STM32F765 Ethernet

lb2 · ‎2024-06-24

I'm trying to get Ethernet working with STM32F765VIH MCU and developing using Keil MicroVision and CubeMX 6.11.1

When setting up CubeMX I'm seeing warning message that RAM needs to point to 0x24000000 for ethernet to work.
I don't see an option for setting ETH RX Buffer Address like in previous versions of CubeMX. Has this been renamed or moved somewhere else.

STea · ‎2024-07-16

Hello @lb2 ,

It is not recommended to have two MCUs communicate with a single PHY (such as the LAN8742) simultaneously using different interfaces (RMII and MII).

In fact, the LAN8742 PHY is typically configured to work with either RMII or MII, but not both simultaneously. The configuration is usually set during the initialization phase and is dependent on the hardware design and software configuration. RMII and MII have different clock and timing requirements. RMII typically uses a 50MHz clock, while MII uses a 25MHz clock. Managing these different clock domains simultaneously would be complex and could lead to timing issues. The MDIO/MDC interface is used to configure and manage the PHY. If two MCUs are trying to control the same PHY, there could be conflicts in the configuration and management of the PHY registers.

Regards

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lb2 · ‎2024-07-16

Hello @STea,

I mis-spoke. Its not a PHY the two devices are wired to, its an ethernet switch.

One port is MII and other port is RMII. RMII port is wired to STM32.

Also, I don't have MDIO and MDC pins wired from STM32 to the switch. Would this cause any issues during initialazlization of LWIP.

I know the switch is working since resistor bootstrapping works and my other device over MII can communicate to the switch.

Thanks.

Pavel A. · ‎2024-07-16

> Also, I don't have MDIO and MDC pins wired from STM32 to the switch. Would this cause any issues during initialazlization of LWIP.

Of course, if the code still tries to read PHY state over MDIO there would be issues

STea · ‎2024-07-17

Hello @lb2 ,

indeed, this may cause problems and conflicting access during initialization over the MDIO/MDC channels.
Regards

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SofLit · ‎2024-11-27

Issue of RAM (the warning message related to 0x24000000 address) is fixed in v6.13.0.

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