C++ 使用Serial.print()的millis()函数输出
这是密码C++ 使用Serial.print()的millis()函数输出,c++,arduino,embedded,C++,Arduino,Embedded,这是密码 void setup() { // put your setup code here, to run once: Serial.begin(9600); } void loop() { // put your main code here, to run repeatedly: Serial.println(millis()); } 这是输出 15:26:28.813->0 15:26:28.813->0 15:26:28.932->0 15:26:28.932
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
}
void loop() {
// put your main code here, to run repeatedly:
Serial.println(millis());
}
这是输出
15:26:28.813->0 15:26:28.813->0 15:26:28.932->0 15:26:28.932->
0 15:26:28.932 -> 0 15:26:28.932 -> 0 15:26:28.932 -> 0 15:26:28.932
-> 0 15:26:28.932 -> 0 15:26:28.932 -> 0 15:26:28.932 -> 0 15:26:28.932 -> 0 15:26:28.932 -> 0 15:26:28.932 -> 0 15:26:28.932 ->
0 15:26:28.932 -> 1 15:26:28.932 -> 1 15:26:28.932 -> 1 15:26:28.932
-> 1 15:26:28.932 -> 1 15:26:28.932 -> 1 15:26:28.932 -> 1 15:26:28.932 -> 4 15:26:28.932 -> 7 15:26:28.932 -> 10 15:26:28.932 ->
14 15:26:28.932 -> 18 15:26:28.932 -> 22 15:26:28.932 -> 26
15:26:28.932 -> 30 15:26:28.932 -> 34 15:26:28.932 -> 38 15:26:28.932
-> 43 15:26:28.932 -> 47 15:26:28.932 -> 51 15:26:28.932 -> 55 15:26:28.959 -> 59 15:26:28.959 -> 64 15:26:28.959 -> 68 15:26:28.959
-> 72 15:26:28.959 -> 76 15:26:28.959 -> 80 15:26:28.990 -> 84 15:26:28.990 -> 89 15:26:28.990 -> 93 15:26:28.990 -> 97 15:26:28.990
-> 101 15:26:28.990 -> 106 15:26:28.990 -> 111 15:26:29.029 -> 116 15:26:29.029 -> 121 15:26:29.029 -> 126 15:26:29.029 -> 133
15:26:29.029 -> 138 15:26:29.029 -> 143 15:26:29.029 -> 148
15:26:29.029 -> 153 15:26:29.064 -> 158 15:26:29.064 -> 163
15:26:29.064 -> 168 15:26:29.064 -> 174 15:26:29.064 -> 179
15:26:29.064 -> 184 15:26:29.064 -> 189 15:26:29.101 -> 195
15:26:29.101 -> 200 15:26:29.101 -> 205 15:26:29.101 -> 210
15:26:29.101 -> 216 15:26:29.101 -> 221 15:26:29.101 -> 226
15:26:29.136 -> 231 15:26:29.136 -> 236 15:26:29.136 -> 241
15:26:29.136 -> 246 15:26:29.136 -> 251 15:26:29.136 -> 257
15:26:29.136 -> 263 15:26:29.173 -> 268 15:26:29.173 -> 273
15:26:29.173 -> 278 15:26:29.173 -> 283 15:26:29.173 -> 288
15:26:29.173 -> 293 15:26:29.173 -> 299 15:26:29.210 -> 304
15:26:29.210 -> 309 15:26:29.210 -> 314 15:26:29.210 -> 319
15:26:29.210 -> 324 15:26:29.210 -> 330 15:26:29.210 -> 335
15:26:29.248 -> 340 15:26:29.248 -> 346 15:26:29.248 -> 351
15:26:29.248 -> 356 15:26:29.248 -> 361 15:26:29.248 -> 366
15:26:29.248 -> 371 15:26:29.284 -> 376 15:26:29.284 -> 381
15:26:29.284 -> 387 15:26:29.284 -> 392 15:26:29.284 -> 398
15:26:29.284 -> 403 15:26:29.284 -> 408 15:26:29.320 -> 413
15:26:29.320 -> 418 15:26:29.320 -> 423 15:26:29.320 -> 429
15:26:29.320 -> 434 15:26:29.320 -> 439 15:26:29.320 -> 444
15:26:29.354 -> 449 15:26:29.354 -> 454 15:26:29.354 -> 459
15:26:29.354 -> 465 15:26:29.354 -> 471 15:26:29.354 -> 476
15:26:29.387 -> 481 15:26:29.387 -> 486 15:26:29.387 -> 491
15:26:29.387 -> 496 15:26:29.387 -> 501 15:26:29.387 -> 506
15:26:29.387 -> 512 15:26:29.422 -> 517 15:26:29.422 -> 522
15:26:29.422 -> 528 15:26:29.422 -> 533 15:26:29.422 -> 538
15:26:29.422 -> 543 15:26:29.422 -> 548 15:26:29.456 -> 553
15:26:29.456 -> 559 15:26:29.456 -> 564 15:26:29.456 -> 569
15:26:29.456 -> 574 15:26:29.456 -> 579 15:26:29.492 -> 584
15:26:29.492 -> 589 15:26:29.492 -> 595 15:26:29.492 -> 601
15:26:29.492 -> 606 15:26:29.492 -> 611 15:26:29.492 -> 616
15:26:29.529 -> 621 15:26:29.529 -> 626 15:26:29.529 -> 631
15:26:29.529 -> 636 15:26:29.529 -> 642 15:26:29.529 -> 647
15:26:29.529 -> 652 15:26:29.567 -> 657 15:26:29.567 -> 663
15:26:29.567 -> 668 15:26:29.567 -> 673 15:26:29.567 -> 678
15:26:29.567 -> 684 15:26:29.567 -> 689 15:26:29.602 -> 694
15:26:29.602 -> 699 15:26:29.602 -> 704 15:26:29.602 -> 709
15:26:29.602 -> 714 15:26:29.602 -> 719 15:26:29.602 -> 724
15:26:29.638 -> 731 15:26:29.638 -> 736 15:26:29.638 -> 741
15:26:29.638 -> 746 15:26:29.638 -> 751 15:26:29.638 -> 756
15:26:29.638 -> 761 15:26:29.672 -> 766 15:26:29.672 -> 772
15:26:29.672 -> 777 15:26:29.672 -> 782 15:26:29.672 -> 787
15:26:29.672 -> 792 15:26:29.672 -> 798 15:26:29.706 -> 803
15:26:29.706 -> 808 15:26:29.706 -> 814 15:26:29.706 -> 819
15:26:29.706 -> 824 15:26:29.706 -> 829 15:26:29.742 -> 834
15:26:29.742 -> 839 15:26:29.742 -> 844 15:26:29.742 -> 849
15:26:29.742->855
我正在尝试开发一种算法,使用和不使用巨型阵列来存储三轴加速度数据,以计算在任一轴上行驶的距离。
这是我能从Arduino和Arduino那里得到的最准确的时间吗?
这个输出一点也不准确。
我用错了吗?
为什么在这些时间间隔之后会出现此定时输出?
我在哪里可以找到更多关于这个的信息
这是我能从Arduino和Arduino那里得到的最准确的时间吗
还有micros()
。请注意,精度不是分辨率
我用错了吗
没有
为什么在这些时间间隔之后会出现此定时输出
millis()
的输出只是放在内部缓冲区中。在伪代码中,它通常是这样工作的:
char internal_buffer[SOME_SIZE];
void Serial::println(SOME_TYPE stuff) {
if (internal_buffer_is_full()) {
// actively wait for at least space for stuff to place
internal_buffer_wait_for_space_for_stuff(stuff);
}
internal_buffer += stuff; // just add the data to internal buffer
if (!hardware::is_writing()) {
hardware::start_writing(internal_buffer); // writes __asynchronously__!
}
}
首先,它是缓冲的。然后,异步地将缓冲区写入输出,主线程继续其操作。当缓冲区已满时,主线程会主动等待缓冲区中至少有一些空间,然后再将要写入的数据放入缓冲区。预计您将看到短暂的“刷新”,其中缓冲的输出会稍微输出一点,然后继续缓冲
如果要刷新缓冲数据,有
Serial.flush()
。您的测试主要取决于USB串行通信的性能、粒度和不确定性定时,而不是毫秒()的精度-同时,定时由连接的PC机提供,该PC机不是实时系统,其自身的缓冲行为只会增加另一个变量
无论是millis()
还是micros()
都和主板上的时钟源一样精确,一个典型的晶体振荡器大约可以达到50ppm或0.005%,陶瓷谐振器大约可以达到0.5%,而一个典型的TCXO大约可以达到2ppm(0.0002%)
在调用这些函数之间执行的任何代码都需要时间,诸如输出到USB CDC/ACM串行并在PC上捕获的println()
等操作将特别不确定
如果您真的想确认精度,您应该使用更快的
void setup()
{
pinMode(2, OUTPUT);
}
void loop()
{
digitalWrite( 2, millis() & 1 ) ;
}