BTHome: New feature

drivers/isl29020/isl29020_saul.c

@@ -28,7 +28,7 @@ static int read(const void *dev, phydat_t *res)
     res->val[0] = (int16_t)isl29020_read((const isl29020_t *)dev);
     res->val[1] = 0;
     res->val[2] = 0;
-    res->unit = UNIT_CD;
+    res->unit = UNIT_LUX;   /* https://www.renesas.com/en/document/dst/isl29020-datasheet */
     res->scale = 0;
     return 1;
 }

examples/skald_bthome/Makefile

@@ -0,0 +1,33 @@
+# 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 ?= $(CURDIR)/../..
+
+# include Skald using SAUL
+USEMODULE += saul_default
+USEMODULE += skald_bthome_saul
+
+DEVELHELP ?= 1
+
+BTHOME_NAME = "RIOT"
+BTHOME_ADV_INTERVAL ?= 60000
+ENCRYPTION_KEY ?=
+
+ifneq ($(ENCRYPTION_KEY),)
+  USEMODULE += skald_bthome_encrypt
+  CFLAGS += -DENCRYPTION_KEY="\"$(ENCRYPTION_KEY)\""
+endif
+
+CFLAGS += -DISR_STACKSIZE=1024
+
+CFLAGS += -DBTHOME_NAME="\"$(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 +1,149 @@
+/*
+ * 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 <[email protected]>
+ *
+ * @}
+ */
+
+#include <errno.h>
+#include <stdio.h>
+
+#include "saul_reg.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;
+static skald_bthome_saul_t _saul_devs[CONFIG_BTHOME_SAUL_REG_DEVS];
+
+#ifdef ENCRYPTION_KEY
+int _get_encryption_key(void)
+{
+    static const char enc_str[] = ENCRYPTION_KEY;
+    static uint8_t encryption_key[SKALD_BTHOME_KEY_LEN] = { 0 };
+    size_t enc_str_len = strlen(enc_str);
+    uint8_t key_len = 0;
+
+    uint8_t shift = 4;
+    for (unsigned i = 0; i < enc_str_len; i++) {
+        char c = enc_str[i];
+        unsigned char offset;
+
+        if (c >= '0' && c <= '9') {
+            offset = '0';
+        }
+        else if (c >= 'a' && c <= 'f') {
+            offset = 'a' - 10;
+        }
+        else {
+            continue;
+        }
+        encryption_key[i / 2] |= (c - offset) << shift;
+        shift = (shift) ? 0 : 4;
+        key_len = (i / 2) + 1;
+        if (key_len > SKALD_BTHOME_KEY_LEN) {
+            printf("Key was too long: %u bytes\n", key_len);
+            return -ENOBUFS;
+        }
+    }
+
+    if (key_len < SKALD_BTHOME_KEY_LEN) {
+            printf("Key was too short: %u bytes\n", key_len);
+        return -EINVAL;
+    }
+    memcpy(_ctx.key, encryption_key, key_len);
+    _ctx.encrypt = 1;
+    return key_len;
+}
+#endif
+
+static int _add_text(skald_bthome_ctx_t *ctx, uint8_t obj_id, phydat_t *data, uint8_t idx)
+{
+    static const char info[] = "RIOT";
+
+    (void)data;
+    (void)idx;
+    return skald_bthome_add_measurement(ctx, obj_id, info, strlen(info));
+}
+
+int main(void)
+{
+    saul_reg_t *dev = saul_reg;
+    unsigned i = 0;
+    int res;
+
+    ztimer_sleep(ZTIMER_MSEC, 2000);
+    printf("Skald and the tale of Harald's home\n");
+
+#ifdef ENCRYPTION_KEY
+    int key_len;
+
+    key_len = _get_encryption_key();
+
+    if (key_len != SKALD_BTHOME_KEY_LEN) {
+        printf(
+            "Key should be of length 16 (32 chars), "
+            "was \"%s\" (%u chars)\n",
+            ENCRYPTION_KEY,
+            strlen(ENCRYPTION_KEY)
+        );
+        return 1;
+    }
+#endif
+    _ctx.skald.update_pkt = NULL;
+    _ctx.devs = NULL;
+    if (skald_bthome_init(&_ctx, NULL, BTHOME_NAME, 0) < 0) {
+        return 1;
+    }
+    if (!saul_reg) {
+        puts("Hark! The board does not know SAUL. :-(");
+        return 1;
+    }
+    while (dev && (i < CONFIG_BTHOME_SAUL_REG_DEVS)) {
+        printf("Adding %s to BTHome.\n", dev->name);
+        _saul_devs[i].saul = *dev;  /* copy registry entry */
+        _saul_devs[i].saul.next = NULL;
+        if ((res = skald_bthome_saul_add(&_ctx, &_saul_devs[i])) < 0) {
+            errno = -res;
+            perror("Unable to add sensor to BTHome");
+        };
+        dev = dev->next;
+        i++;
+    }
+    assert(!saul_reg || _ctx.devs);
+    if (i < CONFIG_BTHOME_SAUL_REG_DEVS) {
+        memset(&_saul_devs[i].saul, 0, sizeof(_saul_devs[i].saul));
+        _saul_devs[i].obj_id = BTHOME_ID_TEXT;
+        _saul_devs[i].flags = SKALD_BTHOME_SAUL_FLAGS_CUSTOM;
+        _saul_devs[i].add_measurement = _add_text;
+        if ((res = skald_bthome_saul_add(&_ctx, &_saul_devs[i])) < 0) {
+            errno = -res;
+            perror("Unable to add text info to BTHome");
+        };
+        i++;
+    }
+    skald_bthome_advertise(&_ctx, BTHOME_ADV_INTERVAL);
+    printf("First advertisement should show up in %u ms\n", BTHOME_ADV_INTERVAL);
+    return 0;
+}

makefiles/pseudomodules.inc.mk

@@ -590,8 +590,12 @@ NO_PSEUDOMODULES += periph_common
 PSEUDOMODULES += pio_autostart_%
 
 # Submodules provided by Skald
+PSEUDOMODULES += skald_update_pkt_cb
 PSEUDOMODULES += skald_ibeacon
 PSEUDOMODULES += skald_eddystone
+PSEUDOMODULES += skald_bthome
+PSEUDOMODULES += skald_bthome_encrypt
+PSEUDOMODULES += skald_bthome_saul
 
 PSEUDOMODULES += crypto_aes_128
 PSEUDOMODULES += crypto_aes_192

sys/Makefile.dep

@@ -581,6 +581,17 @@ ifneq (,$(filter skald,$(USEMODULE)))
   USEMODULE += ztimer_msec
 endif
 
+ifneq (,$(filter skald_bthome_encrypt,$(USEMODULE)))
+  USEMODULE += cipher_modes
+  USEMODULE += skald_bthome
+endif
+
+ifneq (,$(filter skald_bthome_saul,$(USEMODULE)))
+  USEMODULE += skald_bthome
+  USEMODULE += skald_update_pkt_cb
+  USEMODULE += saul_reg
+endif
+
 ifneq (,$(filter bluetil_addr,$(USEMODULE)))
   USEMODULE += fmt
 endif

sys/include/net/skald.h

@@ -46,6 +46,7 @@
 
 #include <stdint.h>
 
+#include "kernel_defines.h"
 #include "ztimer.h"
 #include "net/ble.h"
 #include "net/netdev/ble.h"
@@ -68,16 +69,30 @@
     uint8_t u8[16];         /**< UUID with byte-wise access */
 } skald_uuid_t;
 
+
+/**
+ * @brief   Forward declaration
+ */
+typedef struct skald_ctx skald_ctx_t;
+
 /**
  * @brief   Advertising context holding the advertising data and state
  */
-typedef struct {
-    netdev_ble_pkt_t pkt;   /**< packet holding the advertisement (GAP) data */
-    ztimer_t timer;         /**< timer for scheduling advertising events */
-    ztimer_now_t last;      /**< last timer trigger (for offset compensation) */
-    uint8_t cur_chan;       /**< keep track of advertising channels */
-    uint32_t adv_itvl_ms;   /**< advertising interval [ms] */
-} skald_ctx_t;
+struct skald_ctx {
+    netdev_ble_pkt_t pkt;               /**< packet holding the advertisement (GAP) data */
+#if IS_USED(MODULE_SKALD_UPDATE_PKT_CB) || defined(DOXYGEN)
+    /**
+     * @brief callback to update packet on periodic advertisements
+     *
+     * Requires module `skald_pkt_update_cb`
+     */
+    void (*update_pkt)(skald_ctx_t *);
+#endif
+    ztimer_t timer;                     /**< timer for scheduling advertising events */
+    ztimer_now_t last;                  /**< last timer trigger (for offset compensation) */
+    uint8_t cur_chan;                   /**< keep track of advertising channels */
+    uint32_t adv_itvl_ms;               /**< advertising interval [ms] */
+};
 
 /**
  * @brief   Initialize Skald and the underlying radio