6.2. FreeRTOS Platforms

The following table shows the currently supported FreeRTOS platforms.

Table 6.4 Supported FreeRTOS Platforms

OS	Version	CPU	Network Stack	Toolchain	Architecture PIL	Architecture PSL
FreeRTOS	9.0.0	ARMv7E-M	LWiP 2.0.0	GCC 7.3.1	armv7emleElfgcc7.3.1 armv7emleElfgcc7.3.1CERT	armv7emleElfgcc7.3.1-FreeRTOS9.0 armv7emleElfgcc7.3.1CERT-FreeRTOS9.0

6.2.1. Port overview

RTI ported Connext Micro to run on the FreeRTOS operating system with the lwIP protocol stack. This section contains some additional information on the hardware and software used.

RTI used STM32F769I-DISC0 as the reference hardware. This development kit has a STM32F769NIH6 microcontroller with 2 Mbytes of Flash memory and 512 Kbytes of RAM. For a full description, please refer to the microcontroller documentation here.

STMicroelectronics (ST) provides a toolchain called SW4STM32. SW4STM32 is a free multi-OS software environment based on Eclipse, which supports the full range of STM32 microcontrollers and associated boards. SW4STM32 includes the GCC C/C++ compiler, a GDB-based debugger, and an Eclipse-based IDE.

ST also provides STM32CubeF7. STM32CubeF7 gathers all the generic embedded software components required to develop an application on the STM32F7 microcontrollers in a single package.

STM32CubeF7 also includes many examples and demonstration applications. The example, LwIP_HTTP_Server_Socket_RTOS is particularly useful as a starting point, since it provides a working FreeRTOS + lwIP configuration.

RTI used the following versions of the different components:

• SW4STM32 version 2.1

• STM32Cube_FW_F7 version V1.7.0

• FreeRTOS version V9.0.0

• lwIP version V2.0.0

6.2.2. How to configure lwIP and FreeRTOS

RTI ported Connext Micro to FreeRTOS using the following lwIP and FreeRTOS configurations. These can be tuned according to your needs by modifying the examples below. Details about how to configure these third-party components can also be found in the FreeRTOS documentation and lwIP documentation.

lwIP

FreeRTOS

#ifndef __LWIPOPTS_H__
#define __LWIPOPTS_H__

#include <limits.h>

#define NO_SYS                  0

/* ---------- Memory options ---------- */
#define MEM_ALIGNMENT           4

#define MEM_SIZE                (50*1024)

#define MEMP_NUM_PBUF           10

#define MEMP_NUM_UDP_PCB        6

#define MEMP_NUM_TCP_PCB        10

#define MEMP_NUM_TCP_PCB_LISTEN 5

#define MEMP_NUM_TCP_SEG        8

#define MEMP_NUM_SYS_TIMEOUT    10


/* ---------- Pbuf options ---------- */
#define PBUF_POOL_SIZE          8

#define PBUF_POOL_BUFSIZE       1524

/* ---------- IPv4 options ---------- */
#define LWIP_IPV4                1

/* ---------- TCP options ---------- */
#define LWIP_TCP                1
#define TCP_TTL                 255

#define TCP_QUEUE_OOSEQ         0

#define TCP_MSS                 (1500 - 40)      /* TCP_MSS = (Ethernet MTU - IP header size - TCP header size) */

#define TCP_SND_BUF             (4*TCP_MSS)

#define TCP_SND_QUEUELEN        (2* TCP_SND_BUF/TCP_MSS)

#define TCP_WND                 (2*TCP_MSS)


/* ---------- ICMP options ---------- */
#define LWIP_ICMP               1


/* ---------- DHCP options ---------- */
#define LWIP_DHCP               1


/* ---------- UDP options ---------- */
#define LWIP_UDP                1
#define UDP_TTL                 255


/* ---------- Statistics options ---------- */
#define LWIP_STATS 0

/* ---------- link callback options ---------- */
#define LWIP_NETIF_LINK_CALLBACK        1

/*
   --------------------------------------
   ---------- Checksum options ----------
   --------------------------------------
*/

/*
The STM32F7xx allows computing and verifying checksums by hardware
*/
#define CHECKSUM_BY_HARDWARE


#ifdef CHECKSUM_BY_HARDWARE
/* CHECKSUM_GEN_IP==0: Generate checksums by hardware for outgoing IP packets.*/
#define CHECKSUM_GEN_IP                 0
/* CHECKSUM_GEN_UDP==0: Generate checksums by hardware for outgoing UDP packets.*/
#define CHECKSUM_GEN_UDP                0
/* CHECKSUM_GEN_TCP==0: Generate checksums by hardware for outgoing TCP packets.*/
#define CHECKSUM_GEN_TCP                0
/* CHECKSUM_CHECK_IP==0: Check checksums by hardware for incoming IP packets.*/
#define CHECKSUM_CHECK_IP               0
/* CHECKSUM_CHECK_UDP==0: Check checksums by hardware for incoming UDP packets.*/
#define CHECKSUM_CHECK_UDP              0
/* CHECKSUM_CHECK_TCP==0: Check checksums by hardware for incoming TCP packets.*/
#define CHECKSUM_CHECK_TCP              0
/* CHECKSUM_CHECK_ICMP==0: Check checksums by hardware for incoming ICMP packets.*/
#define CHECKSUM_GEN_ICMP               0
#else
/* CHECKSUM_GEN_IP==1: Generate checksums in software for outgoing IP packets.*/
#define CHECKSUM_GEN_IP                 1
/* CHECKSUM_GEN_UDP==1: Generate checksums in software for outgoing UDP packets.*/
#define CHECKSUM_GEN_UDP                1
/* CHECKSUM_GEN_TCP==1: Generate checksums in software for outgoing TCP packets.*/
#define CHECKSUM_GEN_TCP                1
/* CHECKSUM_CHECK_IP==1: Check checksums in software for incoming IP packets.*/
#define CHECKSUM_CHECK_IP               1
/* CHECKSUM_CHECK_UDP==1: Check checksums in software for incoming UDP packets.*/
#define CHECKSUM_CHECK_UDP              1
/* CHECKSUM_CHECK_TCP==1: Check checksums in software for incoming TCP packets.*/
#define CHECKSUM_CHECK_TCP              1
/* CHECKSUM_CHECK_ICMP==1: Check checksums by hardware for incoming ICMP packets.*/
#define CHECKSUM_GEN_ICMP               1
#endif


/*
   ----------------------------------------------
   ---------- Sequential layer options ----------
   ----------------------------------------------
*/
#define LWIP_NETCONN                    1

/*
   ------------------------------------
   ---------- Socket options ----------
   ------------------------------------
*/
#define LWIP_SOCKET                     1

/*
   ---------------------------------
   ---------- OS options ----------
   ---------------------------------
*/

#define TCPIP_THREAD_NAME              "TCP/IP"
#define TCPIP_THREAD_STACKSIZE          1000
#define TCPIP_MBOX_SIZE                 6
#define DEFAULT_UDP_RECVMBOX_SIZE       2000
#define DEFAULT_TCP_RECVMBOX_SIZE       2000
#define DEFAULT_ACCEPTMBOX_SIZE         2000
#define DEFAULT_THREAD_STACKSIZE        500
#define TCPIP_THREAD_PRIO               osPriorityHigh

/**
* LWIP_SO_RCVBUF==1: Enable SO_RCVBUF processing.
*/
#define LWIP_SO_RCVBUF                  1


/**
* Instruct lwIP to use the errno provided by libc instead of the errno in lwIP.
* If your libc doesn't include errno, you might need to delete these macros.
*/
#undef LWIP_PROVIDE_ERRNO
#define LWIP_ERRNO_INCLUDE "errno.h"

#endif /* __LWIPOPTS_H__ */

#ifndef FREERTOS_CONFIG_H
#define FREERTOS_CONFIG_H

/*-----------------------------------------------------------
* Application specific definitions.
*
* These definitions should be adjusted for your application requirements.
*
* THESE PARAMETERS ARE DESCRIBED WITHIN THE 'CONFIGURATION' SECTION OF THE
* FreeRTOS API DOCUMENTATION AVAILABLE ON THE FreeRTOS.org WEB SITE.
*
* See http://www.freertos.org/a00110.html.
*----------------------------------------------------------*/

/* Ensure stdint is only used by the compiler, and not the assembler. */
#if defined(__ICCARM__) || defined(__CC_ARM) || defined(__GNUC__)
#include <stdint.h>
extern uint32_t SystemCoreClock;
#endif

#define configUSE_PREEMPTION              1
#define configUSE_IDLE_HOOK               0
#define configUSE_TICK_HOOK               0
#define configCPU_CLOCK_HZ                (SystemCoreClock)
#define configTICK_RATE_HZ                ((TickType_t)1000)
#define configMAX_PRIORITIES              (7)
#define configMINIMAL_STACK_SIZE          ((uint16_t)128)
#define configTOTAL_HEAP_SIZE             ((size_t)(400 * 1024))
#define configMAX_TASK_NAME_LEN           (16)
#define configUSE_TRACE_FACILITY          1
#define configUSE_16_BIT_TICKS            0
#define configIDLE_SHOULD_YIELD           1
#define configUSE_MUTEXES                 1
#define configQUEUE_REGISTRY_SIZE         8
#define configCHECK_FOR_STACK_OVERFLOW    0
#define configUSE_RECURSIVE_MUTEXES       1
#define configUSE_MALLOC_FAILED_HOOK      0
#define configUSE_APPLICATION_TASK_TAG    0
#define configUSE_COUNTING_SEMAPHORES     1
#define configGENERATE_RUN_TIME_STATS     0

/* Co-routine definitions. */
#define configUSE_CO_ROUTINES           0
#define configMAX_CO_ROUTINE_PRIORITIES (2)

/* Software timer definitions. */
#define configUSE_TIMERS             1
#define configTIMER_TASK_PRIORITY    (2)
#define configTIMER_QUEUE_LENGTH     10
#define configTIMER_TASK_STACK_DEPTH 1280

/* Set the following definitions to 1 to include the API function, or zero
to exclude the API function. */
#define INCLUDE_vTaskPrioritySet       1
#define INCLUDE_uxTaskPriorityGet      1
#define INCLUDE_vTaskDelete            1
#define INCLUDE_vTaskCleanUpResources  0
#define INCLUDE_vTaskSuspend           1
#define INCLUDE_vTaskDelayUntil        0
#define INCLUDE_vTaskDelay             1
#define INCLUDE_xTaskGetSchedulerState 1

/* Cortex-M specific definitions. */
#ifdef __NVIC_PRIO_BITS
/* __BVIC_PRIO_BITS will be specified when CMSIS is being used. */
#define configPRIO_BITS         __NVIC_PRIO_BITS
#else
#define configPRIO_BITS         4        /* 15 priority levels */
#endif

#define configLIBRARY_LOWEST_INTERRUPT_PRIORITY   0xf

#define configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY 5

#define configKERNEL_INTERRUPT_PRIORITY   ( configLIBRARY_LOWEST_INTERRUPT_PRIORITY << (8 - configPRIO_BITS) )

#define configMAX_SYSCALL_INTERRUPT_PRIORITY  ( configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY << (8 - configPRIO_BITS) )

#define configASSERT( x ) if( ( x ) == 0 ) { taskDISABLE_INTERRUPTS(); for( ;; ); }

#define vPortSVCHandler    SVC_Handler
#define xPortPendSVHandler PendSV_Handler

#endif /* FREERTOS_CONFIG_H */

6.2.3. How the PIL was built for FreeRTOS

This section describes how RTI built the Platform Independent Library (PIL) for FreeRTOS.

The following table shows the compiler flags RTI used to create the PIL for FreeRTOS platforms:

Table 6.5 PIL Compiler Flags for FreeRTOS Platforms

Architecture PIL	Library Format	Compiler Flags Used by RTI
armv7emleElfgcc7.3.1	Static Release	-std=c99 -Winit-self -fstrict-aliasing -Wmissing-declarations -Wall -Wextra -Wpedantic -Wshadow -Wcast-align -Wunused -Wconversion -Wsign-conversion -Wlogical-op -Wdouble-promotion -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -DNDEBUG -O -DRTI_PIL=1
	Static Debug	-std=c99 -Winit-self -fstrict-aliasing -Wmissing-declarations -Wall -Wextra -Wpedantic -Wshadow -Wcast-align -Wunused -Wconversion -Wsign-conversion -Wlogical-op -Wdouble-promotion -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -O0 -g -DRTI_PIL=1
armv7emleElfgcc7.3.1CERT	Static Release	-DRTI_CERT -std=c99 -Winit-self -fstrict-aliasing -Wmissing-declarations -Wall -Wextra -Wpedantic -Wshadow -Wcast-align -Wunused -Wconversion -Wsign-conversion -Wlogical-op -Wdouble-promotion -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -DNDEBUG -O -DRTI_PIL=1
	Static Debug	-DRTI_CERT -std=c99 -Winit-self -fstrict-aliasing -Wmissing-declarations -Wall -Wextra -Wpedantic -Wshadow -Wcast-align -Wunused -Wconversion -Wsign-conversion -Wlogical-op -Wdouble-promotion -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -O0 -g -DRTI_PIL=1

6.2.4. Building the PSL from source for FreeRTOS platforms

This section describes how to build your own PSL for FreeRTOS.

Connext Micro includes support to compile Platform Support Libraries (PSL) for FreeRTOS using CMake. Refer to Setting up the build environment before continuing with the following instructions.

1. Make sure CMake is in the path.

2. Define the following environment variables:

   • CONFIG_PATH: Path to where the FreeRTOSConfig.h and lwipopts.h files are located.

   • FREERTOS_PATH: Path to the FreeRTOS source code and header files.

   • LWIP_PATH: Path to the lwIP source code and header files.

   • PATH: Update your path with the location of the C and C++ compiler. By default, arm-none-eabi-gcc and arm-none-eabi-g++ are used as C and C++ compilers.

3. Enter the following command:

   RTIMEHOME/resource/scripts/rtime-make --target armv7emleElfgcc7.3.1-FreeRTOS9.0 \
                         -G "Unix Makefiles" --build
   

   Note

   rtime-make uses the architecture specified with --target to determine a few settings needed by Connext Micro. Please refer to Preparing to build for details.

4. The Connext Micro PSL is available in:

   RTIMEHOME/lib/armv7emleElfgcc7.3.1-FreeRTOS9.0
   

6.2.5. Building FreeRTOS applications with Connext Micro

This section describes how RTI built the Platform Support Library (PSL) for FreeRTOS platforms. You must build applications with compatible flags to the PIL and PSL in order to operate with Connext Micro. The PSL must also be binary compatible with the PIL. Applications must not specify the RTI_PSL or RTI_PIL preprocessor definitions.

The following table shows the compiler flags and required options that RTI used to build the PSL for FreeRTOS platforms. When you build the PSL with rtime-make, the --target argument automatically adds all the necessary flags for the specified architecture.

Table 6.6 PSL Compiler Flags for FreeRTOS Platforms

Architecture PSL	Library Format	Compiler Flags Used by RTI
armv7emleElfgcc7.3.1-FreeRTOS9.0	Static Release	-std=c99 -Winit-self -fstrict-aliasing -Wmissing-declarations -Wall -Wextra -Wpedantic -Wshadow -Wcast-align -Wunused -Wconversion -Wsign-conversion -Wlogical-op -Wdouble-promotion -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -DNDEBUG -O -DRTI_PSL=1
	Static Debug	-std=c99 -Winit-self -fstrict-aliasing -Wmissing-declarations -Wall -Wextra -Wpedantic -Wshadow -Wcast-align -Wunused -Wconversion -Wsign-conversion -Wlogical-op -Wdouble-promotion -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -O0 -g -DRTI_PSL=1
armv7emleElfgcc7.3.1CERT-FreeRTOS9.0	Static Release	-DRTI_CERT -std=c99 -Winit-self -fstrict-aliasing -Wmissing-declarations -Wall -Wextra -Wpedantic -Wshadow -Wcast-align -Wunused -Wconversion -Wsign-conversion -Wlogical-op -Wdouble-promotion -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -DNDEBUG -O -DRTI_PSL=1
	Static Debug	-DRTI_CERT -std=c99 -Winit-self -fstrict-aliasing -Wmissing-declarations -Wall -Wextra -Wpedantic -Wshadow -Wcast-align -Wunused -Wconversion -Wsign-conversion -Wlogical-op -Wdouble-promotion -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -O0 -g -DRTI_PSL=1

6.2.6. System tick rollovers

The OMG standard does not specify how an implementation of DDS should handle counter rollover. By default, Connext Micro does not check for rollover of the system tick count on FreeRTOS platforms.

The OSAPI_SystemFreeRTOS_get_time function uses the system tick count to calculate the time in milliseconds since the system started. It does so by multiplying the number of ticks since the system started by the FreeRTOS-defined constant portTICK_RATE_MS. Connext Micro stores the result in an unsigned 32-bit variable.

Two conditions can result from this calculation: the tick count can rollover, and the resulting calculation can be greater than the size of an unsigned int (2^32). This can cause an overflow, which would result in time appearing to go backwards.

If you need to change or mitigate this behavior, you can alter the source code for the reference implementation of OSAPI_SystemFreeRTOS_get_time (or provide your own implementation) and rebuild the PSL.