5 years, 5 months ago.

Printed out string after woken up from deepsleep() are broken.

Hi,

I'm testing deepsleep() function on ST Nucleo-L152RE board. Here is my code.

simple deepsleep and wake up by button

#include "mbed.h"

Serial pc(SERIAL_TX, SERIAL_RX);
InterruptIn event(USER_BUTTON);
DigitalOut myled(LED1);

void trigger() {
    //wait(1);
    pc.printf("pressed\r\n");
}

int main() {
  int i = 1;
  pc.baud(9600);
  pc.printf("Hello World !\r\n");
  event.rise(&trigger);
  while(1) { 
      myled = !myled;
      pc.printf("Enter deepsleep!\r\n", i++);
      deepsleep();
      pc.printf("Woken up\r\n");
  }
}

And, here is result.

Result on terminal

Hello World !                                                                
Enter deepsleep!...............                                              
                               Woken up                                      
Enter deepsleep!

The 'pressed' string in trigger() function is broken. I found an article https://developer.mbed.org/questions/50532/Problems-after-WakeUp-from-deepsleep. So I commented out the printing in trigger().

Then, the result is ...

No printing pressed

Hello World !                                                
Enter deepsleep!C??k??.up                                   
Enter deepsleep!

Why is still the string broken?? Does the PLL need some time to be reconfigured? So I added wait(1.0) into trigger().

stuck...

Hello World !
Enter deepsleep!..

Isn't wait() NOP based simple delay()? I don't know why the code stucks.

So I moved wait(1.0) in trigger() to right after deepsleep().

still broken characters

Hello World !
Enter deepsleep!C?Woken up
Enter deepsleep!

In this case, the code doesn't stuck. But still broken characters are printed before 'Woken up' string.

Is there anybody know it? Thanks.

-Jongsoo

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