Serial.print stops working after sleep(duration)?

[jack1728]

Hi,

I made some basic changes to timedWakeup.ino and I noticed that after sleeping for 1 second, the serial/usb are turned off and don't turn back on. When you run this, it should stop after the first loop and the print statements and blinking will stop. Anyway to get a full wakeup after PM.Sleep(1000)?

I am running the 2.02 version of the 101 library

#include <Power.h>

volatile int x = 0;
void setup() {
pinMode(LED_BUILTIN, OUTPUT);
Serial.begin(9600);
Serial.println("SEtup");
}

void loop() {
for(int i = 0; i < 5; i++)
{
digitalWrite(LED_BUILTIN, HIGH);
delay(500);
digitalWrite(LED_BUILTIN, LOW);
delay(500);
Serial.println("loop ");
Serial.println(i);
}
Serial.println("full loop ");
Serial.println(x);
x++;
Serial.flush();
PM.sleep(1000);
}

[bigdinotech]

@jack1728 you will lose all serial USB functionality once you sleep.

[jack1728]

Thanks,

Is there any plans for future functions that will allow you to recover serial USB functionality?

Jack

[bigdinotech]

@jack1728 right now no.

[gdescamps]

@bigdinotech thanks for your work! So in fact, in the case of a product, if we are using low power it will not be possible to update the firmware via USB? except by asking a more complex procedure to the user. Do you see a workaround for this ? Thanks

[bigdinotech]

@gdescamps if you are not replacing the bootloader then simply resetting the board will get to into dfu-mode where you can upload a new sketch.
Normally the IDE goes into dfu-mode when the USB Serial port baud rate i set to 1200 baud.
Since USB is not available, you will need to trigger the reset using a different event to get it into dfu-mode