函数总是返回最大值"TIME_MAX“(或)0xFFFFFFF

Question

我正在开发微控制器TC23X (Infineon)，我的"time()“函数总是返回最大值0xFFFFFFF，我使用编译器”为TriCoreV6.3r1任务VX工具集“。

有谁能帮我解决上面的问题吗？所以time()返回自时代以来的时间(00:00:00 UTC，1970年1月1日)，以秒为单位

我尝试过这些方法"time(NULL)、time(0)和time(&Var)“。

Answer 1

由于时间/日期的可用性是特定于硬件平台的，所以time()作为一个默认实现提供，它只是返回“不可用”(-1)。

如果您的平台作为时间/日期源(如RTC、GNSS或NTP客户端)，则可以通过定义替换函数(例如：

time_t time( std::time_t *timeptr ) 
{
    time_t epoch_time  = 0 ;
    struct tm time_struct = {0} ;

    // Your code to get RTC data in a tm struct here
    ...
    struct tm timedate = {.tm_mday = ..., 
                          .tm_mon = ...,   // January == 0
                          .tm_year = ...,  // Years since 1900
                          .tm_hour = ...,
                          .tm_min = ...,
                          .tm_sec = ...
                         } ;

    // Convert tm struct to UNIX epoch time     
    epoch_time = std::mktime( &time_struct ) ;

    if( tp != 0 )
    {
        *timeptr = epoch_time ; 
    }

    return epoch_time ; 
}

一种更有效的方法是在第一次使用时用RTC源初始化1Hz周期计数器，然后返回计数器的值：

volatile static time_t epoch_time = TIME_MAX ;
void timer_ISR_1Hz( void )
{
    epoch_time++ ;
}

time_t time( std::time_t *timeptr ) 
{
    if( epoch_time == TIME_MAX )
    {
        struct tm time_struct = {0} ;
        
        // Your code to get RTC data in a tm struct here
        ...
        struct tm timedate = {.tm_mday = ..., 
                              .tm_mon = ...,   // January == 0
                              .tm_year = ...,  // Years since 1900
                              .tm_hour = ...,
                              .tm_min = ...,
                              .tm_sec = ...
                             } ;

        // Convert tm struct to UNIX epoch time     
        epoch_time = std::mktime( &time_struct ) ;

        // Start 1Hz timer here    
        ...
    }

    time_t t = epoch_time ;

    // Convert tm struct to UNIX epoch time     
    if( tp != 0 )
    {
        *timeptr = t ; 
    }

    return t ; 
}

以上解决方案工作，如果您没有RTC源，如果您初始化到时代时间，从用户提供的时间/日期输入后，开机。

当读取RTC硬件(或任何其他时间源)时，您需要确保时间是一致的；例如，可以读取59秒，就像它滚动到00秒一样，然后读取分钟，因此以20分59秒结束，而此时应该是19分59秒，或者20分00秒。这同样适用于分钟、小时、日、月和年的滚动.

您可能还希望通过GNSS 1 1PPS或NTP将第二次更新与UTC秒同步。这取决于您可能需要的精度级别。

Answer 2

尽管您有" AUTOSAR“标记集，但TC23x规范似乎只允许在它们上运行AUTOSAR。但是，在这个和汽车的例子中，我想知道为什么允许您使用time()函数。

首先，一个独立的环境必须支持的C标准的一部分，当然不包括时间。

其次，只有AUTOSAR自适应只支持非常小的POSIX子集，即POSIX profile PSE51 defined by IEEE1003.13。

但是如上所述，Adaptive并不是真正适合在这个TC23x上运行的东西。

因此，总的来说，我建议您，忘记所有C标准库函数的使用。查看AUTOSAR组件、它们的特性和接口。

也许您应该实际寻找AUTOSAR特性，比如StbM，以便首先支持同步的全局时基，然后通过车辆将其分发给您的ECU。

例如，必须配置StbM，就像SystemDescription中的AUTOSAR堆栈的其余部分一样(GlobalTimeDomains和TimeMaster/TimeSlave/TimeGateway)，以及对纯本地定时器(例如MCAL定时器)的引用，作为实际的本地时间库，即使还没有同步。

然后您可以使用这个StbM接口：

Std_ReturnType StbM_GetCurrentTime(
                      StbM_SynchronizedTimeBaseType timeBaseId,
                      StbM_TimeStampType* timeStamp,
                      StbM_UserDataType* userData)

/** Variables of this type are used for expressing time stamps including relative time and 
 * absolute calendar time.
 * The absolute time starts from 1970-01-01.   <----
 * 0 to 281474976710655s == 3257812230d [0xFFFF FFFF FFFF]
 * 0 to 999999999ns [0x3B9A C9FF]
 * invalid value in nanoseconds: [0x3B9A CA00] to [0x3FFF FFFF]
 * Bit 30 and 31 reserved, default: 0
 */
typedef struct {
    StbM_TimeBaseStatusType timeBaseStatus;
    uint32                  nanoSeconds;
    uint32                  seconds; // lower 32bit of 48bit seconds
    uint16                  secondsHi; // higher 16bit part of 48bit seconds 
} StbM_TimeStampType;

// There is also an "extended" version of the function and structure available
// using uint64 type instead the split uint32/uint16 for the seconds part

typedef uint8 StbM_TimeBaseStatusType;
// Bit 0 (LSB): 0x00: No Timeout on receiving Synchronisation Messages 
//              0x01: Timeout on receiving Synchronisation Messages
#define TIMEOUT 0x01
// Bit 2 0x00: Local Time Base is synchronous to Global Time Master
//       0x04: Local Time Base updates are based on a Time Gateway below the Global Time Master
#define SYNC_TO_GATEWAY 0x04
// Bit 3 0x00: Local Time Base is based on Local Time Base reference clock only (never synchronized with Global Time Base)
//       0x08: Local Time Base was at least synchronized with Global Time Base one time 
#define GLOBAL_TIME_BASE 0x08
// Bit 4 0x00: No leap into the future within the received time for Time Base
//       0x10: Leap into the future within the received time for Time Base exceeds a configured threshold 
#define TIMELEAP_FUTURE 0x10
// Bit 5 0x00: No leap into the past within the received time for Time Base 
//       0x20: Leap into the past within the received time for Time Base exceeds a configured threshold
#define TIMELEAP_PAST 0x20

就像这样：

const StbM_SynchronizedTimeBaseType timeBaseId = YOUR_TIME_DOMAIN_ID; // as configured in the AUTOSAR config tool

StbM_TimeStampType  timeStamp;
StbM_UserDataType   userData; // up to 3 bytes transmitted from TimeMaster (systemdependent)
Std_ReturnType ret;

SchM_Enter_ExclusiveArea_0();

ret = StbM_GetCurrentTimer(timeBaseId, &timeStamp, &userData);

SchM_Exit_ExclusiveArea_0();

if (ret == E_NOT_OK) {
    // Failure Handling and maybe report Error
    // Is StbM and AUTOSAR Stack ok and running?
    // Was this the correct timeBaseId?
} else {
    if (timeStamp.timeBaseStatus & TIMEOUT) {
       // TimeSync messages not received --> running further on local time (time since ECU was turned on)
    }
    if (timeStamp.timeBaseStatus & SYNC_TO_GATEWAY) {
        // Synced to gateway, but not the global time master --> synchronized to the gateways time
       // (possible drift from that gateway itself, or time since gateway was turned on)
    } else {
       // if bit is not set, we are synchronized to the global time master 
    }
    // ..
    // work with timeStamp.seconds and timeStamp.nanoSeconds 

如果没有StbM，或者没有同步时基，通常ECU只是在本地时间上运行，因为ECU在任何时候都是开放的。