N00b: 7 blinks while building simple project with debug print

[JimmyJams]

Hi everybody,

I'm new to the Teensy board, and I'm trying to learn more about it by tinkering with some Adafruit peripherals.
I was trying to build this in PlatformIO (moving functions to make it compile in C++): https://github.com/adafruit/Adafruit_SSD1327/blob/master/examples/ssd1327_test/ssd1327_test.ino
Without adding TeensyDebug it builds and works nicely, but just adding debug.begin(SerialUSB1); in the setup() function makes the board blink its led 7 times when uploading the binary.
The problem seems to be related if the constructor of Adafruit_SSD1327 is called, either globally or scoped in a function.
The same happens without adding TeensyDebug when I uncomment the define for PRINT_DEBUG_STUFF in packages/framework-arduinoteensy/cores/teensy4/debug/printf.h.

I'm using the latest Visual Studio Code with the latest PlatformIO.

The simplest way I've found to reproduce it on my board is to use the code below.
With the PRINT_DEBUG_STUFF macro not defined, it builds and run. I get seven blinks with the macro enabled.

Any idea what I may be doing wrong?

Code:

#include <Arduino.h>
#include <TeensyDebug.h>

void setup() {
  Serial.begin(115200);
  debug.begin(SerialUSB1);
}

void loop() {
  Serial.println("Alive and kicking");
  delay(100);
}

platformio.ini

; PlatformIO Project Configuration File
;
;   Build options: build flags, source filter
;   Upload options: custom upload port, speed and extra flags
;   Library options: dependencies, extra library storages
;   Advanced options: extra scripting
;
; Please visit documentation for the other options and examples
; https://docs.platformio.org/page/projectconf.html

[env:teensy41]
platform = teensy
board = teensy41
framework = arduino
upload_protocol = teensy-cli
lib_deps =
    https://github.com/ftrias/TeensyDebug

build_type = debug
build_unflags = -DUSB_SERIAL
build_flags = -DUSB_DUAL_SERIAL
debug_port = /dev/cu.usbmodem145015603 
debug_tool = custom
debug_load_mode = manual
debug_server = 
debug_init_cmds =
  target extended-remote $DEBUG_PORT
  $INIT_BREAK
  define pio_reset_run_target
  interrupt
  tbreak loop
  continue
  end
  define pio_restart_target
  echo Restart is undefined for now.
  end

debug_init_break =

 

[defragster]

meaning of blink codes here : pjrc.com/store/ic_mkl02_t4.html

for 7 it shows:

7 Blinks = ARM JTAG DAP Communication Error
A communication error was detected, but after correctly detecting (4 blinks) and initializing the ARM JTAG DAP (9 blinks). 
Programs which crash or have unusual startup behavior can cause a temporary 7 blink error at startup. With a known-good 
program or blank flash chip, this error may indicate a severe signal quality problem or any of the signal wires shorted to 
other lines which are initially high impedance but become output after a program is running. But these types of hardware
issues are unusual, because hardware trouble for 7 blinks requires first successfully passing tests which would cause
4 or 9 blinks. 7 blinks can also be shown if the processor reboots, either by software write to SCB_AIRCR or due to fault 
or other error handling, while communication is in progress. If you see 7 blinks, program the flash memory with a simple 
known-good code before investigating hardware trouble.

That suggests it could be troubled code.

Not sure what is in TeensyDebug - (use a working simple example and get the debug working) and how the build on PIO is affecting this.

If built with TeensyDuino current ver. 1.59 Beta 3 in the IDE the result might be different. Some changes were made to affect cpp constructors IIRC.