stm32/boards/STM32F7DISC: Enable lwIP and Ethernet peripheral.

ports/stm32/boards/STM32F7DISC/mpconfigboard.h

 #define MICROPY_HW_BOARD_NAME       "F7DISC"
 #define MICROPY_HW_MCU_NAME         "STM32F746"
 
+#define MICROPY_PY_LWIP             (1)
+
 #define MICROPY_HW_HAS_SWITCH       (1)
 #define MICROPY_HW_HAS_FLASH        (1)
 #define MICROPY_HW_HAS_SDCARD       (1)
@@ -81,6 +83,18 @@ void STM32F7DISC_board_early_init(void);
 /*#define MICROPY_HW_USB_VBUS_DETECT_PIN (pin_J12)*/
 #define MICROPY_HW_USB_OTG_ID_PIN      (pin_A10)
 
+// Ethernet via RMII
+#define MICROPY_HW_ETH_MDC          (pin_C1)
+#define MICROPY_HW_ETH_MDIO         (pin_A2)
+#define MICROPY_HW_ETH_RMII_REF_CLK (pin_A1)
+#define MICROPY_HW_ETH_RMII_CRS_DV  (pin_A7)
+#define MICROPY_HW_ETH_RMII_RXD0    (pin_C4)
+#define MICROPY_HW_ETH_RMII_RXD1    (pin_C5)
+#define MICROPY_HW_ETH_RMII_RXER    (pin_G2)
+#define MICROPY_HW_ETH_RMII_TX_EN   (pin_G11)
+#define MICROPY_HW_ETH_RMII_TXD0    (pin_G13)
+#define MICROPY_HW_ETH_RMII_TXD1    (pin_G14)
+
 // SDRAM
 #define MICROPY_HW_SDRAM_SIZE  (64 / 8 * 1024 * 1024)  // 64 Mbit
 #define MICROPY_HW_SDRAM_STARTUP_TEST             (1)

ports/stm32/boards/STM32F7DISC/pins.csv

@@ -53,6 +53,16 @@ VCP_TX,PA9
 VCP_RX,PB7
 CAN_TX,PB13
 CAN_RX,PB12
+ETH_MDC,PC1
+ETH_MDIO,PA2
+ETH_RMII_REF_CLK,PA1
+ETH_RMII_CRS_DV,PA7
+ETH_RMII_RXD0,PC4
+ETH_RMII_RXD1,PC5
+ETH_RMII_RXER,PG2
+ETH_RMII_TX_EN,PG11
+ETH_RMII_TXD0,PG13
+ETH_RMII_TXD1,PG14
 SDRAM_SDCKE0,PC3
 SDRAM_SDNE0,PH3
 SDRAM_SDCLK,PG8