4.2. FreeRTOS Platforms¶

The following table shows the currently supported FreeRTOS platforms.

Table 4.5 Supported FreeRTOS Platforms¶
OS	Version	CPU	Network Stack	Toolchain	Architecture PIL	Architecture PSL
FreeRTOS	10.0.0	ARMv7E-M	LWiP 2.0.0	GCC 10.3.1	armv7emleElfgcc10.3.1 armv7emleElfgcc10.3.1CERT	armv7emleElfgcc10.3.1-FreeRTOS10.0 armv7emleElfgcc10.3.1CERT-FreeRTOS10.0

4.2.1. 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 S32G-VNP-RDB2 as the reference hardware. This reference kit has a S32G274A processor with 3x Arm Cortex-M7 LS pairs and 8MB system RAM. For a full description, please refer to the microcontroller documentation here.

NXP provides a comprehensive software ecosystem for its S32G platform. For development on the M7 core, NXP offers the S32 Design Studio (S32DS)—a free, Eclipse-based integrated development environment (IDE) that supports the full S32G family. S32DS includes a GCC-based C/C++ compiler, GDB debugger integration, and tools for flashing and debugging the M7 core.

To simplify embedded software development, NXP provides the Real-Time Drivers (RTD) 4.0 package. RTD includes all necessary low-level drivers and middleware components to build applications for the M7 core on S32G platforms. It is fully compliant with AUTOSAR 4.x and integrates with FreeRTOS and other lightweight RTOS environments. RTI used the following versions of the different components:

RTD version V4.0.0
S32 Design Studio V3.6.0
FreeRTOS Kernel V10.4.6
lwIP version V2.0.0

4.2.2. 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.

#ifndef LWIP_OPTS_H
#define LWIP_OPTS_H

/**
* @page misra_violations MISRA-C:2012 violations
*
* @section [global]
* Violates MISRA 2012 Advisory Rule 2.5, Global macro not referenced.
* The global macro will be used in function call of the module.
*/

/* ---------- Application APIs ---------- */
#define NO_SYS                     0
#define LWIP_RAW                   1
#define LWIP_SOCKET                (NO_SYS==0)
#define LWIP_NETCONN               (NO_SYS==0)

/* ---------- ARP options ---------- */
#define LWIP_ARP                   1
#define ARP_TABLE_SIZE             10
#define ARP_QUEUEING               1

/* ---------- IP options ---------- */
#define LWIP_IPV6                  0

/* ---------- DHCP options ---------- */
/* Define LWIP_DHCP to 1 if you want DHCP configuration of interfaces */
#define LWIP_DHCP                  0
/* 1 if you want to do an ARP check on the offered address (recommended) */
#define DHCP_DOES_ARP_CHECK        (LWIP_DHCP)

/* ---------- AUTOIP options ---------- */
#define LWIP_AUTOIP                    0
#define LWIP_DHCP_AUTOIP_COOP          (LWIP_DHCP && LWIP_AUTOIP)
#define LWIP_DHCP_AUTOIP_COOP_TRIES    3

/* Define IP_FORWARD to 1 if you wish to have the ability to forward
   IP packets across network interfaces. If you are going to run lwIP
   on a device with only one network interface, define this to 0. */
#define IP_FORWARD                     0

/* IP reassembly and segmentation.These are orthogonal even
* if they both deal with IP fragments */
#define IP_REASSEMBLY                  1
#define IP_REASS_MAX_PBUFS             10
#define MEMP_NUM_REASSDATA             10
#define IP_FRAG                        1

/* ---------- IP options ---------- */
#define LWIP_IPV4                      1
#define ICMP_TTL                       255
#define LWIP_ICMP                      1
#define LWIP_IGMP                      1

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

/* Controls if TCP should queue segments that arrive out of
   order. Define to 0 if your device is low on memory. */
#define TCP_QUEUE_OOSEQ         0

/* TCP Maximum segment size. */
#define TCP_MSS                 1536

/* TCP sender buffer space (bytes). */
#define TCP_SND_BUF             TCP_MSS * 4

/* TCP sender buffer space (pbufs). This must be at least = 2 *
   TCP_SND_BUF/TCP_MSS for things to work. */
#define TCP_SND_QUEUELEN       (4 * TCP_SND_BUF/TCP_MSS)

/* TCP writable space (bytes). This must be less than or equal
   to TCP_SND_BUF. It is the amount of space which must be
   available in the tcp snd_buf for select to return writable */
#define TCP_SNDLOWAT           (TCP_SND_BUF/2)

/* TCP receive window. */
#define TCP_WND                 4096

/* Maximum number of retransmissions of data segments. */
#define TCP_MAXRTX              2

/* Maximum number of retransmissions of SYN segments. */
#define TCP_SYNMAXRTX           2

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

/* ---------- Memory options ---------- */
/* MEM_ALIGNMENT: should be set to the alignment of the CPU for which
   lwIP is compiled. 4 byte alignment -> define MEM_ALIGNMENT to 4, 2
   byte alignment -> define MEM_ALIGNMENT to 2. */
/* MSVC port: intel processors do not need 4-byte alignment,
   but are faster that way! */

/*!
 * @brief Custom memcpy function used to optimize and improve the lwip copy speed process.
 *
 * This function copies len characters from memory area src to memory area dest using 64 bit alignment.
 */
void memcpy_64(uint64_t *dst, uint64_t * src, unsigned int len);

/*!
 * @brief Custom memcpy function used to optimize and improve the lwip copy speed process.
 *
 * This function copies len characters from memory area src to memory area dest.
 */
void memcpy_custom(void *dst, const void * src, unsigned int len);

#define MEMCPY(dst,src,len)         memcpy(dst,src,len)

/* Memory alignment must match your architecture - for ARM Cortex M7, 8-byte alignment is required */
#define MEM_ALIGNMENT               8

/* MEM_SIZE: the size of the heap memory. If the application will send
a lot of data that needs to be copied, this should be set high. */
#define MEM_SIZE                    128*1024

/* MEMP_NUM_PBUF: the number of memp struct pbufs. If the application
   sends a lot of data out of ROM (or other static memory), this
   should be set high. */
#define MEMP_NUM_PBUF               8

/* MEMP_NUM_RAW_PCB: the number of UDP protocol control blocks. One
   per active RAW connection. */
#define MEMP_NUM_RAW_PCB            4

/* MEMP_NUM_UDP_PCB: the number of UDP protocol control blocks. One
   per active UDP connection. */
#define MEMP_NUM_UDP_PCB            4

/* MEMP_NUM_TCP_PCB: the number of simultaneously active TCP connections. */
#define MEMP_NUM_TCP_PCB            4

/* MEMP_NUM_TCP_PCB_LISTEN: the number of listening TCP connections. */
#define MEMP_NUM_TCP_PCB_LISTEN     4

/* MEMP_NUM_TCP_SEG: the number of simultaneously queued TCP segments.*/
#define MEMP_NUM_TCP_SEG            64

/* MEMP_NUM_SYS_TIMEOUT: the number of simultaneously active timeouts. */
#define MEMP_NUM_SYS_TIMEOUT        15

/* The following four are used only with the sequential API and can be
   set to 0 if the application only will use the raw API. */
/* MEMP_NUM_NETBUF: the number of struct netbufs. */
#define MEMP_NUM_NETBUF             16

/* MEMP_NUM_NETCONN: the number of struct netconns. */
#define MEMP_NUM_NETCONN            32

/* MEMP_NUM_TCPIP_MSG_*: the number of struct tcpip_msg, which is used
   for sequential API communication and incoming packets. Used in
   src/api/tcpip.c. */
#define MEMP_NUM_TCPIP_MSG_API      40  /* Increased from 20 */
#define MEMP_NUM_TCPIP_MSG_INPKT    30  /* Increased from 20 */

/* MEM_USE_POOLS==1: Use an alternative to malloc()
   To use this, MEMP_USE_CUSTOM_POOLS also has to be enabled. */
#define MEM_USE_POOLS               0
#define MEMP_USE_CUSTOM_POOLS       0

/* ---------- Pbuf options ---------- */
/* PBUF_POOL_SIZE: the number of buffers in the pbuf pool. */
#define PBUF_POOL_SIZE              32
#define PBUF_POOL_BUFSIZE           1536

/** SYS_LIGHTWEIGHT_PROT
* define SYS_LIGHTWEIGHT_PROT in lwipopts.h if you want inter-task protection
* for certain critical regions during buffer allocation, deallocation and memory
* allocation and deallocation. */
#define SYS_LIGHTWEIGHT_PROT        (NO_SYS==0)

/* ---------- Statistics options ---------- */
#define LWIP_STATS                      1
#define LWIP_STATS_DISPLAY              1

#if LWIP_STATS
#define LINK_STATS                      1
#define IP_STATS                        1
#define ICMP_STATS                      1
#define IGMP_STATS                      1
#define IPFRAG_STATS                    1
#define UDP_STATS                       1
#define TCP_STATS                       1
#define MEM_STATS                       1
#define MEMP_STATS                      1
#define PBUF_STATS                      1
#define SYS_STATS                       1
#endif /* LWIP_STATS */

/* ---------- PPP options ---------- */
#define PPP_SUPPORT                     0

/* ---------- Other options ---------- */

/* (LWIP_ETHERNET == 1) Enable ETHERNET support even though ARP might be disabled */
#define LWIP_ETHERNET                   1

#define TCPIP_MBOX_SIZE                 24

#define DEFAULT_UDP_RECVMBOX_SIZE       1500
#define DEFAULT_TCP_RECVMBOX_SIZE       1500
#define DEFAULT_RAW_RECVMBOX_SIZE       1500
#define DEFAULT_ACCEPTMBOX_SIZE         1500
#define LWIP_NETIF_TX_SINGLE_PBUF       1

#define LWIP_SUPPORT_CUSTOM_PBUF        1

#define LWIP_SNMP                       LWIP_UDP
#define MIB2_STATS                      LWIP_SNMP

#define LWIP_DNS                        LWIP_UDP
#define LWIP_MDNS_RESPONDER             LWIP_UDP

#define LWIP_NUM_NETIF_CLIENT_DATA      (LWIP_MDNS_RESPONDER)

#define LWIP_HAVE_LOOPIF                0
#define LWIP_NETIF_LOOPBACK             0

#define TCP_LISTEN_BACKLOG              1

#define LWIP_COMPAT_SOCKETS             1
#define LWIP_SO_RCVTIMEO                1
#define LWIP_SO_RCVBUF                  1

#define LWIP_TCPIP_CORE_LOCKING         1

#define LWIP_NETIF_LINK_CALLBACK        1
#define LWIP_NETIF_STATUS_CALLBACK      1

#define LWIP_NETCONN_SEM_PER_THREAD     0

#define LWIP_SOCKET_SET_ERRNO           1

#define LWIP_NETIF_HOSTNAME             1

/* ---------- TIMEVAL options ---------- */
#define LWIP_TIMEVAL_PRIVATE            0

/* ---------- Thread options ---------- */
#define TCPIP_THREAD_NAME               "tcpip_thread"
#define TCPIP_THREAD_STACKSIZE          1024*64
#define TCPIP_THREAD_PRIO               4
#define DEFAULT_THREAD_STACKSIZE        4096
#define DEFAULT_THREAD_PRIO             3

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

#define LWIP_SOCKET_SELECT              0

#endif /* LWIP_OPTS_H */

#ifndef FREERTOS_CONFIG_H
#define FREERTOS_CONFIG_H

/*-----------------------------------------------------------
 * Application specific definitions.
 *
 * These definitions should be adjusted for your particular hardware and
 * 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.
 *----------------------------------------------------------*/

#define configUSE_PREEMPTION                        1
#define configCPU_CLOCK_HZ                          ( 400000000UL )
#define configTICK_RATE_HZ                          ((TickType_t) 1000 )
#define configMAX_PRIORITIES                        10
#define configMINIMAL_STACK_SIZE                    RTI_configMINIMAL_STACK_SIZE
#define configMAX_TASK_NAME_LEN                     16
#define configUSE_16_BIT_TICKS                      0
#define configIDLE_SHOULD_YIELD                     1
#define configUSE_PREEMPTION                        1
#define configNUM_THREAD_LOCAL_STORAGE_POINTERS     2
#define configUSE_PORT_OPTIMISED_TASK_SELECTION     0
#define configUSE_TASK_NOTIFICATIONS                1
#define configUSE_TIME_SLICING                      0
#define configUSE_NEWLIB_REENTRANT                  0
#define configENABLE_BACKWARD_COMPATIBILITY         1
#define configUSE_POSIX_ERRNO                       0
#define configUSE_APPLICATION_TASK_TAG              0
#define configRECORD_STACK_HIGH_ADDRESS             1

/* Definition assert() function. */
#define configASSERT(x)                             if((x)==0) { taskDISABLE_INTERRUPTS(); __asm__ volatile ("bkpt #0"); for( ;; ); }

/* The highest interrupt priority that can be used by any interrupt service
routine that makes calls to interrupt safe FreeRTOS API functions.  DO NOT CALL
INTERRUPT SAFE FREERTOS API FUNCTIONS FROM ANY INTERRUPT THAT HAS A HIGHER
PRIORITY THAN THIS! (higher priorities are lower numeric values. */
#define configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY ( 2 )

/* Memory allocation related definitions. */
#define configSUPPORT_STATIC_ALLOCATION             0
#define configSUPPORT_DYNAMIC_ALLOCATION            1
#define configTOTAL_HEAP_SIZE                       (( size_t ) (__heap_size__) )
#define configAPPLICATION_ALLOCATED_HEAP            4

/* Hook function related definitions. */
#define configUSE_IDLE_HOOK                         0
#define configUSE_TICK_HOOK                         0
#define configUSE_MALLOC_FAILED_HOOK                1
#define configCHECK_FOR_STACK_OVERFLOW              1
#define configUSE_DAEMON_TASK_STARTUP_HOOK          0

/* Run time and task stats gathering related definitions. */
#define configGENERATE_RUN_TIME_STATS               1
#define portCONFIGURE_TIMER_FOR_RUN_TIME_STATS()
#define portGET_RUN_TIME_COUNTER_VALUE()            xTaskGetTickCount()
#define configUSE_TRACE_FACILITY                    1
#define configUSE_STATS_FORMATTING_FUNCTIONS        1

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

/* SEMAPHORES and MUTEXS */
#define configUSE_MUTEXES                           1
#define configUSE_RECURSIVE_MUTEXES                 1
#define configUSE_COUNTING_SEMAPHORES               1

/* Software timer related definitions. */
/* Software timer related definitions. */
#define configUSE_TIMERS                            1
#define configTIMER_TASK_PRIORITY                   6
#define configTIMER_QUEUE_LENGTH                    16
#define configTIMER_TASK_STACK_DEPTH                (1024*2)

/* Tickless Idle Mode */
#define configUSE_TICKLESS_IDLE                     0

/* QUEUE */
#define configQUEUE_REGISTRY_SIZE                   8
#define configUSE_QUEUE_SETS                        0

/* Optional functions - most linkers will remove unused functions anyway. */
#define INCLUDE_vTaskPrioritySet                    1
#define INCLUDE_uxTaskPriorityGet                   1
#define INCLUDE_vTaskDelete                         1
#define INCLUDE_vTaskSuspend                        1
#define INCLUDE_vTaskDelayUntil                     1
#define INCLUDE_vTaskDelay                          1
#define INCLUDE_xTaskGetSchedulerState              1
#define INCLUDE_xTaskGetCurrentTaskHandle           1
#define INCLUDE_uxTaskGetStackHighWaterMark         1
#define INCLUDE_uxTaskGetStackHighWaterMark2        0
#define INCLUDE_xTaskGetIdleTaskHandle              0
#define INCLUDE_eTaskGetState                       1
#define INCLUDE_xEventGroupSetBitFromISR            1
#define INCLUDE_xTimerPendFunctionCall              1
#define INCLUDE_xTaskAbortDelay                     1
#define INCLUDE_xTaskGetHandle                      1
#define INCLUDE_xTaskResumeFromISR                  1
#define INCLUDE_xQueueGetMutexHolder                1

/* Run time stats gathering definitions. */
#ifdef __GNUC__
    /* The #ifdef just prevents this C specific syntax from being included in
    assembly files. */
    void vMainConfigureTimerForRunTimeStats( void );
    unsigned long ulMainGetRunTimeCounterValue( void );
#endif

/* Cortex-M specific definitions. */
#ifdef __NVIC_PRIO_BITS
  #define configPRIO_BITS                         __NVIC_PRIO_BITS
#else
  #define configPRIO_BITS                         4
#endif

/* The lowest interrupt priority that can be used in a call to a "set priority"
function. */
#define configLIBRARY_LOWEST_INTERRUPT_PRIORITY  (0x0F)

/* Interrupt priorities used by the kernel port layer itself.  These are generic
to all Cortex-M ports, and do not rely on any particular library functions. */
#ifndef configKERNEL_INTERRUPT_PRIORITY
  #define configKERNEL_INTERRUPT_PRIORITY         (configLIBRARY_LOWEST_INTERRUPT_PRIORITY << (8-configPRIO_BITS))
#endif

/* !!!! configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to zero !!!!
See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html. */
#ifndef configMAX_SYSCALL_INTERRUPT_PRIORITY
  #define configMAX_SYSCALL_INTERRUPT_PRIORITY    (configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY << (8-configPRIO_BITS))
#endif

/* Definitions that map the FreeRTOS port interrupt handlers to their CMSIS
standard names. */
#define vPortSVCHandler                             SVC_Handler
#define xPortPendSVHandler                          PendSV_Handler
#define xPortSysTickHandler                         SysTick_Handler


#endif /* FREERTOS_CONFIG_H */

4.2.3. 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 4.6 PIL Compiler Flags for FreeRTOS Platforms¶
Architecture PIL	Library Format	Compiler Flags Used by RTI
armv7emleElfgcc10.3.1	Static Release	–specs=nosys.specs –specs=nano.specs -DOSAPI_CC_DEF_H=osapi/osapi_cc_gcc.h -DOSPSL_OS_DEF_H=rti_me_psl/ospsl/ospsl_os_stubs.h -DRTIME_TARGET_NAME=”armv7emleElfgcc10.3.1” -DRTI_PIL=1 -D__freertos__ -std=c99 -nostdinc -fstrict-aliasing -fsigned-char -O -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -fno-short-enums -DNDEBUG
	Static Debug	–specs=nosys.specs –specs=nano.specs -DOSAPI_CC_DEF_H=osapi/osapi_cc_gcc.h -DOSPSL_OS_DEF_H=rti_me_psl/ospsl/ospsl_os_stubs.h -DRTIME_TARGET_NAME=”armv7emleElfgcc10.3.1” -DRTI_PIL=1 -D__freertos__ -std=c99 -nostdinc -fstrict-aliasing -fsigned-char -O0 -g -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -fno-short-enums
armv7emleElfgcc10.3.1CERT	Static Release	–specs=nosys.specs –specs=nano.specs -DOSAPI_CC_DEF_H=osapi/osapi_cc_gcc.h -DOSPSL_OS_DEF_H=rti_me_psl/ospsl/ospsl_os_stubs.h -DRTIME_TARGET_NAME=”armv7emleElfgcc10.3.1CERT” -DRTI_CERT -DRTI_PIL=1 -D__freertos__ -std=c99 -nostdinc -fstrict-aliasing -fsigned-char -O -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -fno-short-enums -DNDEBUG
	Static Debug	-specs=nosys.specs –specs=nano.specs -DOSAPI_CC_DEF_H=osapi/osapi_cc_gcc.h -DOSPSL_OS_DEF_H=rti_me_psl/ospsl/ospsl_os_stubs.h -DRTIME_TARGET_NAME=”armv7emleElfgcc10.3.1CERT” -DRTI_CERT -DRTI_PIL=1 -D__freertos__ -std=c99 -nostdinc -fstrict-aliasing -fsigned-char -O0 -g -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -fno-short-enums

4.2.4. 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.

Make sure CMake is in the path.
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.
- LWIP_PORTS_PATH: Path to the lwIP ports folder that contains cc.h.
- RTD_PATH: Path to the folder that contains the eclipse plugins of RTD.
- 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.
Enter the following command:
```
RTIMEHOME/resource/scripts/rtime-make --target armv7emleElfgcc10.3.1-FreeRTOS10.0 \
                      -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.

The Connext Micro PSL is available in:

RTIMEHOME/lib/armv7emleElfgcc10.3.1-FreeRTOS10.0

4.2.5. 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 4.7 PSL Compiler Flags for FreeRTOS Platforms¶
Architecture PSL	Library Format	Compiler Flags Used by RTI
armv7emleElfgcc10.3.1-FreeRTOS10.0	Static Release	–specs=nosys.specs –specs=nano.specs -DNDEBUG -DOSAPI_CC_DEF_H=osapi/osapi_cc_gcc.h -DOSPSL_OS_DEF_H=rti_me_psl/ospsl/ospsl_os_freertos.h -DRTIME_TARGET_NAME=”armv7emleElfgcc10.3.1-FreeRTOS10.0” -DRTI_PSL=1 -DUSING_RTD=1 -D_TIMEVAL_DEFINED=0 -D__freertos__ -std=c99 -fstrict-aliasing -fsigned-char -O -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -fno-short-enums -DNDEBUG
	Static Debug	–specs=nosys.specs –specs=nano.specs -DOSAPI_CC_DEF_H=osapi/osapi_cc_gcc.h -DOSPSL_OS_DEF_H=rti_me_psl/ospsl/ospsl_os_freertos.h -DRTIME_TARGET_NAME=”armv7emleElfgcc10.3.1-FreeRTOS10.0” -DRTI_PSL=1 -DUSING_RTD=1 -D_TIMEVAL_DEFINED=0 -D__freertos__ -std=c99 -fstrict-aliasing -fsigned-char -O0 -g -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -fno-short-enums
armv7emleElfgcc10.3.1CERT-FreeRTOS10.0	Static Release	–specs=nosys.specs –specs=nano.specs -DNDEBUG -DOSAPI_CC_DEF_H=osapi/osapi_cc_gcc.h -DOSPSL_OS_DEF_H=rti_me_psl/ospsl/ospsl_os_freertos.h -DRTIME_TARGET_NAME=”armv7emleElfgcc10.3.1CERT-FreeRTOS10.0” -DRTI_CERT -DRTI_PSL=1 -DUSING_RTD=1 -D_TIMEVAL_DEFINED=0 -D__freertos__ -std=c99 -fstrict-aliasing -fsigned-char -O -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -fno-short-enums -DNDEBUG
	Static Debug	–specs=nosys.specs –specs=nano.specs -DOSAPI_CC_DEF_H=osapi/osapi_cc_gcc.h -DOSPSL_OS_DEF_H=rti_me_psl/ospsl/ospsl_os_freertos.h -DRTIME_TARGET_NAME=”armv7emleElfgcc10.3.1CERT-FreeRTOS10.0” -DRTI_CERT -DRTI_PSL=1 -DUSING_RTD=1 -D_TIMEVAL_DEFINED=0 -D__freertos__ -std=c99 -fstrict-aliasing -fsigned-char -O0 -g -mcpu=cortex-m7 -mthumb -mfpu=fpv5-sp-d16 -mfloat-abi=hard -ffunction-sections -fdata-sections -fno-short-enums

4.2.6. 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.