samples: drivers: Add auxdisplay_digits sample

This commit introduces a new sample for the Auxiliary display driver.

The sample demonstrates counting from 0 to 1000, with an interval of 100ms
between each increment.

This sample primarily serves to demonstrate the capabilities of segment
displays.

Signed-off-by: Chen Xingyu <hi@xingrz.me>

samples/drivers/auxdisplay_digits/CMakeLists.txt

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr HINTS $ENV{ZEPHYR_BASE})
+project(auxdisplay_digits)
+
+target_sources(app PRIVATE src/main.c)

samples/drivers/auxdisplay_digits/README.rst

@@ -0,0 +1,33 @@
+.. zephyr:code-sample:: auxdisplay_digits
+   :name: Auxiliary digits display
+   :relevant-api: auxdisplay_interface
+
+   Output increasing numbers to an auxiliary display.
+
+Overview
+********
+
+This sample demonstrates the use of the
+:ref:`auxiliary display driver <auxdisplay_api>` for digit-based displays, such
+as 7-segment displays.
+
+Building and Running
+********************
+
+Note that this sample requires a board with a 7-segment display setup. You can
+build your own setup by fly-wiring a 7-segment display to any board you have.
+
+A sample overlay is provided for the ``native_sim`` target. See the overlay file
+:zephyr_file:`samples/drivers/auxdisplay_digits/boards/native_sim.overlay` for a
+demonstration.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/drivers/auxdisplay_digits
+   :host-os: unix
+   :board: native_sim
+   :goals: build
+   :compact:
+
+If successful, the display first lights up all segments (e.g., 8.8.8. on a
+3-digit display), blinks once, sequentially lights up each digit from left to
+right, and then counts up from 0 to the maximum number that can be displayed.

samples/drivers/auxdisplay_digits/boards/native_sim.conf

@@ -0,0 +1 @@
+CONFIG_GPIO=y

samples/drivers/auxdisplay_digits/boards/native_sim.overlay

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2024-2025 Chen Xingyu <hi@xingrz.me>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&gpio0 {
+	ngpios = <11>;
+};
+
+/ {
+	auxdisplay_0: auxdisplay {
+		compatible = "gpio-7-segment";
+		status = "okay";
+		columns = <3>;
+		rows = <1>;
+		segment-gpios = <&gpio0 0 0>,  /* A */
+				<&gpio0 1 0>,  /* B */
+				<&gpio0 2 0>,  /* C */
+				<&gpio0 3 0>,  /* D */
+				<&gpio0 4 0>,  /* E */
+				<&gpio0 5 0>,  /* F */
+				<&gpio0 6 0>,  /* G */
+				<&gpio0 7 0>;  /* DP */
+		digit-gpios = <&gpio0  8 0>,  /* DIG1 */
+			      <&gpio0  9 0>,  /* DIG2 */
+			      <&gpio0 10 0>;  /* DIG3 */
+		refresh-period-ms = <1>;
+	};
+};

samples/drivers/auxdisplay_digits/prj.conf

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+CONFIG_AUXDISPLAY=y
+CONFIG_LOG=y

samples/drivers/auxdisplay_digits/sample.yaml

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+sample:
+  description: Demonstration of auxdisplay driver for segment displays
+  name: Auxiliary (segment) display sample
+tests:
+  sample.drivers.auxdisplay_digits:
+    tags: auxdisplay
+    platform_allow:
+      - native_sim
+    integration_platforms:
+      - native_sim
+    build_only: true

samples/drivers/auxdisplay_digits/src/main.c

@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2023 Jamie McCrae
+ * Copyright (c) 2024-2025 Chen Xingyu <hi@xingrz.me>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+#include <zephyr/kernel.h>
+#include <zephyr/device.h>
+#include <zephyr/drivers/auxdisplay.h>
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_REGISTER(auxdisplay_sample, LOG_LEVEL_DBG);
+
+#define AUXDISPLAY_NODE        DT_NODELABEL(auxdisplay_0)
+#define AUXDISPLAY_DIGIT_COUNT DT_PROP_LEN(AUXDISPLAY_NODE, digit_gpios)
+
+static const struct device *const dev = DEVICE_DT_GET(AUXDISPLAY_NODE);
+static uint8_t data[AUXDISPLAY_DIGIT_COUNT * 2];
+
+int main(void)
+{
+	int rc;
+	int i, len;
+
+	if (!device_is_ready(dev)) {
+		LOG_ERR("Auxdisplay device is not ready.");
+		return -ENODEV;
+	}
+
+	/* Light up all segments */
+	for (i = 0; i < AUXDISPLAY_DIGIT_COUNT; i++) {
+		data[i * 2] = '8';
+		data[i * 2 + 1] = '.';
+	}
+	rc = auxdisplay_write(dev, data, strlen(data));
+	if (rc != 0) {
+		LOG_ERR("Failed to write data: %d", rc);
+		return rc;
+	}
+
+	k_msleep(500);
+
+	/* Blinks it once */
+
+	rc = auxdisplay_display_off(dev);
+	if (rc != 0) {
+		LOG_ERR("Failed to turn display off: %d", rc);
+		return rc;
+	}
+
+	k_msleep(500);
+
+	rc = auxdisplay_display_on(dev);
+	if (rc != 0) {
+		LOG_ERR("Failed to turn display on: %d", rc);
+		return rc;
+	}
+
+	k_msleep(500);
+
+	/* Clear the display */
+
+	rc = auxdisplay_clear(dev);
+	if (rc != 0) {
+		LOG_ERR("Failed to clear display: %d", rc);
+		return rc;
+	}
+
+	k_msleep(500);
+
+	/* Test cursor movement by filling each digit with a number */
+
+	for (i = 0; i < AUXDISPLAY_DIGIT_COUNT; i++) {
+		snprintf(data, sizeof(data), "%d", i);
+		rc = auxdisplay_write(dev, data, strlen(data));
+		if (rc != 0) {
+			LOG_ERR("Failed to write data: %d", rc);
+			return rc;
+		}
+
+		k_msleep(500);
+	}
+
+	k_msleep(500);
+
+	/* Count from 0 up to fill all digits */
+
+	for (i = 0;; i = (i + 1) % (int)pow(10, AUXDISPLAY_DIGIT_COUNT)) {
+		snprintk(data, sizeof(data), "%d", i);
+		len = strlen(data);
+
+		rc = auxdisplay_clear(dev);
+		if (rc != 0) {
+			LOG_ERR("Failed to clear display: %d", rc);
+			return rc;
+		}
+
+		/* Right-align the number */
+		rc = auxdisplay_cursor_position_set(dev, AUXDISPLAY_POSITION_ABSOLUTE,
+						    AUXDISPLAY_DIGIT_COUNT - len, 0);
+		if (rc != 0) {
+			LOG_ERR("Failed to set cursor position: %d", rc);
+			return rc;
+		}
+
+		rc = auxdisplay_write(dev, data, len);
+		if (rc != 0) {
+			LOG_ERR("Failed to write data: %d", rc);
+			return rc;
+		}
+
+		k_msleep(100);
+	}
+
+	return 0;
+}