH_SPEED_100M;
    EthHandle.Init.AutoNegotiation = ETH_AUTONEGOTIATION_DISABLE;
    EthHandle.Init.Speed = ETH_SPEED_10M;
...
}
3

Hello Zoltan,

Sorry for the mbed-newbie question. I am using online compiler.
Is it possible to modify the mbed library ?
If yes, how to ?

Regards

JP

4

I’m afraid not. Try to do it offline either in Mbed Studio or using Mbed CLI.

Best regards, Zoltan

5

Hello again,

I have tested your recommendation, it works great!
For conveniance, I wrapped your code with an “ETH_FORCE_SPEED_10M” #ifdef (see here below).
Regards,

Jean-Paul

ether10Mbps
ether10Mbps703×477 27.3 KB