我正在为我的stm32f429板编写嵌入式操作系统的代码。我正在测试这段代码的经过时间:
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <time.h>
#include <stdint.h>
#define DEFAULT_DELAY 1
uint32_t m_nStart; //DEBUG Stopwatch start cycle counter value
uint32_t m_nStop; //DEBUG Stopwatch stop cycle counter value
#define DEMCR_TRCENA 0x01000000
/* Core Debug registers */
#define DEMCR (*((volatile uint32_t *)0xE000EDFC))
#define DWT_CTRL (*(volatile uint32_t *)0xE0001000)
#define CYCCNTENA (1<<0)
#define DWT_CYCCNT ((volatile uint32_t *)0xE0001004)
#define CPU_CYCLES *DWT_CYCCNT
#define STOPWATCH_START { m_nStart = *(*(volatile unsigned int*)0xE0001004);}//DWT_CYCCNT;}
#define STOPWATCH_STOP { m_nStop = *(*(volatile unsigned int *)0xE0001004);}
static inline void stopwatch_reset(void)
{
/* Enable DWT */
DEMCR |= DEMCR_TRCENA;
*DWT_CYCCNT = 0;
/* Enable CPU cycle counter */
DWT_CTRL |= CYCCNTENA;
}
static inline uint32_t stopwatch_getticks()
{
return CPU_CYCLES;
}
static inline void stopwatch_delay(uint32_t ticks)
{
stopwatch_reset();
while(1)
{
if (stopwatch_getticks() >= ticks)
break;
}
}
uint32_t CalcNanosecondsFromStopwatch(uint32_t nStart, uint32_t nStop)
{
uint32_t nTemp;
uint32_t n;
uint32_t SystemCoreClock = 180000000;
nTemp = nStop - nStart;
nTemp *= 1000; // Scale cycles by 1000.
n = SystemCoreClock / 1000000; // Convert Hz to MHz
nTemp = nTemp / n; // nanosec = (Cycles * 1000) / (Cycles/microsec)
return nTemp;
}
int main( int argc, char **argv )
{
int delay = DEFAULT_DELAY; // Initial value for the delay
int timeDiff = 0;
STOPWATCH_START;
printf("Trynn");
STOPWATCH_STOP;
timeDiff = CalcNanosecondsFromStopwatch(m_nStart, m_nStop);
printf("My function took %d nanosecondsn", timeDiff);
return( 0 );
}
它编译时没有错误,但是当我在stm32f429上运行该程序时,我得到了SEGV错误,可能是在 #define STOPWATCH_START 中。也许我在寄存器上有问题(?
代码 http://pastebin.com/qr6sF9eU(它删除了对我使用的系统调用的调用)
make 的输出为:http://pastebin.com/Q14xTaXH
当我在stm32f429板上运行测试时,输出为:http://pastebin.com/sGmjZjxj
你可以帮我吗?
NVIC 寄存器很可能受 MPU 保护,用户代码无法访问。使用操作系统时,您不能弄乱所有内容。
在#define
中获取SEGV
,因为#define
是预处理器指令,不构成输出的一部分。它可能在 #define 生成的代码中。您是否故意从0xE0001004
中读取地址,将该地址的内容读取为另一个地址,然后读取该地址的内容?这听起来不太可能是操作时钟的一种方式。
STOPWATCH_START;
和STOPWATCH_STOP;
的宏导致编译器出现"非法间接"错误。双指针引用导致读取的计数器值用作指针。
#define STOPWATCH_START { m_nStart = *(*(volatile unsigned int*)0xE0001004);}
#define STOPWATCH_STOP { m_nStop = *(*(volatile unsigned int *)0xE0001004);}
根据您的其他#define
声明和其中的地址,这些应该是
#define STOPWATCH_START { m_nStart = CPU_CYCLES;}
#define STOPWATCH_STOP { m_nStop = CPU_CYCLES;}
正如您在代码中的其他地方使用的那样?