General bug: initialization and print issues when first connects to USB

[ElectricRCAircraftGuy]

There is some sort of initialization bug preventing prints, or reading the LED states, or anything like it, from properly working when you first connect to USB.

Related issue: #12

Here is some sample code to duplicate the issue:

#include <TrinketHidCombo.h>
#include <TrinketHidComboC.h>

void setup()
{
  TrinketHidCombo.begin();  
  
  TrinketHidCompatibleDelay(0); //increase to 2000 to remove the print errors entirely; decrease to 0 to make the errors worse and more frequent; use 1000 to cause occasional initial print errors only
  
  //wait until connected to USB before continuing
  //-note that isConnected() will change to true at that point 
  unsigned long counter = 0;
  while (TrinketHidCombo.isConnected() == false)
  {
    counter++;
    TrinketHidCombo.poll(); //The poll function must be called at least once every 10 ms, or you must command a keystroke. Otherwise, the computer may think that the device has stopped working, and give errors.
  }
  
  TrinketHidCombo.print(F("counter = ")); TrinketHidCombo.print(counter); //DOESN'T PRINT QUITE RIGHT!
  TrinketHidCombo.print(F("; t_ms = ")); TrinketHidCombo.println(millis());  
}

void loop()
{

}

//--------------------------------------------------------------------------------------------
//TrinketHidCompatibleDelay
//-this is a USB-compatible delay, so that the 10ms max time between poll calls is not exceeded
//--------------------------------------------------------------------------------------------
void TrinketHidCompatibleDelay(unsigned int desiredDelay_ms)
{
  unsigned long t_start = millis(); //ms
  while (millis()-t_start<desiredDelay_ms)
  {
    TrinketHidCombo.poll(); //keep the HID USB connection to the computer alive 
  }
}

Sample output, when printing into Notepad (NOT Notepad++, whose autocomplete messes with the output).

Using TrinketHidCompatibleDelay(0) at the beginning of setup():
(notice how messed up it is)
-note: each line below is after a new power reset of the microcontroller (unplug it from USB, then plug it back in)

unter = 41584; t_ms = 596
unter = 40789; t_ms = 590
unter = 42898; t_ms = 601
er = 42847; t_ms = 600
unter = 41137; t_ms = 594
nter = 40832; t_ms = 587
ounter = 41924; t_ms = 599
ter = 180498; t_ms = 1224
nter = 179296; t_ms = 1211
er = 41012; t_ms = 590
nter = 42755; t_ms = 602
er = 182202; t_ms = 1224

Using TrinketHidCompatibleDelay(1000) at the beginning of setup():
(only one erroneous print now)
-note: each line below is after a new power reset of the microcontroller (unplug it from USB, then plug it back in)

counter = 0; t_ms = 1307
counter = 0; t_ms = 1305
counter = 0; t_ms = 1311
counter = 0; t_ms = 1308
counter = 0; t_ms = 1308
counter = 0; t_ms = 1309
counter = 0; t_ms = 1308
ter = 70173; t_ms = 1719
counter = 0; t_ms = 1307
counter = 0; t_ms = 1307
counter = 0; t_ms = 1308
counter = 0; t_ms = 1310
counter = 0; t_ms = 1303
counter = 0; t_ms = 1302
counter = 0; t_ms = 1309
counter = 0; t_ms = 1303
counter = 0; t_ms = 1304
counter = 0; t_ms = 1304
counter = 0; t_ms = 1303
counter = 0; t_ms = 1308
counter = 0; t_ms = 1306
counter = 0; t_ms = 1303
counter = 0; t_ms = 1308
counter = 0; t_ms = 1306
counter = 0; t_ms = 1308
counter = 0; t_ms = 1307

Using TrinketHidCompatibleDelay(2000) at the beginning of setup() pretty much guarantees a successful startup with good prints.

Here's some of its outputs:

counter = 0; t_ms = 2306
counter = 0; t_ms = 2306
counter = 0; t_ms = 2309
counter = 0; t_ms = 2311
counter = 0; t_ms = 2308
counter = 0; t_ms = 2309

Why? Is there a better way? Is this a bug somewhere in the USB HID code?

[comp500]

Thank you so much for this TrinketHidCompatibleDelay function. It completely fixed the connection issues I was having with TrinketKeyboard.