examples: add simple skald_bthome example

examples/README.md

@@ -77,6 +77,7 @@ Here is a quick overview of the examples available in the RIOT:
 |---------|-------------|
 | [skald_eddystone](./skald_eddystone/README.md) | This example demonstrates the usage of `Skald` for creating an Google `Eddystone` beacon. |
 | [skald_ibeacon](./skald_ibeacon/README.md) | This example demonstrates the usage of `Skald` for creating an Apple `iBeacon`. |
+| [skald_bthome](./skald_bthome/README.md) | This example demonstrates the usage of `Skald` for sending SAUL measurements via [`BTHome`](https://bthome.io). |
 
 ### MQTT
 

examples/skald_bthome/Makefile

@@ -0,0 +1,24 @@
+# name of your application
+APPLICATION = skald_bthome
+
+# If no BOARD is found in the environment, use this default:
+BOARD ?= nrf52dk
+
+# This has to be the absolute path to the RIOT base directory:
+RIOTBASE ?= $(CURDIR)/../..
+
+# include Skald
+USEMODULE += skald_bthome
+
+DEVELHELP ?= 1
+
+BTHOME_NAME = "RIOT"
+BTHOME_ADV_INTERVAL ?= 60000
+
+CFLAGS += -DBTHOME_NAME="\"$(BTHOME_NAME)\""
+CFLAGS += -DBTHOME_ADV_INTERVAL=$(BTHOME_ADV_INTERVAL)
+
+# Change this to 0 show compiler invocation lines by default:
+QUIET ?= 1
+
+include $(RIOTBASE)/Makefile.include

examples/skald_bthome/README.md

@@ -0,0 +1,7 @@
+# Skald BTHome Example
+
+This example demonstrates the usage of `Skald` for creating a BTHome
+setup, advertising sensors in the SAUL registry.
+
+Simply compile and flash, and verify your newly created beacon with any type of
+BLE scanner / BTHome receiver (e.g. Home Assistant).

examples/skald_bthome/main.c

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2024 Martine S. Lenders
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     examples
+ * @{
+ *
+ * @file
+ * @brief       BLE BTHome example using Skald
+ *
+ * @author      Martine S. Lenders <mail@martine-lenders.eu>
+ *
+ * @}
+ */
+
+#include <stdio.h>
+
+#include "ztimer.h"
+
+#include "net/skald/bthome.h"
+
+#ifndef CONFIG_BTHOME_SAUL_REG_DEVS
+#define CONFIG_BTHOME_SAUL_REG_DEVS     (16U)
+#endif
+
+#ifndef BTHOME_ADV_INTERVAL
+#define BTHOME_ADV_INTERVAL             (60000U)
+#endif
+
+static skald_bthome_ctx_t _ctx;
+
+int main(void)
+{
+    ztimer_sleep(ZTIMER_MSEC, 2000);
+    printf("Skald and the tale of Harald's home\n");
+
+    if (skald_bthome_init(&_ctx, NULL, BTHOME_NAME, 0) < 0) {
+        return 1;
+    }
+    if (skald_bthome_add_uint24_measurement(&_ctx, BTHOME_ID_TEMPERATURE_FACTOR_0_01, 2500) < 0) {
+        return 1;
+    }
+    if (skald_bthome_add_int16_measurement(&_ctx, BTHOME_ID_HUMIDITY_FACTOR_0_01, 5055) < 0) {
+        printf("H %u\n", _ctx.skald.pkt.len);
+        return 1;
+    }
+    skald_bthome_advertise(&_ctx, BTHOME_ADV_INTERVAL);
+    return 0;
+}

sys/include/net/skald/bthome/defs.h

@@ -72,7 +72,7 @@ typedef enum {
      * 0 = Closed, 1 = Open
      */
     BTHOME_ID_OPENING_BINARY = 0x11,
-    BTHOME_ID_C02 = 0x12,                       /**< CO2 in _v_ ppm (uint16_t) */
+    BTHOME_ID_CO2 = 0x12,                       /**< CO2 in _v_ ppm (uint16_t) */
     BTHOME_ID_TVOC = 0x13,                      /**< TVOC in _v_ ug/m3 (uint16_t) */
     BTHOME_ID_MOISTURE_FACTOR_0_01 = 0x14,      /**< Moisture in _v_ * 0.01 % (uint16_t) */
     /**