LwIP TCP/IP with FreeRTOS

This application guides STM32Cube HAL API users to run LwIP TCP/IP stack with FreeRTOS by testing on Nucleo-F429ZI. I'm using STM32CubeMX code generator to test the LwIP TCP/IP stack + FreeRTOS and compile with AC6.

The example from repository STM32Cube_FW_F4_V1.18.0\Projects\STM32F429ZI-Nucleo\Applications\LwIP\LwIP_HTTP_Server_Netconn_RTOS is a good reference. It is working fine out-of-box, but however, if you are using STM32CubeMX to generate the code. You must be beware of the following tweak in order to it works with LAN8720a PHY transcevier.

Case 1

From STM32CubeMX, goto Configuration tab --> select ETH --> goto Parameter Setting. Now look at the PHY Address, by default it is set to 1, which is not the right. It is because RXER/PHYAD0 at LAN8720a is connected to Ground with a 10K resistor (kindly refer to Nucleo-F429ZI schematic). So therefore the PHY Address needs to set to 0.

Case 2

At ETH Configuration, goto Advanced Parameters tab --> goto Extended: External PHY Configuration. By refer to the LAN8720a datasheet,

PHY Special Control/Status Register = 31 (0xF1)

PHY Speed mask = 4 (0x0004) - means for 10MB/s and 100MB/s

PHY Duplex mask = 16 (0x0010)

PHY Interrupt Source Flag Register = 29 (0x1D)

PHY Link down inturrupt = 16 (0x10) - at Bits4

Case 3

Remember to increase your FreeRTOS stack size for example at StartDefaultTask

	osThreadDef( defaultTask, StartDefaultTask, osPriorityNormal, 0, 128*5 );
	

Or other wise, insufficient stack size will cause your board to hang

Special Note :

There is a retarget printf in this project where you can find at __io_putchar inside syscall.c. This retarget is used for UART3 which connected to ST-Link V2. To debug Lwip stack, please insert LWIP_DEBUG at Preprocessor in the AC6. In order to debug more detail error messages, please refer to opt.h and activate those error messages that you want. For example

	#define ICMP_DEBUG   LWIP_DBG_ON //LWIP_DBG_OFF