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pico高级API函数中，
multicore_fifo_pop_timeout_us 和  multicore_fifo_push_timeout_us 的延时参数，
如修改为500微秒以上时，其延时似乎远远超过设定值，其反馈速度似乎被主核的交互所左右 ，而修改为200以下时，反馈出现阶越：运行这两个函数 的core1的打印速度快速增加，显示其延时更加与设定值相符。

测试的代码：

#include <stdio.h>
#include "pico/stdlib.h"#include "pico/multicore.h"
#define FLAG_VALUE 2void core1_entry() {uint32_t g=0;
bool ifthereisp=false;
uint64_t timeout_u=500;   //这儿修改为500微秒以上时，core1的打印速度和core0 1hz基本同步 ，而修改为200以下时，反馈出现阶越：core1的打印速度快速增加。
uint32_t out;lable2:multicore_fifo_push_timeout_us ( FLAG_VALUE,timeout_u) ;if( !multicore_fifo_pop_timeout_us (timeout_u,&out) )printf("Hmm, that's not right on core 1!\n");elseprintf("Its all gone well on core 1! %u  \n",out);
goto lable2;while (1)tight_loop_contents();
}int main() {stdio_init_all();sleep_ms(1000);
printf("Hello, fakeone\n");sleep_ms(1000);multicore_launch_core1(core1_entry);uint32_t g=0;// Wait for it to start up
lable:g = multicore_fifo_pop_blocking();if (g != FLAG_VALUE)printf("Hmm, that's not right on core 0!\n");else {multicore_fifo_push_blocking(FLAG_VALUE);printf("It's all gone well on core 0!\n");}
sleep_ms(1000);
goto lable;while (true) {printf("Hello, world!\n");sleep_ms(1000);}return 0;
}

关键函数介绍官方原文：

bool multicore_fifo_pop_timeout_us     (     uint64_t      timeout_us,
        uint32_t *      out
    )         

Pop data from the read FIFO (data from the other core) with timeout.

This function will block until there is data ready to be read or the timeout is reached

See the note in the fifo section for considerations regarding use of the inter-core FIFOs
Parameters

timeout_us     the timeout in microseconds
out     the location to store the popped data if available
Returns

true if the data was popped and a value copied into out, false if the timeout occurred before data could be popped

bool multicore_fifo_push_timeout_us     (     uint32_t      data,
        uint64_t      timeout_us
    )         

Push data on to the write FIFO (data to the other core) with timeout.

This function will block until there is space for the data to be sent or the timeout is reached
Parameters

data     A 32 bit value to push on to the FIFO
timeout_us     the timeout in microseconds
Returns

true if the data was pushed, false if the timeout occurred before data could be pushed

附pico例程原代码：

#include <stdio.h>
#include "pico/stdlib.h"
#include "pico/multicore.h"#define FLAG_VALUE 123void core1_entry() {multicore_fifo_push_blocking(FLAG_VALUE);uint32_t g = multicore_fifo_pop_blocking();if (g != FLAG_VALUE)printf("Hmm, that's not right on core 1!\n");elseprintf("Its all gone well on core 1!");while (1)tight_loop_contents();
}int main() {stdio_init_all();printf("Hello, multicore!\n");multicore_launch_core1(core1_entry);// Wait for it to start upuint32_t g = multicore_fifo_pop_blocking();if (g != FLAG_VALUE)printf("Hmm, that's not right on core 0!\n");else {multicore_fifo_push_blocking(FLAG_VALUE);printf("It's all gone well on core 0!");}}