.. _lpuart_sample: Low Power UART ############## .. contents:: :local: :depth: 2 The Low Power UART sample demonstrates the capabilities of the :ref:`uart_nrf_sw_lpuart` module. Requirements ************ The sample supports the following development kits: .. table-from-sample-yaml:: .. include:: /includes/tfm.txt The sample also requires the following pins to be shorted: * TX (Arduino Digital Pin 10 (4 on nRF21540 DK)) with RX (Arduino Digital Pin 11 (5 on nRF21540 DK)) * Request Pin (Arduino Digital Pin 12 (6 on nRF21540 DK)) with Response Pin (Arduino Digital Pin 13 (7 on nRF21540 DK)) Additionally, it requires a logic analyzer. Overview ******** The sample implements a simple loopback using a single UART instance. By default, the console and logging are disabled to demonstrate low power consumption when UART is active. Configuration ************* |config| FEM support =========== .. include:: /includes/sample_fem_support.txt Building and running ******************** .. |sample path| replace:: :file:`samples/peripheral/lpuart` .. include:: /includes/build_and_run_ns.txt Testing ======= After programming the sample to your development kit, test it by performing the following steps: 1. Connect the logic analyzer to the shorted pins, to confirm UART activity. 2. Measure the current to confirm that the power consumption indicates that high-frequency clock is disabled during the idle stage. During the idle stage, the UART receiver is ready to start reception, as the request pin wakes it up. Dependencies ************ This sample uses the following |NCS| driver: * :ref:`uart_nrf_sw_lpuart` In addition, it uses the following Zephyr libraries: * :ref:`zephyr:device_model_api` * :ref:`zephyr:logging_api` The sample also uses the following secure firmware component: * :ref:`Trusted Firmware-M `