Please find attached a new NetworkInterface.c for STM32F4. It has implemented the zero-copy feature in both directions, and therefore it is more efficient and faster than its earlier version.

I would like to invite anyone interested to try it out. Be aware that it may not be as stable yet as the existing driver. I tested it with UDP/TCP/ICMP/etc, and also with iperf.

The following settings are recommended for this driver:

~~~ /* Add to your 'FreeRTOSIPConfig.h'. */ #define ipconfigZEROCOPYRXDRIVER 1 #define ipconfigZEROCOPYTXDRIVER 1 #define ipconfigETHERNETDRIVERFILTERS_PACKETS 1

/* Add/change to your stm32f4xx_hal_conf.h : */

#include "FreeRTOS.h"
#include "task.h"
#include "FreeRTOSIPConfig.h"

#define ETH_RX_BUF_SIZE            ( ipconfigNETWORK_MTU + 36 )/* buffer size for receive */
#define ETH_TX_BUF_SIZE            ( ipconfigNETWORK_MTU + 36 )/* buffer size for transmit */

~~~

By default, ETH_RX_BUF_SIZE / ETH_TX_BUF_SIZE are defined as ETH_MAX_PACKET_SIZE, which is hard-coded as 1536.

With a limited amount of RAM, it may be very profitable to reduce the value of ipconfigNETWORK_MTU to e.g. (1024+40). So let tha value of ETH_RX_BUF_SIZE / ETH_TX_BUF_SIZE depend on ipconfigNETWORK_MTU.

The new driver will also filter incoming packets. That can be important in networks with many UDP broadcasts. These packets should be filtered-out as soon as possible in order not to occupy resources.

The following CUBE/HAL functions won't be called any more:

HAL_ETH_DMATxDescListInit()
HAL_ETH_DMARxDescListInit()
HAL_ETH_TransmitFrame()
HAL_ETH_GetReceivedFrame()

For two reasons: they're not compatible with zero-copy, and/or the in-line implementation is faster.

The interface will now work for two types of PHY's: DP83848I ( found on STM324xG-EVAL ), and also LAN8720 ( found on STM32F4-DISCOVERY ).

I pressed on Post too soon, hadn't attached the driver yet. Here it is

As xNetworkInterfaceInitialise() had become quite large and therefore less readable, I've split up some code into separate functions:

~~~ /* Initialise TX-descriptors. */ prvDMATxDescListInit();

/* Initialise RX-descriptors. */
prvDMARxDescListInit();

~~~

This time I also I included the latest iperf3 module. I tested on a STM3240G-EVAL, using the following defines for iperf:

~~~ /* Some defines for iperf, optimised for speed. / / Put these in your 'FreeRTOSIPConfig.h' */ #define ipconfigIPERFDOESECHO_UDP 0

#define ipconfigIPERF_VERSION                   3
#define ipconfigIPERF_STACK_SIZE_IPERF_TASK     680
#define ipconfigIPERF_TX_BUFSIZE                ( 8 * ipconfigTCP_MSS )
#define ipconfigIPERF_TX_WINSIZE                ( 6 )
#define ipconfigIPERF_RX_BUFSIZE                ( 8 * ipconfigTCP_MSS )
#define ipconfigIPERF_RX_WINSIZE                ( 6 )

/* The iperf module declares a character buffer to store its send data. */
#define ipconfigIPERF_RECV_BUFFER_SIZE          ( 2 * ipconfigTCP_MSS )

~~~

The above parameters are optimised for speed.

The iperf driver can be started by calling vIPerfInstall() once after the network is up ( vApplicationIPNetworkEventHook() is called with eNetworkUp ).

Here is an example optimised for memory usage:

~~~ /* Defines for iperf, optimised for memory usage. */ #define ipconfigIPERFTXBUFSIZE ( 3 * ipconfigTCPMSS ) #define ipconfigIPERFTXWINSIZE ( 2 ) #define ipconfigIPERFRXBUFSIZE ( 3 * ipconfigTCPMSS ) #define ipconfigIPERFRXWINSIZE ( 2 ) ~~~

Today I re-tested the memcpy() mode: it still functions. Using zero-copy is especially profitable when the device is sending data.