CFG_TUSB_DEBUG=2 Serial deadlock on nRF52840

Operating System

MacOS

Arduino IDE version

1.18.19

Board

Feather nRF52840 Express

ArduinoCore version

1.6.1

TinyUSB Library version

3.1.3

Sketch as ATTACHED TXT

examples/HID/hid_boot_keyboard

Compiled Log as ATTACHED TXT

hid_boot_keyboard.build.log.txt

What happened ?

Debug output halts partway through TinyUSB initialization. The host cannot enumerate the device. Attaching with GDB shows what appears an infinite loop inside FreeRTOS, due to a corrupted task list.

How to reproduce ?

Open the hid_boot_keyboard example sketch.
Select Debug level 2 and Debug port Serial1
Compile and upload the sketch
Monitor output from Serial1
Observe that debug output seems truncated, and host does not enumerate the device

Debug Log

USBD init on controller 0
sizeof(usbd_device_t) = 56
sizeof(dcd_event_t) = 12
sizeof(tu_fifo_t) = 20
sizeof(tu_edpt_stream_t) = 112
CDC init
MSC init
HID init
VIDEO init
MIDI init
VENDOR init
dcd init
Power USB event: Detected

Normal debug log, via SEGGER RTT, on this host continues with:

Power USB event: Detected
Power USB event: Ready
USBD Bus Reset : Full Speed

USBD Setup Received 80 06 00 01 00 00 08 00
  Get Descriptor Device
  Queue EP 80 with 8 bytes ...
USBD Xfer Complete on EP 80 with 8 bytes
  Queue EP 00 with 0 bytes ...
USBD Xfer Complete on EP 00 with 0 bytes
USBD Bus Reset : Full Speed

etc.

Note that SEGGER RTT output currently requires fixing an include statement on nRF52, plus adding -DUSE_SEGGER_RTT to defines.

Screenshots

Backtrace from GDB after deadlock:

#0  0x00031132 in vListInsert (pxList=pxList@entry=0x2000a1bc,
    pxNewListItem=0x200076f0 <vApplicationGetIdleTaskMemory::xIdleTaskTCB+24>)
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/cores/nRF5/freertos/Source/list.c:150
#1  0x0002f300 in vTaskPlaceOnEventList (
    pxEventList=pxEventList@entry=0x2000a1bc, xTicksToWait=4294967295)
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/cores/nRF5/freertos/Source/tasks.c:2935
#2  0x0002e474 in xQueueSemaphoreTake (xQueue=0x2000a198,
    xTicksToWait=<optimized out>, xTicksToWait@entry=4294967295)
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/cores/nRF5/freertos/Source/queue.c:1533
#3  0x00030986 in Uart::write (size=<optimized out>, buffer=<optimized out>,
    this=<optimized out>)
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/cores/nRF5/Uart.cpp:243
#4  Uart::write (this=0x2000762c <Serial1>,
    buffer=0x2003fe50 "Power USB event: Ready\r\n",
    buffer@entry=0x2003fe30 "<r", size=24)
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/cores/nRF5/Uart.cpp:232
#5  0x00026814 in Print::write (str=0x2003fe30 "<r", this=<optimized out>)
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/cores/nRF5/Print.h:53
--Type <RET> for more, q to quit, c to continue without paging--
#6  log_printf (format=0x35f40 "Power USB event: %s\r\n")
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/libraries/Adafruit_TinyUSB_Arduino/src/arduino/Adafruit_TinyUSB_API.cpp:89
#7  0x0002ce36 in tusb_hal_nrf_power_event (event=2)
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/libraries/Adafruit_TinyUSB_Arduino/src/portable/nordic/nrf5x/dcd_nrf5x.c:985
#8  <signal handler called>
#9  0x0002fdc2 in vPortStartFirstTask ()
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/cores/nRF5/freertos/portable/GCC/nrf52/port.c:53
#10 0x0002fad2 in xPortStartScheduler ()
    at /Users/tlyu/Library/Arduino15/packages/adafruit/hardware/nrf52/1.6.1/cores/nRF5/freertos/portable/CMSIS/nrf52/port_cmsis.c:240
#11 0x200076d8 in _loopHandle ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

adafruit / Adafruit_TinyUSB_Arduino