MEPA Sample Application for LAN8840 EDS2 Daughterboard

• This sample application is a reference code for running a single 1G PHY on SAMA7. It uses the following hardware:

  • LAN8840 EDS2 Daughter Card (https://www.microchip.com/en-us/development-tool/ev12n54a)
  • SAMA7D65 Curiosity Kit (https://www.microchip.com/en-us/development-tool/ev63j76a)

• Softwares used:

  • mdio-tools (mdio.c) and MDIO-NETLINK kernel module (https://github.com/wkz/mdio-tools) for MDIO BUS Access.
  • MEPA code was referenced from repository https://github.com/MicrochipTech/mepa-app-malibu10-rpi.
  • v2025.12 sw-mepa (https://github.com/microchip-ung/sw-mepa)

• This is used as a starting point when developing own application. Used for sanity checking, example code includes simple IO test, simple mepa init, basic port information, and basic port polling.

• Reason for this example code: Use MEPA driver instead of Linux PHY driver.

• Note: This is not a production code! Please use only as a reference.

CMake Flags:

• -DCMAKE_TOOLCHAIN_FILE - part of Buildroot SDK or Yocto SDK.ls
  • Make sure to supply toolchainfile.cmake or *-toolchain.cmake otherwise it will build natively.

Test Setup

• LAN8840 PHY Daughterboard connected to SAMA7D65 Curiosity Kit EDS2 Connector.
• Make sure that mdio-netlink kernel module (part of wkz/mdio-tools) is installed in target platform.
  • In buildroot, it can be added in buildroot configuration. Or mdio-netlink can be built natively. (https://github.com/wkz/mdio-tools/tree/master/kernel)
• Make sure device tree overlay is added in BSP as follows.

&gmac1 {
    #address-cells = <1>;
    #size-cells = <0>;
    phy-mode = "rgmii-id";
    status = "okay";

    // Fix MAC at 1000Mbps
    fixed-link {
        speed = <1000>;
        full-duplex;
    };

    // Add mdio to appear in mdio-tools
    mdio {
        #address-cells = <1>;
        #size-cells = <0>;

        // Make sure disabled status of PHY connected to EDS2 to avoid loading drivers. 
        // In this case, PHYAD = 1 because of @1 & reg = <1>;
        ethernet-phy@1 {
            reg = <1>;
            status = "disabled";
        };
    };
};

Prepare Environment

1. Go to repository root directory
   • $ cd ./mepa-app-lan8840-sama7d65-eds2/
2. Initialize submodules if cloned.
   • $ git submodule init
   • $ git submodule update
3. The app was build on sw-mepa v2025.12 and uses mesa v2025.09
   • Check MESA version dependency of sw-mepa using:
     • $ cat ./sw-mepa/.cmake/deps-mesa.json
   • Clone required MESA version and place in ./sw-mepa/
     • $ git clone https://github.com/microchip-ung/mesa --branch=v2025.09 --depth=1 ./sw-mepa/sw-mesa/
4. [Optional] Download cross toolchain or skip this step if building natively.
   • Linux4Microchip cross toolchains (https://developerhelp.microchip.com/xwiki/bin/view/applications/linux4sam/components/softwaretools/)
   • Buildroot SDK - 2025.02 (Linux4SAM 2025.04) - SAMA7
     1. Download SDK
        • $ wget https://ww1.microchip.com/downloads/aemdocuments/documents/mpu32-direct/pub/demo/linux4sam-2025.04/linux4sam-buildroot-Cortex-A7-sdk-2025.04.tar.gz
     2. Extract somewhere. Make sure extract dir only has user rights. Example here is /opt/mchp/.
        • $ tar -xvf ./linux4sam-buildroot-Cortex-A7-sdk-2025.04.tar.gz -C /opt/mchp/
     3. Relocate SDK. Root rights NOT required.
        • $ /opt/mchp/arm-buildroot-linux-gnueabihf_sdk-buildroot/relocate-sdk.sh
   • Yocto Project 5.0.4 - scarthgap (Linux4Microchip 2025.04) - SAMA7 (NOT WORKING, See notes in build instructions for yocto)
     1. Download SDK
        • $ wget https://ww1.microchip.com/downloads/aemdocuments/documents/mpu32-direct/pub/demo/yocto-sdk/linux4sam-oecore-Cortex-A7-sdk-2025.04.sh
     2. Create folder somewhere to install yocto SDK toolchain. Example here is /opt/mchp/yocto-sdk-sama7/
        • $ mkdir /opt/mchp/yocto-sdk-sama7/
     3. Give execute command and run .sh.
        • $ chmod 775 ./linux4sam-oecore-Cortex-A7-sdk-2025.04.sh
        • $ ./linux4sam-oecore-Cortex-A7-sdk-2025.04.sh
     4. Make sure to set your install directory.

        Enter target directory for SDK (default: /usr/local/oecore-x86_64): /opt/mchp/yocto-sdk-sama7/
        You are about to install the SDK to "/opt/mchp/yocto-sdk-sama7". Proceed [Y/n]? Y
        

Build Instructions

1. Create a cmake build directory and change to it.
   • $ cd ./mepa-app-lan8840-sama7d65-eds2/
   • $ mkdir ./build/
   • $ cd ./build/
2. Create a CMake Project and make sure to add toolchain if cross compiling.
   • If using Buildroot SDK:
     • $ cmake ../mepa_app_sanity_check_standalone_lan884x/ -DCMAKE_TOOLCHAIN_FILE=$(find /opt/mchp/arm-buildroot-linux-gnueabihf_sdk-buildroot -name "toolchainfile.cmake")
     • Note: find command is used to easily find toolchainfile.cmake.
   • If using Yocto SDK:
     • $ cmake ../mepa_app_sanity_check_standalone_lan884x/ -DCMAKE_TOOLCHAIN_FILE=$(find /opt/mchp/yocto-sdk-sama7 -name "*-toolchain.cmake")
     • Note: This will fail since this app requires libmnl which is not part of Yocto SDK. Command was provided in case user has built their custom yocto SDK.
3. Run $ make

Expected Build Output

• See docs/build_log.txt; contains buildroot and yocto output.

Expected Application Output

• See docs/app_log.txt