Teensy 3.2 Serial Initialization problem again

[paynterf]

I have a very simple program to test a FIFO class, as follows:

/*
    Name:       FIFO_Class_Test.ino
    Created:	12/28/2019 12:51:15 PM
    Author:     FRANKNEWXPS15\Frank
*/

#include "FIFO_Class.h"
FIFO myFIFO(64);

void setup()
{
    Serial.begin(115200);
    unsigned long now = millis();
    int idx = 0;
    while (!Serial && (millis() - now) < 3000)
    {
        delay(100);
        idx++;
    }

    //delay(3000);
    Serial.printf("Serial port available after %lu mSec with idx = %d\n", millis() - now, idx);
}

void loop()
{
}

but the Serial port won't initialize reliably. With the code as shown below, it only properly initialized 6 our of 8 trials, as shown in the following printout

Opening port
Port failed to open
Port open
Serial port available after 1400 mSec with idx = 14
Port open
Serial port available after 1200 mSec with idx = 12
Port open
Serial port available after 2100 mSec with idx = 21
Port open
Port open
Serial port available after 700 mSec with idx = 7
Port open
Serial port available after 1600 mSec with idx = 16
Port open
Port open
Serial port available after 1500 mSec with idx = 15

The two failures are identified by the two instances of two 'Port open' lines back-to-back

What am I doing wrong here?

TIA,

Frank

 

[paynterf]

If I change the delay value inside the while() loop from 100 to 500, then the loop will reliably terminate with idx = 3. However, for lower delay values, the reliability goes down, until with delay(10) it will always hang forever.

 

[WMXZ]

try with very long timeouts, say 30000.
most likely, your terminal program or PC may be unreliable with connecting to Serial.

Alternatively, does FIFO_Class uses Serial?

 

[paynterf]

No, the FIFO class constructor does not use serial. Other member functions do use serial occasionally for debug, but only well after all of setup() has run.

Using a recent Win10 Dell XPS15 9750, and I don't have any problem with Arduino boards - just the Teensy.

Frank