How to convert PlatformIO firmware with build offset to firmware without

Some firmwares are build with a build offset to accomodate flash space (like 32k – 0x8000) for a bootloader that is started before the firmware. One of the downsides of using such a firmware is that it always depends on a compatible bootloader to be present (compatibility is mostly defined by how much flash is allocated for the bootloader)

If you want to convert a firmware to a “normal” non-bootloader firmware, this is what you’ll have to do:

  • Set board_build.offset to 0x0 – look not only in your build configuration in platformio.ini and all included files, but also look in the configuration that your config extends, if any.
  • Set board_upload.offset_address to 0x0. This mostly affects uploading with a debugger, but you should always keep this information consistent because debugging that is a huge nightmare.
  • Edit the specific linker script your firmware is using and set the flash offset appropriately:

Look for the MEMORY section like this:

FLASH (rx)      : ORIGIN = 0x8008000, LENGTH = 512K
RAM (xrw)      : ORIGIN = 0x20000000, LENGTH = 128K

As you can see in

FLASH (rx) : ORIGIN = 0x8008000, LENGTH = 512K

the flash for this STM32 (example) is not at the MCU’s flash address 0x8000000, but at 0x8008000 – basically, the linker is told to skip the 0x8000 (32k) the bootloader occupies (else, it would overwrite the bootloader.

Change this to your MCU’s flash adress. For ARMs like the STM32, this is typically 0x8000000.

Now recompile and your firmware should work without the bootloader.

Posted by Uli Köhler in Embedded, PlatformIO, STM32

How to hide all boot text & blinking cursor on Raspberry Pi

In order to hide all the boot messages (including the terminal) and the blinking cursor on the Raspberry Pi, edit /boot/cmdline.txt and first change




After that, add the following to the end of the line:

 loglevel=3 quiet logo.nologo vt.global_cursor_default=0

Now you can reboot and enjoy the clutter-free experience.

Posted by Uli Köhler in Raspberry Pi

How to change OctoScreen minimum extrusion temperature


When trying to extrude low-temperature filaments using OctoScreen, you will see this error message:

The temperature of the hotend is too low to extrude. Please increase the temperature and try again

By default, OctoScreen has a minimum extrusion temperature of 150°C which is fine for PLA, but  for some low temperature materials you need to change the hardcoded value.

Note that setting you minimum extrusion temperature too low might damage or even destroy your extruder, if the material is not properly melted. So take caution in setting the correct value here.


Open utils/tools.go and edit this line:


Just set your desired temperature and then recompile (see the OctoScreen README on how to do that)

Note that often the firmware (like Marlin) has a separate cold extrusion prevention limit, so you need to change the limit in both OctoScreen and the firmware. For Marlin, see How to disable Marlin cold extrusion prevention via G-Code.


Posted by Uli Köhler in 3D printing, Embedded, Raspberry Pi

How to auto-reset Marlin after Kill

Under certain critical circumstances like thermal runaway protection, Marlin entered a killed state. You typically need to hard-reset the mainboard after entering that state. However, in environments where physical access to the machine, hard-resetting Marlin is not possible, so you might need to implement.

Note that diagnosing & fixing the underlying issue that caused the reset is extremely important and ignoring it might lead to further issues, up to a fire hazard or the destruction of the printer. So be sure to know what you are doing before just.

The following guide was tested with Marlin It should work with most Marlin 2.x versions with minor adjustments.

First, note that as an alternative to hard-resetting the mainboard there is the SOFT_RESET_ON_KILL option which allows you to trigger a soft reset out of kill mode using a button connected to a pin. We won’t delve into more detail on this, since it doesn’t really change the requirement for physical access to the printer.

Open Marlin/src/MarlinCore.cpp and find the minkill(bool) function.

At the end, this function contains a preprocessor-controlled branch of the following structure:

  // Branch 1 ...
  // Branch 2 ...

We will replace this entire branch by these lines:

// Wait for 5 seconds for controller to catch up
for (int i = 5000; i--;) { DELAY_US(1000); watchdog_refresh(); } // 5000*1ms = 3s
// Auto-reset after kill

I prefer to insert the 5-second delay into the reboot logic so no superordinate controller (like a Raspberry Pi running OctoPrint) can miss that the Marlin board has been killed. Although most controllers should be able to detect the killed state from the G-Code, this 5-second delay will simulate the default behaviour of not resetting at all after the killed state has been reached. However note that in case you absolutely need to reset ASAP after the kill state has been reached, it’s typically safe to omit the wait loop.

Posted by Uli Köhler in 3D printing, Embedded

Implementing STM32 DFU bootloader firmware upgrade in Marlin using M997

Marlin implements the M997 command which is intended to switch the mainboard into a firmware upgrade mode.

All STM32 variants have an integrated (hard-coded – so no need to flash it yourself) bootloader that is notoriously difficult to active.

However, Marlin implements M997 on the STM32 as just a reboot:

void flashFirmware(const int16_t) { HAL_reboot(); }

This only works if you are using a custom bootloader on your board – however, it does not use the STM32 integrated bootloader.

The following code was tested on the STM32F446 (BigTreeTech Octopus V1) but should work on any STM32 variant. It is based on previous work by Dave Hyland on StackOverflow. Replace the default flashFirmware() function in Marlin/src/HAL/STM32/HAL.cpp

void flashFirmware(const int16_t) {


    // arm-none-eabi-gcc 4.9.0 does not correctly inline this
    // MSP function, so we write it out explicitly here.
    //__set_MSP(*((uint32_t*) 0x00000000));
    __ASM volatile ("movs r3, #0\nldr r3, [r3, #0]\nMSR msp, r3\n" : : : "r3", "sp");

    ((void (*)(void)) *((uint32_t*) 0x00000004))();

    // This will never be executed

Note that we left a HAL_reboot() call as a safeguard at the end, just in case the previous calls fail.

On my BigTreeTech Octopus V1 (STM32F446), by using this code, you can successfully enter the integrated DFU bootloader.

Also see our previous posts on how to use the STM32 in DFU bootloader mode:

Posted by Uli Köhler in 3D printing, C/C++, STM32

How to flash STM32 PlatformIO firmware using dfu-util

First, you need to find the correct firmware file. dfu-util will flash firmware.bin, not firmware.elf. You can find firmware.bin in


inside your project folder. [PROFILE_NAME] is the name of the build profile you’re using, i.e. the name of the section in platformio.ini. For example:


Now flash using dfu-util:

dfu-util -a 0 -D .pio/build/PROFILE_NAME/firmware.bin -s 0x08000000


  • -a 0. The STM32 appears as four different devices in dfu-util (see dfu-util --list): The flash, option bytes, RAM etc each appear as a separate device. We only care about the flash device, which is always the first (index 0) of those devices, at least in every board I have seen so far
  • -D [filename]Download the firmware to the device
  • -s 0x08000000: Flash at address 0x08000000 which is the address of the STM32 flash.
Posted by Uli Köhler in Embedded, PlatformIO, STM32

How to exit/reset STM32 DFU bootloader

Both dfu-util and dfu-tool can flash firmware, but their current versions can’t reset the STM32 from DFU mode to run the application.

I found that using MicroPython’s pydfu.py is able to reset the. Note that currently I use pydfu.py only for resetting, not for flashing (but that might change in the future).

Download using

wget https://raw.githubusercontent.com/micropython/micropython/master/tools/pydfu.py

Install the PyUSB dependency using

sudo pip3 install pyusb

And then reset the STM32 in DFU mode:

python3 pydfu.py -x


Posted by Uli Köhler in STM32

How to fix ‘command not found: pio’ even though PlatformIO is installed


You have installed PlatformIO on your computer using Visual Studio code, however when you try to run it in your terminal/shell, you see:

$ pio
zsh: command not found: pio


PlatformIO is installed in $HOME/.platformio, but not added to the PATH environment variable, so your terminal can’t find it. Add it using

echo "export PATH=\$PATH:/home/${USER}/.platformio/penv/bin" >> ~/.profile

and then logout from your current session and log back in again (or reboot) in order for the changes to take effect. After that, you can run pio from any shell.

Posted by Uli Köhler in Linux, PlatformIO

How to fix pio remote agent start: You are not authorized! Please log in to PlatformIO Account.


When running

pio remote agent start

you see an error message like

2021-10-05 17:37:23 [info] Name: Raspberry Pi
2021-10-05 17:37:23 [info] Connecting to PlatformIO Remote Development Cloud                                                                    
2021-10-05 17:37:23 [info] Successfully connected
2021-10-05 17:37:23 [info] Authenticating
2021-10-05 17:37:23 [error] You are not authorized! Please log in to PlatformIO Account.                                                        
2021-10-05 17:37:23 [info] Successfully disconnected


You need to login to your PlatformIO account. Run

pio account login

which will prompt you for your username & password. If you don’t have an account, register using

pio account register
Posted by Uli Köhler in PlatformIO

How to fix pio remote agent start: error: can’t find Rust compiler


When running pio remote agent start, while PlatformIO installs the Python packages, you see an error log like

  generating cffi module 'build/temp.linux-armv7l-3.7/_openssl.c'                                                                                                           
  creating build/temp.linux-armv7l-3.7                                                                                                                                      
  running build_rust                                                                                                                                                        
      =============================DEBUG ASSISTANCE=============================                                                                                            
      If you are seeing a compilation error please try the following steps to                                                                                               
      successfully install cryptography:                                                                                                                                    
      1) Upgrade to the latest pip and try again. This will fix errors for most                                                                                             
         users. See: https://pip.pypa.io/en/stable/installing/#upgrading-pip                                                                                                
      2) Read https://cryptography.io/en/latest/installation/ for specific                                                                                                  
         instructions for your platform.                                                                                                                                    
      3) Check our frequently asked questions for more information:                                                                                                         
      4) Ensure you have a recent Rust toolchain installed:                                                                                                                 
      Python: 3.7.3                                                                                                                                                         
      platform: Linux-5.10.60-v7l+-armv7l-with-debian-10.10                                                                                                                 
      pip: n/a                                                                                                                                                              
      setuptools: 58.2.0                                                                                                                                                    
      setuptools_rust: 0.12.1                                                                                                                                               
      =============================DEBUG ASSISTANCE=============================                                                                                            
  error: can't find Rust compiler                                                                                                                                           
  If you are using an outdated pip version, it is possible a prebuilt wheel is available for this package but pip is not able to install from it. Installing from the wheel would avoid the need for a Rust compiler.                                                                                                                                   
  To update pip, run:                                                                                                                                                       
      pip install --upgrade pip                                                                                                                                             
  and then retry package installation.                                                                                                                                      
  If you did intend to build this package from source, try installing a Rust compiler from your system package manager and ensure it is on the PATH during installation. Alternatively, rustup (available at https://rustup.rs) is the recommended way to download and update the Rust compiler toolchain.                                              
  This package requires Rust >=1.41.0.                                                                                                                                      
  ERROR: Failed building wheel for cryptography
Successfully built pyopenssl
Failed to build cryptography
ERROR: Could not build wheels for cryptography which use PEP 517 and cannot be installed directly
Error: Traceback (most recent call last):
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/platformio/package/manager/core.py", line 127, in inject_contrib_pysite                                       
    from OpenSSL import SSL                                                                                                                                                 
  File "/home/pi/.platformio/packages/contrib-pysite/OpenSSL/__init__.py", line 8, in <module>                                                                              
  File "/home/pi/.platformio/packages/contrib-pysite/OpenSSL/crypto.py", line 12, in <module>                                                                               
  File "/home/pi/.platformio/packages/contrib-pysite/cryptography/x509/__init__.py", line 8, in <module>                                                                    
  File "/home/pi/.platformio/packages/contrib-pysite/cryptography/x509/base.py", line 18, in <module>                                                                       
  File "/home/pi/.platformio/packages/contrib-pysite/cryptography/x509/extensions.py", line 20, in <module>                                                                 
  File "/home/pi/.platformio/packages/contrib-pysite/cryptography/hazmat/primitives/constant_time.py", line 11, in <module>                                                 
ImportError: /home/pi/.platformio/packages/contrib-pysite/cryptography/hazmat/bindings/_constant_time.abi3.so: cannot open shared object file: No such file or directory    

During handling of the above exception, another exception occurred:                                                                                                         

Traceback (most recent call last):                                                                                                                                          
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/platformio/__main__.py", line 115, in main                                                                    
    cli()  # pylint: disable=no-value-for-parameter                                                                                                                         
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/click/core.py", line 1137, in __call__                                                                        
    return self.main(*args, **kwargs)                                                                                                                                       
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/click/core.py", line 1062, in main                                                                            
    rv = self.invoke(ctx)                                                                                                                                                   
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/platformio/commands/__init__.py", line 44, in invoke                                                          
    return super(PlatformioCLI, self).invoke(ctx)                                                                                                                           
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/click/core.py", line 1668, in invoke                                                                          
    return _process_result(sub_ctx.command.invoke(sub_ctx))                                                                                                                 
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/click/core.py", line 1665, in invoke                                                                          
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/click/core.py", line 1404, in invoke                                                                          
    return ctx.invoke(self.callback, **ctx.params)                                                                                                                          
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/click/core.py", line 763, in invoke                                                                           
    return __callback(*args, **kwargs)                                                                                                                                      
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/click/decorators.py", line 26, in new_func                                                                    
    return f(get_current_context(), *args, **kwargs)                                                                                                                        
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/platformio/commands/remote/command.py", line 40, in cli                                                       
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/platformio/package/manager/core.py", line 129, in inject_contrib_pysite                                       
  File "/home/pi/.platformio/penv/lib/python3.7/site-packages/platformio/package/manager/core.py", line 156, in build_contrib_pysite_package
    subprocess.check_call(args + [dep])
  File "/usr/lib/python3.7/subprocess.py", line 347, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['/home/pi/.platformio/penv/bin/python', '-m', 'pip', 'install', '--no-compile', '-t', '/home/pi/.platformio/packages/contrib-pysite', '--no-binary', ':all:', 'pyopenssl >= 16.0.0']' returned non-zero exit status 1.


An unexpected error occurred. Further steps:

* Verify that you have the latest version of PlatformIO using
  `pip install -U platformio` command

* Try to find answer in FAQ Troubleshooting section

* Report this problem to the developers



You need to install rust using

sudo apt -y install rustc

and then run the original command again:

pio remote agent start


Posted by Uli Köhler in PlatformIO

How to install PlatformIO remote agent on Raspberry Pi

This is from the Super Quick installation procedure from the official PlatformIO documentation:

python3 -c "$(curl -fsSL https://raw.githubusercontent.com/platformio/platformio/master/scripts/get-platformio.py)"
sudo apt -y install rustc
echo "export PATH=\$PATH:/home/${USER}/.platformio/penv/bin" >> ~/.profile

Run it as user (whatever user you want to use PlatformIO as – by default, this is the pi user) and not as root!

After running these commands, log out and log back in again in order for the changes to the PATH environment variable to take effect.

After logging in, you can use pio from the shell:

$ pio

Usage: pio [OPTIONS] COMMAND [ARGS]...

  --version          Show the version and exit.
  -f, --force        DEPRECATE
  -c, --caller TEXT  Caller ID (service)
  --no-ansi          Do not print ANSI control characters
  -h, --help         Show this message and exit.

  access    Manage resource access
  account   Manage PlatformIO account
  boards    Embedded board explorer
  check     Static code analysis
  ci        Continuous integration
  debug     Unified debugger
  device    Device manager & serial/socket monitor
  home      GUI to manage PlatformIO
  lib       Library manager
  org       Manage organizations
  package   Package manager
  platform  Platform manager
  project   Project manager
  remote    Remote development
  run       Run project targets (build, upload, clean, etc.)
  settings  Manage system settings
  system    Miscellaneous system commands
  team      Manage organization teams
  test      Unit testing
  update    Update installed platforms, packages and libraries
  upgrade   Upgrade PlatformIO to the latest version


Posted by Uli Köhler in PlatformIO, Raspberry Pi

How to flash Marlin on BigTreeTech Octopus V1 using debug adapter

In order to flash the Bigtreetech Octopus V1 using my STLinkv2 debug adapter, I needed. First we need to note that the first 32k of flash memory are occupied by the bootloader (0x08000000 to 0x08008000). So we need to flash the firmware at address 0x08008000. By default, this is not configured correctly in Marlin.

Open ini/stm32f4.ini and edit the [env:BIGTREE_OCTOPUS_V1]:

platform           = ${common_stm32.platform}
extends            = stm32_variant
board              = marlin_BigTree_Octopus_v1
board_build.offset = 0x8000
board_upload.offset_address = 0x08008000
build_flags        = ${stm32_variant.build_flags}
                     -DSTM32F446_5VX -DUSE_USB_HS_IN_FS
upload_protocol = stlink

Note that you absolutely need to re-flash the bootloader in case you accidentally flashed with the old configuration. Follow the official documentation in order to flash the bootloader. I flash usin STM32CubeProgrammer 2.7.0 (2.8.0 does not work) on both Linux and Windows.

The [env:BIGTREE_OCTOPUS_V1_USB] will be updated automatically as it includes [env:BIGTREE_OCTOPUS_V1]

Posted by Uli Köhler in 3D printing, Electronics, STM32

ESP32 JTAG pinout

The ESP32 uses the following pins for JTAG:

  • GPIO12: TDI
  • GPIO13: TCK
  • GPIO14: TMS
  • GPIO15: TDO

Source: ESP32 reference manual, section 4.10 IO_MUX Pad List

Posted by Uli Köhler in ESP8266/ESP32

What is the default PlatformIO / Arduino ESP32 TIMER_BASE_CLK?

On PlatformIO / Arduino, by default the TIMER_BASE_CLK is 80 MHz (the maximum frequency the ESP32 can run at).

If you want to verify this yourself, use this firmware:

#include <Arduino.h>

void setup() {

void loop() {


Posted by Uli Köhler in Arduino, Electronics, Embedded, ESP8266/ESP32, PlatformIO

How to fix PlatformIO serial monitor scrambled output


When using the Monitor function of platformIO, you see strange characters instead of strings being printed, for example:



This issue almost always appears due to the Monitor function using the wrong UART speed. You can see from the log in our screenshot above:

--- Miniterm on /dev/ttyUSB0  9600,8,N,1 ---

that PlatformIO is using 9600 baud in this case – but your microcontroller is sending data at a faster speed (or, rarely at a slower speed).

Most firmwares using serial IO use 115200 baud, so that’s what I’d recommend to try first, but if that doesn’t work, look out for config options named baud rate or similar, or for lines of code like


in the firmware.

In order to change the Monitor UART speed, open platformio.ini and add

monitor_speed = 115200

Full platformio.ini example for ESP32:

platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200

After that, restart the Monitor function.

Posted by Uli Köhler in Arduino, Electronics, Embedded, ESP8266/ESP32, PlatformIO, STM32

How to fix ESP32 PlatformIO error: ‘LED_BUILTIN’ was not declared in this scope


When trying to compile your ESP32 firmware using PlatformIO, you see this error message:

src/main.cpp: In function 'void setup()':
src/main.cpp:22:13: error: 'LED_BUILTIN' was not declared in this scope
     pinMode(LED_BUILTIN, OUTPUT);


Important: Some ESP32 boards such as the ESP32-DevKitC have no builtin LED at all ! Either connect an external LED or find another method of doing whatever you are intending to do.

On most ESP32 boards that do have a builtin LED, the LED is connected to pin 2 – however, PlatformIO does not define LED_BUILTIN p. In order to fix the issue, define LED_BUILTIN yourself by using

#define LED_BUILTIN 2

at the top of every file where you see this error.

Posted by Uli Köhler in Electronics, Embedded, ESP8266/ESP32, PlatformIO

How to fix Linux ESP32 PlatformIO PermissionError: [Errno 13] Permission denied: ‘/dev/ttyUSB0’


When trying to flash a ESP8266 or ESP32 board on Linux, you see an error message like

Warning! Please install `99-platformio-udev.rules`. 
More details: https://docs.platformio.org/page/faq.html#platformio-udev-rules

Auto-detected: /dev/ttyUSB0
Uploading .pio/build/esp32dev/firmware.bin
esptool.py v3.1
Serial port /dev/ttyUSB0
Traceback (most recent call last):
  File "/home/uli/.platformio/penv/lib/python3.8/site-packages/serial/serialposix.py", line 322, in open
    self.fd = os.open(self.portstr, os.O_RDWR | os.O_NOCTTY | os.O_NONBLOCK)
PermissionError: [Errno 13] Permission denied: '/dev/ttyUSB0'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/uli/.platformio/packages/tool-esptoolpy/esptool.py", line 4582, in <module>
  File "/home/uli/.platformio/packages/tool-esptoolpy/esptool.py", line 4575, in _main
  File "/home/uli/.platformio/packages/tool-esptoolpy/esptool.py", line 4074, in main
    esp = esp or get_default_connected_device(ser_list, port=args.port, connect_attempts=args.connect_attempts,
  File "/home/uli/.platformio/packages/tool-esptoolpy/esptool.py", line 120, in get_default_connected_device
    _esp = chip_class(each_port, initial_baud, trace)
  File "/home/uli/.platformio/packages/tool-esptoolpy/esptool.py", line 313, in __init__
    self._port = serial.serial_for_url(port)
  File "/home/uli/.platformio/penv/lib/python3.8/site-packages/serial/__init__.py", line 90, in serial_for_url
  File "/home/uli/.platformio/penv/lib/python3.8/site-packages/serial/serialposix.py", line 325, in open
    raise SerialException(msg.errno, "could not open port {}: {}".format(self._port, msg))
serial.serialutil.SerialException: [Errno 13] could not open port /dev/ttyUSB0: [Errno 13] Permission denied: '/dev/ttyUSB0'


As described at the top of the error message, install the PlatformIO udev rules:

curl -fsSL https://raw.githubusercontent.com/platformio/platformio-core/master/scripts/99-platformio-udev.rules | sudo tee /etc/udev/rules.d/99-platformio-udev.rules

then restart udev:

sudo systemctl restart udev

After that, unplug an re-plug your ESP32 board in order for the changes to take effect

Additionally, I recommend adding your user to the dialout group – the Linux group that owns most USB devices:

sudo usermod -a -G dialout $USER

In order for the changes to take effect, log out from your current session completely and log back in again (or reboot). While not strictly neccessary in order to fix this specific error message, it helps in preventing future USB permission issues.

Posted by Uli Köhler in Electronics, Embedded, ESP8266/ESP32, PlatformIO