--- title: Flashing via RIOT's Build System description: Guide on how to flash boards using RIOT's build system --- ## General Approach In general, flashing a board from RIOT is as straight forward as typing in a shell (with the application directory as current working directory): ```sh make BOARD= flash ``` This will **rebuild** ***AND*** **flash** the application in the current working directory for board ``, using its default programming tool. If you want to use an alternative programming tool, say `stm32flash`, use: ```sh make BOARD= PROGRAMMER=stm32flash flash ``` To flash without rebuilding use `flash-only` as target instead of `flash`. ## Supported Tools RIOT supports plenty of flashing tools, that are below grouped into general flashing tools that support multiple MCU families, and specialized tools that only support one platform. Note that some programmers require additional configuration on a per board level or rely on features only available on some boards. Hence, a given board may not be supported by a programmer listed as supported for the platform of the board due to a missing board feature, bootloader, or similar. To ease use the programmers are given by the value to pass via `PROGRAMMER=`, rather than the official spelling of the programmer. ### Compatibility Matrix of Generic Tools MCU Family | `bmp` | `dfu-util` | `jlink` | `openocd` | `pyocd` | `uf2conv` ---------------|--------|------------|---------|-----------|---------|---------- ATmega | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ ATXmega | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ CC13xx / C26xx | ✗ | ✗ | ✓ | ✓ (1) | ✗ | ✗ CC2538 | ✗ | ✗ | ✓ | ✗ | ✗ | ✗ EFM32 | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ ESP8266 | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ ESP32 (Xtensa) | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ ESP32 (RISC-V) | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ FE310 | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ GD32V | ✗ | ✗ | ✗ | ✓ (1) | ✗ | ✗ Kinetis | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ LPC1768 | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ LPC23xx | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ MIPS32r2 | ✗ | ✗ | ✓ | ✗ | ✗ | ✗ MSP430 | ✗ | ✗ | ✗ | ✗ | ✗ | ✗ nRF51 | ✗ | ✗ | ✓ | ✓ | ✓ | ✗ nRF52 | ✓ | ✗ | ✓ | ✓ | ✓ | ✓ RP2040 | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ SAM | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ Stellaris | ✗ | ✗ | ✓ | ✓ | ✗ | ✗ STM32 | ✓ | ✓ | ✓ | ✓ | ✗ | ✗ Remarks: 1. Requires a patched version of the programmer tool ### Specialized Flashing Tools Per Platform The following list only contains single-platform flashing tools. Tools that support multiple platforms are given in section above. #### AVR - `avrdude` #### CC13xx / CC26xx - `uniflash` #### CC2538 - `cc2538-bsl` #### ESP8266 / ESP32 (Xtensa) / ESP32 (RISC-V) - `esptool` #### LPC23xx - `lpc2k_pgm` #### MSP430 - `mspdebug` - `goodfet` #### nRF52 - `adafruit-nrfutil`, `uf2conv` (requires Adafruit bootloader), see [Adafruit nRF52 Bootloader Common](https://doc.riot-os.org/group__boards__common__adafruit-nrf52-bootloader.html) - `nrfutil` (required nRF bootloader) - `nrfjprog` (requires a separate J-Link debugger) #### RP2040 / RP2350 - `picotool` #### SAM - `bossa` - `edbg` #### STM32 - `stm32flash` - `stm32loader` - `cpy2remed` (requires integrated ST-Link programmer, e.g. Nucleo boards) - `robotis-loader` (requires robotis bootloader, only one board supported) See also: [STM32 Flashing Guide](/board_specific/stm32) ## Programmer Configuration This section will list additional configuration options to control the behavior of a programming tool, such as selecting the hardware adapter used for programming. ### OpenOCD Configuration #### OPENOCD_DEBUG_ADAPTER `OPENOCD_DEBUG_ADAPTER` can be set via command line or as environment variable to use non-default flashing hardware. #### OPENOCD_RESET_USE_CONNECT_ASSERT_SRST `OPENOCD_RESET_USE_CONNECT_ASSERT_SRST` can be set via command line or as environment variable to `0` to disable resetting the board via the `SRST` line. This is useful when the `SRST` signal is not connected to the debug adapter or when using cheap ST-Link V2 clones with broken `SRST` output. Note that it may not be possible to attach the debugger while the MCU is in deep sleeping mode. If this is set to `0` by the user, the user may need a carefully timed reset button press to be able to flash the board. #### OPENOCD_PRE_FLASH_CMDS `OPENOCD_PRE_FLASH_CMDS` can be set as environment variable to pass additional commands to OpenOCD prior to flashing, e.g. to disable flash write protection. #### OPENOCD_PRE_VERIFY_CMDS `OPENOCD_PRE_VERIFY_CMDS` can be set as environment variable to pass additional flags to OpenOCD prior to verifying the flashed firmware. E.g. this is used in the `pba-d-01-kw2x` to disable the watchdog to prevent it from disrupting the verification process. #### OPENOCD_PRE_FLASH_CHECK_SCRIPT `OPENOCD_PRE_FLASH_CHECK_SCRIPT` can be set via command line or as environment variable to execute a script before OpenOCD starts flashing. It is used for Kinetis boards to prevent bricking a board by locking the flash via magic value in the flash configuration field protection bits. The script is expected to exit with code `0` if flashing should resume, or with exit code `1` if flashing should be aborted. #### OPENOCD_CONFIG `OPENOCD_DEBUG_ADAPTER` can be set via command line or as environment variable to use non-default OpenOCD configuration file. #### OPENOCD_TRANSPORT `OPENOCD_TRANSPORT` can be set via command line or as environment variable to select a non-default transport protocol. E.g. to use JTAG rather than SWD for a board that defaults to SWD use: ```sh make PROGRAMMER=openocd OPENOCD_TRANSPORT=jtag ``` Note that the OpenOCD configuration file of a given board may only support SWD or JTAG. Also JTAG requires more signal lines to be connected compared to SWD and some internal programmers only have the SWD signal lines connected, so that JTAG will not be possible. ### MSPDEBUG Configuration All options can be passed as environment variables or as make arguments. All options except for `DEBUGSERVER_PORT` apply to both debugging and flashing alike. `MSPDEBUG_PROGRAMMER` is used to set the hardware programmer/debugger to use for programming and debugging. See `mspdebug --help` or `man mspdebug` for a list of programmers. `MSPDEBUG_PROTOCOL` is used to specify the debugger protocol. It is typically set by the board used. Only JTAG and Spi-Bi-Wire are supported. `MSPDEBUG_TTY` is used to connect via TTY interface instead of directly via USB to the debugger. Usually, this is not required. `DEBUG_ADAPTER_ID` is used to select the debugger/programmer by its serial. If not set, `mspdebug` will select the first device with matching vendor and product ID. Unless multiple debuggers of the same type are connected, this options is typically not needed. `DEBUGSERVER_PORT` is used to specify the TCP port to listen for GDB to connect to. It defaults to 2000. ### Handling Multiple Boards with UDEV-Rules When developing and working with multiple boards the default `PORT` configuration for a particular board might not apply anymore, so `PORT` will need to be specified whenever calling `make term/test`. This can also happen if multiple `DEBUGGERS/PROGRAMMERS` are present so `DEBUG_ADAPTER_ID` will also need to be passed. Keeping track of this will become annoying. One way of handling this is to use `udev` rules to define `SYMLINKS` between the boards serial port (`riot/tty-`) and the actual serial port (dev/ttyACM* or other). With this we can query the rest of the boards serial `dev` information (`DEBUG_ADAPTER_ID`, `PORT`, etc.) to always flash and open a terminal on the correct port. #### Procedure - use `udevadm info /dev/ttyACM0` to query the udev database for information on device on port `/dev/ttyACM0`. - or: use `udevadm info --attribute-walk --name /dev/ttyACM0` for more detailed output when the first level of information isn't enough - create a udev rule with information of the device and one parent to create a matching rule in `/etc/udev/rules.d/70-riotboards.rules`. ``` # samr21-xpro SUBSYSTEM=="tty", SUBSYSTEMS=="usb", ATTRS{idVendor}=="03eb", \ ATTRS{idProduct}=="2111", ATTRS{manufacturer}=="Atmel Corp.", \ ATTRS{serial}=="ATML2127031800004957", SYMLINK+="riot/tty-samr21-xpro" ``` - reload rules: `udevadm control --reload-rules` - Boards `PORT` are symlinked to /dev/riot/tty-`board-name`. - Create a `makefile.pre` that will query the real `PORT` and the `DEBUG_ADAPTER_ID` from the `SYMLINK` info ```makefile PORT = /dev/riot/tty-$(BOARD) DEBUG_ADAPTER_ID = $(\ shell udevadm info -q property $(PORT) |\ sed -n '/ID_SERIAL_SHORT/ {s/ID_SERIAL_SHORT=//p}') ``` - You can now add `makefile.pre` to `RIOT_MAKEFILES_GLOBAL_PRE` as an environment variable or on each `make` call: ```sh $ RIOT_MAKEFILES_GLOBAL_PRE=/path/to/makefile.pre make -C examples/basic/hello-world flash term ``` :::note If set as an environment variable it would be a good idea to add a variable to enable/disable it, e.g: ```makefile ifeq (1,$(ENABLE_LOCAL_BOARDS)) PORT = /dev/riot/tty-$(BOARD) DEBUG_ADAPTER_ID = $(\ shell udevadm info -q property $(PORT) |\ sed -n '/ID_SERIAL_SHORT/ {s/ID_SERIAL_SHORT=//p}') endif ``` ::: ### Handling Multiple Versions of the same BOARD The above procedure works fine when handling different boards, but not multiple times the same board, e.g: multiple `samr21-xpro`. An option for this would be to add an identifier of that board to the mapped `riot/tty-*`, there are multiple ways of handling this but in the end it means having a way to identify every copy. Another way would be to map the `DEBUG_ADAPTER_ID` in the name: ```makefile SYMLINK+="riot/node-$attr{serial} ``` But it will require to know in advance the serial number of each board you want to use. Another option would be to add some kind of numbering and defining multiple symlinks for each board. e.g. for `samr21-xpro` number `n`: ``` # samr21-xpro SUBSYSTEM=="tty", SUBSYSTEMS=="usb", ATTRS{idVendor}=="03eb", \ ATTRS{idProduct}=="2111", ATTRS{manufacturer}=="Atmel Corp.", \ ATTRS{serial}=="ATML2127031800004957", SYMLINK+="riot/tty-samr21-xpro", \ SYMLINK+="riot/tty-samr21-xpro-n" ``` Then, when flashing, the number can be specified and the parsing adapted: ```makefile ifneq (,$(BOARD_NUM)) PORT = /dev/riot/tty-$(BOARD)-$(BOARD_NUM) else PORT = /dev/riot/tty-$(BOARD) endif DEBUG_ADAPTER_ID = $(\ shell udevadm info -q property $(PORT) |\ sed -n '/ID_SERIAL_SHORT/ {s/ID_SERIAL_SHORT=//p}') ``` ```sh BOARD=samr21-xpro BOARD_NUM=n make flash term ``` In the end, this would be the same as using the serial, but a simple number might be easier to handle. ### Notes Udev only parses SUBSYSTEM and one parent. For others, we will rely on ENV variables defined by 60-serial.rules So the current filename should be higher than 60-serial.rules If for some reason re-writing the serial is needed there is a windows tool: https://remoteqth.com/wiki/index.php?page=How+to+set+usb+device+SerialNumber ### Documentation * The whole documentation http://reactivated.net/writing_udev_rules.html#udevinfo * Udev manpage http://manpages.ubuntu.com/manpages/eoan/en/man7/udev.7.html ## Handling Multiple Boards without UDEV-Rules This is a simpler approach than the above mentioned issue. The solution here only uses a Makefile for selecting the debugger and serial port. No administrative privileges (e.g. to configure Udev) are required. One of the limitations of the solution described here is that it currently doesn't work with multiple boards of the same type. This is a limitation of the script and not of the mechanism used, it is possible to adapt the script to support multiple boards of the same type. This modification is left as an exercise to the reader. The following Make snippet is used: ```makefile LOCAL_BOARD_MAP ?= 1 # Adapt this list to your board collection SERIAL_nucleo-f103rb ?= 066BFF343633464257254156 SERIAL_same54-xpro ?= ATML2748051800005053 SERIAL_samr21-xpro ?= ATML2127031800008360 SERIAL_nrf52dk ?= 000682223007 ifeq (1,$(LOCAL_BOARD_MAP)) # Retrieve the serial of the selected board BOARD_SERIAL = $(SERIAL_$(BOARD)) # Check if there is a serial for the board ifneq (,$(BOARD_SERIAL)) # Set the variables used by various debug tools to the selected serial SERIAL ?= $(BOARD_SERIAL) DEBUG_ADAPTER_ID ?= $(BOARD_SERIAL) JLINK_SERIAL ?= $(BOARD_SERIAL) # Use the existing script to grab the matching /dev/ttyACM* device PORT ?= $(shell $(RIOTTOOLS)/usb-serial/ttys.py --most-recent --format path --serial $(SERIAL)) endif endif ``` The array of board serial numbers has to be edited to match your local boards. The serial numbers used here is the USB device serial number as reported by the debugger hardware. With the `make list-ttys` it is reported as the 'serial': ```sh $ make list-ttys path | driver | vendor | model | model_db | serial | ctime -------------|---------|--------------------------|--------------------------------------|-----------------------|--------------------------|--------- /dev/ttyUSB0 | cp210x | Silicon Labs | CP2102 USB to UART Bridge Controller | CP210x UART Bridge | 0001 | 15:58:13 /dev/ttyACM1 | cdc_acm | STMicroelectronics | STM32 STLink | ST-LINK/V2.1 | 0671FF535155878281151932 | 15:58:04 /dev/ttyACM3 | cdc_acm | Arduino (www.arduino.cc) | EOS High Power | Mega ADK R3 (CDC ACM) | 75230313733351110120 | 15:59:57 /dev/ttyACM2 | cdc_acm | SEGGER | J-Link | J-Link | 000683475134 | 12:41:36 ``` When the above make snippet is included as `RIOT_MAKEFILES_GLOBAL_PRE`, the serial number of the USB device is automatically set if the used board is included in the script. This will then ensure that the board debugger is used for flashing and the board serial device is used when starting the serial console. It supports command line parameters to filter by vendor name, model name, serial number, or driver. In addition, the `--most-recent` argument will only print the most recently added interface (out of those matching the filtering by vendor, model, etc.). The `--format path` argument will result in only the device path being printed for convenient use in scripts. ## Handling Multiple Boards: Simplest Approach Passing `MOST_RECENT_PORT=1` as environment variable or as parameter to make will result in the most recently connected board being preferred over the default PORT for the selected board. For some boards `TTY_BOARD_FILTER` is provided, which filters TTYs e.g. by vendor or model to only considered TTYs that actually may belong to the selected board. E.g. for Nucleo boards this is `--model 'STM32 STLink'`, as they all use an integrated STLink as programmer. As long as only one TTY is provided from an STLink, this will reliably select the correct TTY for an Nucleo regardless of which TTY was most recently connected. Some boards even provide info that allows to always reliably identify them correctly (e.g. the firmware on the ATmega16U2 used as USB to UART converter on Arduino Mega2560 will provide identification data unique to that board). ### Adding Board Filters After connecting as many variants of the board you target (and maybe some others to test that the filter actually filters out non-matching boards). Then first run `./dist/tools/usb-serial/ttys.py` without arguments and study the output. When a genuine Arduino Mega 2560, a genuine Arduino Mega ADK (a variant of the Mega 2560), a cheap Arduino Mega 2560 clone, a BBC micro:bit v2 and a Nucleo F767-ZI are connected, the following output is shown: path | driver | vendor | model | model_db | serial | ctime | iface_num -------------|---------|--------------------------|--------------------------------------|------------------------------------------------------|--------------------------------------------------|----------|---------- /dev/ttyACM0 | cdc_acm | Arduino (www.arduino.cc) | 0042 | Mega 2560 R3 (CDC ACM) | 857353134333519002C1 | 12:13:55 | 0 /dev/ttyACM1 | cdc_acm | Arduino (www.arduino.cc) | EOS High Power | Mega ADK R3 (CDC ACM) | 75230313733351110120 | 15:59:57 | 0 /dev/ttyACM2 | cdc_acm | STMicroelectronics | STM32 STLink | ST-LINK/V2.1 | 0670FF535155878281123912 | 10:00:39 | 2 /dev/ttyACM3 | cdc_acm | Arm | BBC micro:bit CMSIS-DAP | ARM mbed | 99053602000528334c41b84da1f2f09d000000006e052820 | 12:21:03 | 1 /dev/ttyUSB0 | cp210x | Silicon Labs | CP2102 USB to UART Bridge Controller | CP2102/CP2109 UART Bridge Controller [CP210x family] | 0001 | 16:57:27 | 0 Now we add arguments to the invocation of `ttys.py` to filter the list e.g. by model, vendor etc. (note: as regex!) ideally until only the target boards are listed. Some boards do not provide enough information to e.g. tell them apart from other boards using the same USB to UART bridge or the same debugger. In that case we have to live with some "bycatch". In the case of the Arduino Mega 2560 the parameters `--vendor 'Arduino' --model-db 'Mega 2560|Mega ADK'` will narrow down the list to only show the genuine Arduino Mega versions. Se we add to the `Makefile.include` in `boards/arduino-mega2560`: ```makefile TTY_BOARD_FILTER := --vendor 'Arduino' --model-db 'Mega 2560|Mega ADK' ``` Note that also matching the `R3` in `Mega 2560 R3` would prevent matching older or newer revisions than R3, so we don't add that to the regex. ### Advances Board Filters In most cases, just adding a simple `TTY_BOARD_FILTER` is sufficient. If we however have wildly different flavors of the same board (e.g. genuine Arduino Mega 2560 with an ATmega16U2 and clones with a cheap USB to UART bridge) that we all want to support, we have to instead provide a `TTY_SELECT_CMD` that prints the path to and the serial of the TTY (separated by a space) and exists with `0` if a TTY was found, or that exists with `1` and prints nothing when no TTY was found. We can still use the `ttys.py` script to detect all Arduino Mega 2560 versions: We first try to detect a genuine Arduino Mega and fall back to selecting cheap USB UART bridges when that fails using the `||` shell operator: ```makefile TTY_SELECT_CMD := $(RIOTTOOLS)/usb-serial/ttys.py \ --most-recent \ --format path serial \ --vendor 'Arduino' \ --model-db 'Mega 2560|Mega ADK' || \ $(RIOTTOOLS)/usb-serial/ttys.py \ --most-recent \ --format path serial \ --driver 'cp210x' ```