[gen4] hal: get rid of unnecessary constant delay(1) in HAL_USB_USART_Send_Data()

[avtolstoy]

Problem

We are always unnecessarily delaying 1ms on each byte sent over USB serial.

Moreover this happens even if there is no host connected, as _blocking = true by default and Serial::write() is implemented as following and always goes down to HAL_USB_USART_Send_Data():

size_t USBSerial::write(uint8_t byte)
{
  if (HAL_USB_USART_Available_Data_For_Write(_serial) > 0 || _blocking) {
    return std::max(0, (int)HAL_USB_USART_Send_Data(_serial, byte));
  }
  return 0;
}

Solution

Get rid of it. In addition to that fixes the FIXME about thread priorities. Don't need to delay(1) if we are below USB ISR processing task.

Steps to Test

N/A

Example App

N/A

References

• [SC133780]

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Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[scott-brust]

Just some questions