A debug probe is special hardware which allows you to control execution of a Zephyr application running on a separate board. Debug probes usually allow reading and writing registers and memory, and support breakpoint debugging of the Zephyr application on your host workstation using tools like GDB. They may also support other debug software and more advanced features such as tracing program execution <tracing>. For details on the related host software supported by Zephyr, see debug-host-tools.
Debug probes are usually connected to your host workstation via USB; they are sometimes also accessible via an IP network or other means. They usually connect to the device running Zephyr using the JTAG or SWD protocols. Debug probes are either separate hardware devices or circuitry integrated into the same board which runs Zephyr.
Many supported boards in Zephyr include a second microcontroller that serves as an onboard debug probe, usb-to-serial adapter, and sometimes a drag-and-drop flash programmer. This eliminates the need to purchase an external debug probe and provides a variety of debug host tool options.
Several hardware vendors have their own branded onboard debug probe implementations: NXP LPC boards have LPC-Link2, NXP Kinetis (former Freescale) boards have OpenSDA, and ST boards have ST-LINK. Each onboard debug probe microcontroller can support one or more types of firmware that communicate with their respective debug host tools. For example, an OpenSDA microcontroller can be programmed with DAPLink firmware to communicate with pyOCD or OpenOCD debug host tools, or with J-Link firmware to communicate with J-Link debug host tools.
Some supported boards in Zephyr do not include an onboard debug probe and therefore require an external debug probe. In addition, boards that do include an onboard debug probe often also have an SWD or JTAG header to enable the use of an external debug probe instead. One reason this may be useful is that the onboard debug probe may have limitations, such as lack of support for advanced debuggers or high-speed tracing. You may need to adjust jumpers to prevent the onboard debug probe from interfering with the external debug probe.
The LPC-Link2 J-Link is an onboard debug probe and usb-to-serial adapter supported on many NXP LPC and i.MX RT development boards.
This debug probe is compatible with the following debug host tools:
jlink-debug-host-tools
This probe is realized by programming the LPC-Link2 microcontroller with J-Link LPC-Link2 firmware. Download and install LPCScrypt to get the firmware and programming scripts.
- Put the LPC-Link2 microcontroller into DFU boot mode by attaching the DFU jumper, then powering up the board.
- Run the
program_JLINKscript. - Remove the DFU jumper and power cycle the board.
The OpenSDA DAPLink is an onboard debug probe and usb-to-serial adapter supported on many NXP Kinetis and i.MX RT development boards. It also includes drag-and-drop flash programming support.
This debug probe is compatible with the following debug host tools:
pyocd-debug-host-toolsopenocd-debug-host-tools
This probe is realized by programming the OpenSDA microcontroller with DAPLink OpenSDA firmware. NXP provides OpenSDA DAPLink Board-Specific Firmwares.
Before you program the firmware, make sure to install the debug host tools first.
As with all OpenSDA debug probes, the steps for programming the firmware are:
- Put the OpenSDA microcontroller into bootloader mode by holding the reset button while you power on the board. Note that "bootloader mode" in this context applies to the OpenSDA microcontroller itself, not the target microcontroller of your Zephyr application.
- After you power on the board, release the reset button. A USB mass storage device called BOOTLOADER or MAINTENANCE will enumerate.
- Copy the OpenSDA firmware binary to the USB mass storage device.
- Power cycle the board, this time without holding the reset button. You should see three USB devices enumerate: a CDC device (serial port), a HID device (debug port), and a mass storage device (drag-and-drop flash programming).
The OpenSDA J-Link is an onboard debug probe and usb-to-serial adapter supported on many NXP Kinetis and i.MX RT development boards.
This debug probe is compatible with the following debug host tools:
jlink-debug-host-tools
This probe is realized by programming the OpenSDA microcontroller with J-Link OpenSDA firmware. Segger provides OpenSDA J-Link Generic Firmwares and OpenSDA J-Link Board-Specific Firmwares, where the latter is generally recommended when available. Board-specific firmwares are required for i.MX RT boards to support their external flash memories, whereas generic firmwares are compatible with all Kinetis boards.
Before you program the firmware, make sure to install the debug host tools first.
As with all OpenSDA debug probes, the steps for programming the firmware are:
- Put the OpenSDA microcontroller into bootloader mode by holding the reset button while you power on the board. Note that "bootloader mode" in this context applies to the OpenSDA microcontroller itself, not the target microcontroller of your Zephyr application.
- After you power on the board, release the reset button. A USB mass storage device called BOOTLOADER or MAINTENANCE will enumerate.
- Copy the OpenSDA firmware binary to the USB mass storage device.
- Power cycle the board, this time without holding the reset button. You should see two USB devices enumerate: a CDC device (serial port) and a vendor-specific device (debug port).
ST-LINK/V2-1 is a serial and debug adapter built into all Nucleo and Discovery boards. It provides a bridge between your computer (or other USB host) and the embedded target processor, which can be used for debugging, flash programming, and serial communication, all over a simple USB cable.
It is compatible with the following host debug tools:
openocd-debug-host-toolsjlink-debug-host-tools
For some STM32 based boards, it is also compatible with:
pyocd-debug-host-tools
While it works out of the box with OpenOCD, it requires some flashing to work with J-Link. To do this, SEGGER offers a firmware upgrading the ST-LINK/V2-1 on board on the Nucleo and Discovery boards. This firmware makes the ST-LINK/V2-1 compatible with J-LinkOB, allowing users to take advantage of most J-Link features like the ultra fast flash download and debugging speed or the free-to-use GDBServer.
More informations about upgrading ST-LINK/V2-1 to JLink or restore ST-Link/V2-1 firmware please visit: Segger over ST-Link
OpenOCD is available by default on ST-Link and configured as the default flash and debug tool. Flash and debug can be done as follows:
Once STLink is flashed with SEGGER FW and J-Link GDB server is installed on your host computer, you can flash and debug as follows:
Use the CMake flash target with the argument STLINK_FW=jlink to build your Zephyr application.
Use the CMake debug target with the argument STLINK_FW=jlink to build your Zephyr application, invoke the J-Link GDB server, attach a GDB client, and program your Zephyr application to flash. It will leave you at a GDB prompt.
If you configured your Zephyr application to use Segger RTT console instead, open telnet:
$ telnet localhost 19021 Trying ::1... Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. SEGGER J-Link V6.30f - Real time terminal output J-Link STLink V21 compiled Jun 26 2017 10:35:16 V1.0, SN=773895351 Process: JLinkGDBServerCLExe Zephyr Shell, Zephyr version: 1.12.99 Type 'help' for a list of available commands shell>
If you get no RTT output you might need to disable other consoles which conflict with the RTT one if they are enabled by default in the particular sample or application you are running, such as disable UART_CONSOLE in menucon
Segger J-Link is a family of external debug probes, including J-Link EDU, J-Link PLUS, J-Link ULTRA+, and J-Link PRO, that support a large number of devices from different hardware architectures and vendors.
This debug probe is compatible with the following debug host tools:
jlink-debug-host-toolsopenocd-debug-host-tools
Before you use this debug probe, make sure to install the debug host tools first.