使用PIC32MZ的内核定时器测量经过的时间是多少

编译器是否将返回的值作为符号号来处理？如果是这样的话，那就可以解释了。当我使用了*CP0xGETSyCalt编程延迟时，我发现我必须使用带符号的数字，或者强制转换为无符号。



以下为原文

Is the compiler treating the return value from _CP0_GET_COUNT as a signed number? If so, that could explain it.

When I've programmed delays using _CP0_GET_COUNT, I've found that I have to either use signed numbers, or cast to unsigned.

尝试：问题是翻滚开始时间现在可以更大。注意这只给了你31位。我认为有一种方法可以给你32位。



以下为原文

try:
static uint32_t StartTime;static int32_t TimeUsed;(...)

StartTime = _CP0_GET_COUNT();

// My code's elapsed time to be measured.

TimeUsed = (int32_t)( _CP0_GET_COUNT() - StartTime);the issue is roll over start time can be bigger that now.
note this gives you only 31 bits.
I think there is a method that gives you 32bits

OP的原始代码对我来说是有效的。我把你的代码放到我的应用程序中，在稍后的一行中设置一个断点，并在使用的变量时间上徘徊，它表示0x000 000 0C。参见屏幕捕获。这是一个PIC32 MZ2048 EF与SysCLK＝198兆赫。StestTimes的值是0x013E3C54。请注意，我必须将StestTimeand时间定义为函数外的全局变量（静态UTI32 32 t），以允许我悬停在它们上面以获得值。（编辑）因此相应的I-间隔为12（198000000/2）或121 ns。



以下为原文

The OP's original code seems to work for me as is. I dropped your code into my app, set a breakpoint one line later and hovered over the variable TimeUsed and it says 0x0000000C. See screen capture. This is with a PIC32MZ2048EF with a SYSCLK = 198 MHz. The value of StartTime was 0x013E3C54.

Note that I had to define StartTime and TimeUsed as global variables (static uint32_t) outside of the function to allow me to hover over them to get the values.



(edit) So the corresponding time iinterval is 12/(198000000/2) or 121 ns.
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嗨，已经在很多PIC32 MX设备上使用了“核心定时器”，没有这样的问题，没有MZ的实际经验。使用XC32编译器的版本是什么？消息第1条中显示的代码对我来说似乎很好。如果消息在第4行中被应用，则在消息5、4中的建议与OP代码并不完全不同。在Myz中的几毫秒内可能会发生很多事情，确保StestTimes中的值没有被执行。另一个可能的错误是块内的一些代码，在系统协处理器CP0中删除“核心定时器”计数寄存器。在不需要这种动作的情况下，出现了坏的示例代码，清除了“核心定时器”寄存器。E代码，如果有任何''''.'''.''.''.''.'c'，''.'''.''.''.'c'0'，''.''.'''，''.'''.''.'c'0'，''.''.'，'''，''.'''，''.'''.'，''''.'''，''.'c'0'，''.''.'''，''.''.'，''.'c'0'，''.'''，''.



以下为原文

Hi,
Have used the 'core timer' a lot on several PIC32MX devices, with no such problem, no actual experience with MZ.
What version of XC32 compiler is used?

Code shown in message #1 seem good to me.
Suggestions in message #5, #4 are not really different from OP code,
if calculation inside the paranthesis is carried out first, before the cast is applied in #4.

A lot may happen during a few milliseconds in a MZ,
make sure that value in StartTime haven't been trashed in some way during the time elapsed.

Another possible error would be some code inside the block, trashing the 'core timer' Count register, in system coprocessor CP0.
There have been bad example code around, clearing the 'core timer' register, when such action is never needed.
Search the source code if there is any occurrence of '_CP0_SET_COUNT' or 'mtc0(9' or similar.

You may try with a cast on the macro _CP0_GET_COUNT()
static uint32_t StartTime, TimeUsed;
(...)
StartTime = (uint32_t)_CP0_GET_COUNT();
// My code's elapsed time to be measured.
TimeUsed = (uint32_t)_CP0_GET_COUNT() - StartTime;
I would be surprised if it made any difference.

Regards,
Mysil