This is a flexPTP demo project showcasing the capabilities of the flexPTP IEEE 1588 Precision Time Protocol implementation for the NXP FRDM-K64F Kinetis devboard.
Still not clear what is it useful for? No worries, it's a behind-the-scenes support technology that use unaware every day if you have a smartphone or when you are connected to the internet. Modern telecommunication and measurement systems often rely on precise time synchronization down to the nanoseconds' scale. Methods got standardized by the IEEE and now it's known by the name of the Precision Time Protocol. This software project is an evaluation environment to showcase the capabilities of our IEEE 1588 PTP implementation named flexPTP on the STMicroelectronics NXP FRDM-K64F Kinetis board.
Tip
Just want to try the demo and skip compiling? Download one of the precompiled binaries and jump to Deploying!
Note
To acquire the full source tree after cloning the repo, please fetch the linked submodules as well:
git clone https://github.com/epagris/flexPTP-demo-FRDM-K64F
cd flexPTP-demo-FRDM-K64F
git submodule init
git submodule update
The following two pieces of software are necessary for building:
arm-none-eabi-gcc(v12+): the GCC ARM Cortex-M C cross-compilercmake(v3.15+): KitWare's build management system
Note
Both applications are available on common Linux systems through the official package repository. For building on Windows, install the ARM GNU toolchain and CMake.
The project relies on the NXP MCUXpresso SDK. The SDK's root dir must be exported through the MCUXSDK environmental variable so that CMake can reference it using $ENV{MCUXSDK}. Alternatively, set the path using the MCUXDSK variable on the command line during CMake configuration time (-DMCUXSDK=...).
The project is fully CMake managed. Configure and invoke the cross-compiler using the commands below:
cmake . -B build -DCMAKE_TOOLCHAIN_FILE=arm-none-eabi-gcc.cmake
cmake --build build --target flexptp-demo --
Once the building has concluded the output binaries would be deposited in the build directory: flexptp-demo.elf, flexptp-demo.hex
The compiled binaries can be downloaded onto the devboard through several tools:
The OpenOCD programming/debugging tool can also be used to upload the firmware using the following command:
openocd -f "board/nxp_frdm-k64f.cfg" -c init -c halt -c "program build/flexptp-demo.elf reset exit"
OpenOCD is also available through the common Linux package managers.
To download and debug the firmware using the MCUXpresso VSCode extension features configure the respective path variables. To learn more, read the development section.
The firmware prints its messages to and expect user input coming on the board controller's virtual serial port using the 115200-8-N-1 configuration. Use Putty or any equivalent (e.g. GtkTerm) serial port terminal to communicate with the firmware. On Linux, the device will show up as /dev/ttyACMx.
Note
Read the firmware's bootup hints and messages carefully!
The 1PPS signal is emitted on the PTC16 pin (FRDM-K64F: J1, pin 2). The PTC17 pin (FRDM-K64F: J1, pin 4) is configured to capture and timestamp rising edges on the pin with the PTP clock. Captured timestamps will be printed in the following form: Capture: 1753433377.203422580.
To test the software and evaluate the synchronization accuracy connect the devboard with another PTP-compatible equipment, either a dedicated Master clock or any other device (e.g. another devboard). We recommend using the linuxptp software suite available in Linux systems through the official package repositories, PTP hardware support is available out-of-the-box on several Intel NICs, like Intel I210, Intel I219-V or Intel 82576.
An all-around Visual Studio Code project is packaged along the project to enable easy development, debugging and editing. To enable these powerful features, install the MCUXpresso, CMakeTools, Cortex-Debug, Embedded Tools extensions, and the OpenOCD tool.
To harness NXP's proprietary fast programming and debugging features set the toolchainPath and path fields in the .vscode/mcuxpresso-tools.json file accordingly. clangd and clang-format are highly recommended.
Thas project has predefined Launch and Attach tasks.
The project is relying on the following large software building blocks:
- the FreeRTOS embedded operating system (shipped by the MCUXpresso SDK),
- the CMSIS RTOS V2 module as a wrapper for FreeRTOS,
- the Lightweight IP (lwip) Ethernet stack extended with PTP timestamp support (shipped by the MCUXpresso SDK),
- the embfmt a printf()-like formatted printer implementation for embedded systems.
The project is organized the following way:
ROOT
Drivers
eth_custom: a custom Ethernet driver (with PTP timestamp support) based on the `enet_ethernetif_kinetis.c` driver
Inc: headers for compile-time library configuration
Modules
flexPTP and flexPTP_port: our PTP implementation (submodule) and the MK64F platform driver
embfmt: a printf()-like formatted printer implementation for embedded systems (submodule)
Src
CMSIS-RTOS: ARM CMSIS-RTOS2 related files
standard_output: MSG() <-> UART redirection
ethernet_lwip.c/h: Ethernet stack initialization
cli.c/h CLI-interface implementation
cmds.c: custom CLI commands
Note
The flexPTP parameters are defined in the flexptp_options.h header.
In this project the memory-heavy printf() is replaced by the more embedded-optimized MSG() function backed by the embfmt library. Parameters and format specifiers are fully printf() compatible.
The software offers you with the following multitude, most flexPTP-related of commands:
? Print this help (22/48)
hist Print command history
osinfo Print OS-related information
flexptp Start flexPTP daemon
ptp pps {freq} Set or query PPS signal frequency [Hz]
ptp servo params [Kp Kd] Set or query K_p and K_d servo parameters
ptp servo log internals {on|off} Enable or disable logging of servo internals
ptp reset Reset PTP subsystem
ptp servo offset [offset_ns] Set or query clock offset
ptp log {def|corr|ts|info|locked|bmca} {on|off} Turn on or off logging
time [ns] Print time
ptp master [[un]prefer] [clockid] Master clock settings
ptp info Print PTP info
ptp domain [domain] Print or set PTP domain
ptp tuning [tuning] Print or set tuning in PPB
ptp transport [{ipv4|802.3}] Set or get PTP transport layer
ptp delmech [{e2e|p2p}] Set or get PTP delay mechanism
ptp transpec [{def|gPTP}] Set or get PTP transportSpecific field (majorSdoId)
ptp profile [preset [<name>]] Print or set PTP profile, or list available presets
ptp tlv [preset [name]|unload] Print or set TLV-chain, or list available TLV presets
ptp pflags [<flags>] Print or set profile flags
ptp period <delreq|sync|ann> [<lp>|matched] Print or set log. periods
ptp coarse [threshold] Print or set coarse correction threshold
ptp priority [<p1> <p2>] Print or set clock priority fields
Tip
The above hint can be listed by typing '?'.
Time Synchronization Extension for the IO-Link Industrial Communication Protocol
Methods of Peripheral Synchronization in Real-Time Cyber-Physical Systems
The project was created by András Wiesner (Epagris) in 2025 and published under the MIT license. Contributions are welcome! :)