tools-only Embedded Debug Tools
Commands for flashing, debugging, and inspecting nRF52 and STM32 targets.
Tool Overview
| Tool | Vendor | Targets | Primary Use |
|---|---|---|---|
| nrfjprog | Nordic | nRF51/52/53/91 | Flash, erase, reset |
| OpenOCD | Open Source | ARM Cortex-M | GDB server, flash |
| STM32_Programmer_CLI | ST | STM32 | Flash, OTP, option bytes |
| J-Link Commander | SEGGER | All ARM | Flash, RTT, SWO |
nrfjprog (Nordic)
Installation
# Download from Nordic website or use nRF Command Line Tools
# https://www.nordicsemi.com/Products/Development-tools/nRF-Command-Line-Tools
# Linux: Add to PATH after install
export PATH="$PATH:/opt/nrf-command-line-tools/bin"
Common Commands
# List connected devices
nrfjprog --ids
# Erase all flash
nrfjprog --eraseall
# Program hex file
nrfjprog --program firmware.hex --verify
# Program with specific device (if multiple connected)
nrfjprog --snr 683123456 --program firmware.hex
# Reset target
nrfjprog --reset
# Soft reset (preserve RAM)
nrfjprog --pinreset
# Read device info
nrfjprog --deviceversion
nrfjprog --memrd 0x10000000 --n 16 # Read FICR
# Read memory range
nrfjprog --memrd <address> --n <bytes>
# Write memory
nrfjprog --memwr <address> --val <value>
# Recover locked device (full erase)
nrfjprog --recover
Programming Workflow
# Full programming sequence
nrfjprog --eraseall && \
nrfjprog --program softdevice.hex --verify && \
nrfjprog --program application.hex --verify && \
nrfjprog --reset
Debug with GDB
# Start GDB server (in terminal 1)
JLinkGDBServer -device nRF52840_xxAA -if SWD -speed 4000
# Connect GDB (in terminal 2)
arm-none-eabi-gdb build/zephyr/zephyr.elf
(gdb) target remote localhost:2331
(gdb) monitor reset
(gdb) load
(gdb) break main
(gdb) continue
OpenOCD
Installation
# Ubuntu/Debian
sudo apt install openocd
# macOS
brew install openocd
# From source (for latest)
git clone https://github.com/openocd-org/openocd.git
cd openocd && ./bootstrap && ./configure && make && sudo make install
Configuration Files
# Location of config files
ls /usr/share/openocd/scripts/
# Common interface configs
interface/stlink.cfg # ST-Link
interface/jlink.cfg # J-Link
interface/cmsis-dap.cfg # CMSIS-DAP
# Common target configs
target/stm32f4x.cfg
target/stm32l4x.cfg
target/nrf52.cfg
Starting OpenOCD
# STM32F4 with ST-Link
openocd -f interface/stlink.cfg -f target/stm32f4x.cfg
# nRF52 with J-Link
openocd -f interface/jlink.cfg -c "transport select swd" -f target/nrf52.cfg
# Custom config file
openocd -f board/my_board.cfg
OpenOCD Commands (via telnet or GDB)
# Connect via telnet
telnet localhost 4444
# Commands
> reset halt # Reset and halt CPU
> flash write_image erase firmware.bin 0x08000000 # Flash binary
> flash write_image erase firmware.hex # Flash hex (auto address)
> verify_image firmware.bin 0x08000000 # Verify flash
> reset run # Reset and run
> halt # Halt execution
> resume # Resume execution
> reg # Show registers
> mdw 0x20000000 16 # Read 16 words from address
> mww 0x20000000 0x12345678 # Write word to address
GDB with OpenOCD
# Start OpenOCD (terminal 1)
openocd -f interface/stlink.cfg -f target/stm32f4x.cfg
# Connect GDB (terminal 2)
arm-none-eabi-gdb build/firmware.elf
(gdb) target extended-remote localhost:3333
(gdb) monitor reset halt
(gdb) load
(gdb) break main
(gdb) continue
OpenOCD Config Example
# board/custom_stm32f4.cfg
source [find interface/stlink.cfg]
transport select hla_swd
source [find target/stm32f4x.cfg]
# Set flash size (for auto-detect issues)
set FLASH_SIZE 0x100000
# Increase adapter speed
adapter speed 4000
# Reset configuration
reset_config srst_only srst_nogate
STM32_Programmer_CLI
Installation
Part of STM32CubeProgrammer - download from ST website.
# Add to PATH (Linux)
export PATH="$PATH:/opt/stm32cubeprogrammer/bin"
# Verify installation
STM32_Programmer_CLI --version
Common Commands
# List connected devices
STM32_Programmer_CLI --connect port=SWD --list
# Connect and get device info
STM32_Programmer_CLI --connect port=SWD
# Erase full chip
STM32_Programmer_CLI --connect port=SWD --erasechip
# Program hex file
STM32_Programmer_CLI --connect port=SWD --write firmware.hex --verify
# Program binary at specific address
STM32_Programmer_CLI --connect port=SWD --write firmware.bin 0x08000000 --verify
# Read memory to file
STM32_Programmer_CLI --connect port=SWD --read 0x08000000 0x10000 read.bin
# Reset target
STM32_Programmer_CLI --connect port=SWD --hardRst
# Option bytes
STM32_Programmer_CLI --connect port=SWD --optionbytes display # Display
STM32_Programmer_CLI --connect port=SWD -ob RDP=0xAA # Set option byte
Programming with Reset Modes
# Hardware reset after programming
STM32_Programmer_CLI --connect port=SWD --mode UR --write firmware.hex --hardRst
# Connect under reset (for locked devices)
STM32_Programmer_CLI --connect port=SWD --mode UR --reset HWrst
External Loader (for QSPI/external flash)
# Program external flash
STM32_Programmer_CLI --connect port=SWD \
--extload "path/to/loader.stldr" \
--write firmware.bin 0x90000000 --verify
J-Link Commander
Installation
Download from SEGGER website.
# Start J-Link Commander
JLinkExe
# Or with device specified
JLinkExe -device nRF52840_xxAA -if SWD -speed 4000 -autoconnect 1
Common Commands
J-Link> connect # Interactive connect
J-Link> device nRF52840_xxAA # Set device
J-Link> si SWD # Select interface
J-Link> speed 4000 # Set speed in kHz
J-Link> r # Reset and halt
J-Link> g # Go (run)
J-Link> h # Halt
J-Link> loadfile firmware.hex # Load hex file
J-Link> loadbin firmware.bin 0x0 # Load binary at address
J-Link> erase # Erase flash
J-Link> mem32 0x20000000 16 # Read 16 words
J-Link> w4 0x20000000 0x1234 # Write word
J-Link> rtt start # Start RTT
J-Link> rtt read 0 # Read from RTT channel 0
Batch Mode
# Create command file (commands.jlink)
r
loadfile firmware.hex
r
g
exit
# Run batch
JLinkExe -device nRF52840_xxAA -if SWD -speed 4000 -CommandFile commands.jlink
RTT (Real-Time Transfer)
# Start RTT client
JLinkRTTClient
# Or with RTT Viewer GUI
JLinkRTTViewerExe
West (Zephyr Build Tool)
Build and Flash
# Build for board
west build -b nrf52840dk_nrf52840 app/
# Flash
west flash
# Flash with specific runner
west flash --runner jlink
west flash --runner nrfjprog
west flash --runner openocd
# Debug
west debug
# Attach to running target
west attach
Useful West Commands
# List supported boards
west boards | grep nrf
# Build with pristine (clean)
west build -b nrf52840dk_nrf52840 -p auto app/
# Build specific configuration
west build -b nrf52840dk_nrf52840 -- -DCONF_FILE=prj_debug.conf
# Generate compile_commands.json
west build -b nrf52840dk_nrf52840 -- -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
Troubleshooting
Target Not Found
# Check USB permissions (Linux)
sudo usermod -a -G dialout $USER
# Create udev rules for debug probes
# Check probe connection
lsusb | grep -i "segger\|stlink\|nordic"
# Reset probe
# ST-Link: unplug/replug
# J-Link: JLinkExe -> usbreset
Flash Verification Failed
# Ensure target is halted
# Check for flash write protection
# Verify correct start address for binary files
# Try mass erase before programming
Connection Under Reset
# For locked or crashed devices
# nrfjprog:
nrfjprog --recover
# OpenOCD:
openocd -f interface/stlink.cfg -f target/stm32f4x.cfg \
-c "init; reset halt; flash write_image erase firmware.hex; reset run; exit"
# STM32_Programmer_CLI:
STM32_Programmer_CLI --connect port=SWD mode=UR reset=HWrst