Console echo

Overview

This example shows how the console_getchar() and console_putchar() functions can be used to echo an input character back to the console.

Requirements

UART console is required to run this sample.

Building and Running

Build and flash the sample as follows, changing nucleo_f401re for your board. Alternatively you can run this using QEMU, as described in console_getchar().

west build -b nucleo_f401re samples/subsys/console/echo
west flash

Following the initial prompt given by the firmware, start pressing keys on a keyboard, and they will be echoed back to the terminal program you are using.

Running on QEMU

On QEMU you can use the VIRTIO console device. It is already configured in Zephyr. To use it, run:

west build -b qemu_x86_64 samples/subsys/console/echo -- -DDTC_OVERLAY_FILE=virtconsole.overlay -DEXTRA_CONF_FILE=overlay-virtconsole.conf
west build -t run

It is possible to use multiple inputs/outputs at once by configuring them in the overlay-virtconsole.conf file.

Add CONFIG_UART_VIRTIO_CONSOLE_F_MULTIPORT=y to enable the multiport feature.
Configure more ports using the CONFIG_QEMU_EXTRA_FLAGS option. Refer to the QEMU manual for details.

Sample Output

You should see another line with instructions below. If not,
the (interrupt-driven) console device doesn't work as expected:
Start typing characters to see them echoed back