CFG_TUSB_DEBUG=2 Serial deadlock on nRF52840

[tlyu]

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?)