linguini1 opened a new issue, #16444:
URL: https://github.com/apache/nuttx/issues/16444
### Description / Steps to reproduce the issue
The USART0 serial console does not work on ATMega2560 chips.
To reproduce:
```console
$ ./tools/configure.sh arduino-mega2560:nsh
$ make -j
```
flash the image to the Arduino Mega2560 board.
Connect a USB-to-serial cable to pins 0 & 1 (RX0 & TX0) and GND. Observe no
serial output at a baud rate of 38400, nor response to any input. Reboot the
board with the serial monitor still connected and see the same thing again.
If you add `avr_lowputc` calls in the board initialization code, you'll see
that the `TX` LED stays stuck on indefinitely.
### On which OS does this issue occur?
[OS: Linux]
### What is the version of your OS?
Linux 6.14.6-arch1-1 SMP PREEMPT_DYNAMIC x86_64 GNU/Linux
### NuttX Version
master
### Issue Architecture
[Arch: avr]
### Issue Area
[Area: Specific Peripheral]
### Host information
NuttX CFLAGS:
-fno-common
-Wall
-Wstrict-prototypes
-Wshadow
-Wundef
-Wno-attributes
-Wno-unknown-pragmas
-O2
-fno-strict-aliasing
-fomit-frame-pointer
-mmcu=atmega2560
-isystem /home/linguini/coding/nuttx-space/nuttx/include
-D__NuttX__
-DNDEBUG
NuttX CXXFLAGS:
-fno-common
-Wall
-Wshadow
-Wundef
-Wno-attributes
-Wno-unknown-pragmas
-nostdinc++
-fno-exceptions
-fcheck-new
-fno-rtti
-O2
-fno-strict-aliasing
-fomit-frame-pointer
-mmcu=atmega2560
-isystem /home/linguini/coding/nuttx-space/nuttx/include/cxx
-isystem /home/linguini/coding/nuttx-space/nuttx/include
-D__NuttX__
-DNDEBUG
NuttX LDFLAGS:
-mavr6
-Map=/home/linguini/coding/nuttx-space/nuttx/nuttx.map
-nostdlib
NuttX configuration options:
CONFIG_DEFAULT_SMALL=y
CONFIG_HOST_LINUX=y
CONFIG_APPS_DIR=\../apps\
CONFIG_BASE_DEFCONFIG=\arduino-mega2560:hello\
CONFIG_BUILD_FLAT=y
CONFIG_INTELHEX_BINARY=y
CONFIG_OUTPUT_STRIP_PATHS=y
CONFIG_ARCH_NONE_DEBUG_H=y
CONFIG_FORTIFY_SOURCE=0
CONFIG_NDEBUG=y
CONFIG_DEBUG_ALERT=y
CONFIG_ARCH_HAVE_STACKCHECK=y
CONFIG_STACK_USAGE_WARNING=0
CONFIG_DEBUG_SYMBOLS=y
CONFIG_DEBUG_SYMBOLS_LEVEL=\-g\
CONFIG_ARCH_HAVE_CUSTOMOPT=y
CONFIG_DEBUG_FULLOPT=y
CONFIG_LTO_NONE=y
CONFIG_DEBUG_LINK_MAP=y
CONFIG_ARCH_AVR=y
CONFIG_ARCH=\avr\
CONFIG_ARCH_FAMILY=\avr\
CONFIG_ARCH_CHIP=\atmega\
CONFIG_ARCH_CHIP_ATMEGA=y
CONFIG_ARCH_FAMILY_AVR=y
CONFIG_AVR_LINUXGCC_TOOLCHAIN=y
CONFIG_AVR_HAS_RAMPZ=y
CONFIG_ARCH_CHIP_ATMEGA2560=y
CONFIG_AVR_USART0=y
CONFIG_ARCH_TOOLCHAIN_GNU=y
CONFIG_ARCH_TOOLCHAIN_GCC=y
CONFIG_ARCH_NOINTC=y
CONFIG_ARCH_STACKDUMP=y
CONFIG_ARCH_STACKDUMP_MAX_LENGTH=0
CONFIG_BOARD_LOOPSPERMSEC=800
CONFIG_ARCH_HAVE_INTERRUPTSTACK=y
CONFIG_ARCH_INTERRUPTSTACK=0
CONFIG_BOOT_RUNFROMFLASH=y
CONFIG_RAM_START=0x800100
CONFIG_RAM_SIZE=8192
CONFIG_FLASH_START=0x0
CONFIG_FLASH_SIZE=0
CONFIG_ARCH_BOARD_ARDUINO_MEGA2560=y
CONFIG_ARCH_BOARD=\arduino-mega2560\
CONFIG_BOARD_CRASHDUMP_NONE=y
CONFIG_BOARD_MEMORY_RANGE=\\
CONFIG_DISABLE_OS_API=y
CONFIG_DISABLE_POSIX_TIMERS=y
CONFIG_DISABLE_PTHREAD=y
CONFIG_DISABLE_MQUEUE=y
CONFIG_DISABLE_MQUEUE_SYSV=y
CONFIG_DISABLE_ENVIRON=y
CONFIG_USEC_PER_TICK=10000
CONFIG_TIMER_ADJUST_USEC=0
CONFIG_START_YEAR=2011
CONFIG_START_MONTH=6
CONFIG_START_DAY=16
CONFIG_IRQ_NWORKS=8
CONFIG_IRQ_WORK_SECTION=\\
CONFIG_IRQ_WORK_STACKSIZE=2048
CONFIG_INIT_ENTRY=y
CONFIG_INIT_ARGS=\\
CONFIG_INIT_STACKSIZE=128
CONFIG_INIT_PRIORITY=100
CONFIG_INIT_ENTRYPOINT=\hello_main\
CONFIG_INIT_ENTRYNAME=\hello_main\
CONFIG_RR_INTERVAL=0
CONFIG_TASK_NAME_SIZE=0
CONFIG_SCHED_CPULOAD_NONE=y
CONFIG_SCHED_CPULOAD_TICKSPERSEC=100
CONFIG_SCHED_PROFILE_TICKSPERSEC=1000
CONFIG_SCHED_STACK_RECORD=0
CONFIG_DEV_CONSOLE=y
CONFIG_NFILE_DESCRIPTORS_PER_BLOCK=4
CONFIG_SIG_PREALLOC_ACTIONS=4
CONFIG_SIG_ALLOC_ACTIONS=1
CONFIG_SIG_PREALLOC_IRQ_ACTIONS=4
CONFIG_DEFAULT_TASK_STACKSIZE=2048
CONFIG_IDLETHREAD_STACKSIZE=128
CONFIG_PTHREAD_STACK_MIN=128
CONFIG_PTHREAD_STACK_DEFAULT=128
CONFIG_PID_INITIAL_COUNT=8
CONFIG_DEV_OPTEE_NONE=y
CONFIG_ARCH_HAVE_SERIAL_TERMIOS=y
CONFIG_SERIAL=y
CONFIG_SERIAL_CONSOLE=y
CONFIG_MCU_SERIAL=y
CONFIG_STANDARD_SERIAL=y
CONFIG_SERIAL_NPOLLWAITERS=4
CONFIG_USART0_SERIAL_CONSOLE=y
CONFIG_USART0_SERIALDRIVER=y
CONFIG_USART0_RXBUFSIZE=256
CONFIG_USART0_TXBUFSIZE=256
CONFIG_USART0_BAUD=38400
CONFIG_USART0_BITS=8
CONFIG_USART0_PARITY=0
CONFIG_USART0_2STOP=0
CONFIG_SYSLOG=y
CONFIG_SYSLOG_DEFAULT_MASK=0xff
CONFIG_SYSLOG_CRLF=y
CONFIG_SYSLOG_MAX_CHANNELS=1
CONFIG_SYSLOG_DEVPATH=\/dev/ttyS1\
CONFIG_SYSLOG_DEFAULT=y
CONFIG_CONSOLE_SYSLOG=y
CONFIG_DISABLE_MOUNTPOINT=y
CONFIG_FS_NEPOLL_DESCRIPTORS=8
CONFIG_FS_LOCK_BUCKET_SIZE=0
CONFIG_DISABLE_PSEUDOFS_OPERATIONS=y
CONFIG_SENDFILE_BUFSIZE=512
CONFIG_FS_BACKTRACE=0
CONFIG_NXFONTS_PACKEDMSFIRST=y
CONFIG_MM_DEFAULT_MANAGER=y
CONFIG_MM_DEFAULT_ALIGNMENT=8
CONFIG_MM_SMALL=y
CONFIG_MM_REGIONS=1
CONFIG_MM_MAP_COUNT_MAX=1024
CONFIG_MM_BACKTRACE=-1
CONFIG_MM_FREE_DELAYCOUNT_MAX=0
CONFIG_MM_HEAP_BIGGEST_COUNT=30
CONFIG_MM_HEAP_MEMPOOL_THRESHOLD=-1
CONFIG_BINFMT_DISABLE=y
CONFIG_BINFMT_ELF_RELOCATABLE=y
CONFIG_STDIO_BUFFER_SIZE=0
CONFIG_STDIO_LINEBUFFER=y
CONFIG_NUNGET_CHARS=0
CONFIG_ARCH_LOWPUTC=y
CONFIG_LIBC_RAND_ORDER=1
CONFIG_LIBC_HOMEDIR=\/\
CONFIG_LIBC_TMPDIR=\/tmp\
CONFIG_LIBC_MAX_TMPFILE=32
CONFIG_LIBC_MAX_EXITFUNS=0
CONFIG_POSIX_SPAWN_DEFAULT_STACKSIZE=2048
CONFIG_LIBC_HOSTNAME=\\
CONFIG_LIBC_OPEN_MAX=256
CONFIG_NAME_MAX=32
CONFIG_PATH_MAX=256
CONFIG_LINE_MAX=64
CONFIG_LIBC_STRSIGNAL=y
CONFIG_LIBC_STRSIGNAL_SHORT=y
CONFIG_TLS_TASK_NELEM=0
CONFIG_TLS_NCLEANUP=0
CONFIG_LIBC_GAISTRERROR_ERRNUM=y
CONFIG_LIBC_FTOK_VFS_PATH=\/var/ftok\
CONFIG_LIBC_MEMFD_ERROR=y
CONFIG_LIBC_MUTEX_BACKTRACE=0
CONFIG_STREAM_OUT_BUFFER_SIZE=64
CONFIG_STREAM_HEXDUMP_BUFFER_SIZE=128
CONFIG_STREAM_BASE64_BUFFER_SIZE=128
CONFIG_LIBM_NONE=y
CONFIG_BUILTIN_TOOLCHAIN=y
CONFIG_COVERAGE_NONE=y
CONFIG_COVERAGE_DEFAULT_PREFIX_STRIP=\99\
CONFIG_COVERAGE_DEFAULT_PREFIX=\/data\
CONFIG_PROFILE_NONE=y
CONFIG_EXAMPLES_HELLO=y
CONFIG_EXAMPLES_HELLO_PROGNAME=\hello\
CONFIG_EXAMPLES_HELLO_PRIORITY=100
CONFIG_EXAMPLES_HELLO_STACKSIZE=2048
Host system OS:
Linux pastabox 6.14.6-arch1-1 #1 SMP PREEMPT_DYNAMIC Fri 09 May 2025
17:36:18 +0000 x86_64
Host system PATH:
/home/linguini/.cargo/bin
/sbin
/bin
/usr/local/sbin
/usr/local/bin
/usr/sbin
/usr/bin
/opt/cuda/bin
/opt/cuda/nsight_compute
/opt/cuda/nsight_systems/bin
/usr/lib/jvm/default/bin
/usr/bin/site_perl
/usr/bin/vendor_perl
/usr/bin/core_perl
/opt/rocm/bin
/usr/lib/rustup/bin
### Verification
- [x] I have verified before submitting the report.
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