.. zephyr:code-sample:: so_txtime :name: UDP sender using SO_TXTIME :relevant-api: bsd_sockets ethernet Control the transmission time of a packet using SO_TXTIME socket option. Overview ******** This sample is a simple UDP sender/receiver which will set the SO_TXTIME socket option and expects the Ethernet driver to send the data when the TX time is expected. The application requires that the board has PTP clock support. A simulated PTP clock is provided for qemu_x86 board. Also frdm_k64f and sam_e70_xplained boards are supported. Other mcux or gmac Ethernet driver based boards should work too. User can control how long the application should wait between packets sent by setting :kconfig:option:`CONFIG_NET_SAMPLE_PACKET_INTERVAL` option. Also the TXTIME value can be specified in the config file by setting the :kconfig:option:`CONFIG_NET_SAMPLE_PACKET_TXTIME` option. In this case the value is used as an offset from the current time. Building and Running ******************** When the application is run, it starts to send UDP packets. You can start ``echo-server`` application from `net-tools`_ project to catch these and send the data back to this application. Optionally you can set :kconfig:option:`CONFIG_NET_SAMPLE_PACKET_SOCKET` option, which makes the application to create an ``AF_PACKET`` type socket. In this case, the ``echo-server`` application cannot be used as a peer. This sample can be built and executed on qemu_x86 board as described in :ref:`networking_with_host`. .. _`net-tools`: https://github.com/zephyrproject-rtos/net-tools