samples: bluetooth: HID SCI support in peripheral HID samples

This commit support for the HID
SCI characteristics in the peripheral_hids_mouse
and peripheral_hids_keyboard samples.

Signed-off-by: Artur Hadasz <artur.hadasz@nordicsemi.no>

Author: ahasztag

samples/bluetooth/peripheral_hids_keyboard/README.rst

@@ -125,6 +125,14 @@ User interface
       LED 3:
          Indicates if an NFC field is present.
 
+HID Shorter Connection Intervals (SCI)
+--------------------------------------
+
+If the sample is built with ``-DFILE_SUFFIX=hid_sci``, support for HID Shorter Connection Intervals (SCI) is enabled.
+This feature allows the device to enter a specific HID SCI mode when requested by the central.
+The HID SCI modes are sets of connection parameters which can be used to optimize the connection for the specific use case.
+For example, the FAST mode is used to achieve the shortest connection intervals, allowing for minimum latency and maximum throughput.
+
 Configuration
 *************
 
@@ -154,6 +162,8 @@ Building and running
 
 .. include:: /includes/ipc_radio_conf.txt
 
+To build the sample with HID SCI support, build with ``-DFILE_SUFFIX=hid_sci``
+
 Testing
 =======
 

samples/bluetooth/peripheral_hids_keyboard/boards/nrf5340dk_nrf5340_cpuapp_hid_sci.conf

@@ -0,0 +1,12 @@
+#
+# Copyright (c) 2026 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+# The radio notification connection callbacks are not available
+# from the nRF5340 application core.
+CONFIG_BT_RADIO_NOTIFICATION_CONN_CB=n
+
+# 1000 us minimum connection interval - local controller minimum for nRF5340
+CONFIG_BT_HIDS_SCI_FAST_INTERVAL_MIN_125US=8

samples/bluetooth/peripheral_hids_keyboard/boards/nrf5340dk_nrf5340_cpuapp_ns_hid_sci.conf

@@ -0,0 +1,17 @@
+#
+# Copyright (c) 2026 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+# TF-M profile has to be properly configured to be able to run
+# the Bluetooth stack which uses PSA crypto API as minimal TF-M
+# profile cannot be used.
+CONFIG_TFM_PROFILE_TYPE_SMALL=y
+
+# The radio notification connection callbacks are not available
+# from the nRF5340 application core.
+CONFIG_BT_RADIO_NOTIFICATION_CONN_CB=n
+
+# 1000 us minimum connection interval - local controller minimum for nRF5340
+CONFIG_BT_HIDS_SCI_FAST_INTERVAL_MIN_125US=8

samples/bluetooth/peripheral_hids_keyboard/prj_hid_sci.conf

@@ -0,0 +1,78 @@
+#
+# Copyright (c) 2026 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+CONFIG_NCS_SAMPLES_DEFAULTS=y
+
+CONFIG_BT=y
+CONFIG_BT_MAX_CONN=1
+CONFIG_BT_MAX_PAIRED=1
+CONFIG_BT_SMP=y
+CONFIG_BT_ATT_TX_COUNT=5
+CONFIG_BT_PERIPHERAL=y
+CONFIG_BT_DEVICE_NAME="Nordic_HIDS_keyboard"
+CONFIG_BT_DEVICE_APPEARANCE=961
+
+# Disable automatic initiation of PHY updates and the SMP Security Requests.
+# Workaround to prevent disconnection with the following disconnect reasons:
+# - 0x08 (BT_HCI_ERR_CONN_TIMEOUT)
+# - 0x13 (BT_HCI_ERR_REMOTE_USER_TERM_CONN)
+# - 0x23 (BT_HCI_ERR_LL_PROC_COLLISION)
+# - 0x2A (BT_HCI_ERR_DIFF_TRANS_COLLISION)
+# Some laptop Bluetooth controllers may simultaneously trigger two Link Layer
+# procedures which results in a procedure collision and disconnection.
+CONFIG_BT_GATT_AUTO_SEC_REQ=n
+CONFIG_BT_AUTO_PHY_UPDATE=n
+
+CONFIG_BT_BAS=y
+CONFIG_BT_HIDS=y
+CONFIG_BT_HIDS_INPUT_REP_MAX=1
+CONFIG_BT_HIDS_OUTPUT_REP_MAX=1
+CONFIG_BT_HIDS_FEATURE_REP_MAX=0
+CONFIG_BT_HIDS_MAX_CLIENT_COUNT=1
+CONFIG_BT_HIDS_DEFAULT_PERM_RW_ENCRYPT=y
+CONFIG_BT_GATT_UUID16_POOL_SIZE=40
+CONFIG_BT_GATT_CHRC_POOL_SIZE=20
+
+CONFIG_BT_CONN_CTX=y
+
+CONFIG_BT_DIS=y
+CONFIG_BT_DIS_MANUF_NAME=y
+CONFIG_BT_DIS_MANUF_NAME_STR="NordicSemiconductor"
+CONFIG_BT_DIS_PNP=y
+CONFIG_BT_DIS_PNP_VID_SRC=2
+CONFIG_BT_DIS_PNP_VID=0x1915
+CONFIG_BT_DIS_PNP_PID=0xEEEF
+CONFIG_BT_DIS_PNP_VER=0x0100
+
+CONFIG_MAIN_STACK_SIZE=2048
+CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048
+
+CONFIG_BT_SETTINGS=y
+CONFIG_FLASH=y
+CONFIG_FLASH_PAGE_LAYOUT=y
+CONFIG_FLASH_MAP=y
+
+CONFIG_DK_LIBRARY=y
+
+# HID SCI configuration
+CONFIG_BT_HIDS_ATTR_MAX=30
+
+CONFIG_BT_GAP_PERIPHERAL_PREF_PARAMS=n
+
+CONFIG_BT_SUBRATING=y
+CONFIG_BT_LE_EXTENDED_FEAT_SET=y
+
+CONFIG_BT_SHORTER_CONNECTION_INTERVALS=y
+
+CONFIG_BT_HIDS_SCI=y
+
+# Optimize for best possible performance in HID SCI FAST mode
+
+# 875 us minimum connection interval
+CONFIG_BT_HIDS_SCI_FAST_INTERVAL_MIN_125US=7
+
+# Keep the maximum connection event below the minimum connection interval of 875 us
+# Without this, the effective minimum connection interval would be 1125 us.
+CONFIG_BT_CTLR_SDC_MAX_CONN_EVENT_LEN_DEFAULT=750

samples/bluetooth/peripheral_hids_keyboard/sample.yaml

@@ -39,3 +39,16 @@ tests:
         - "Starting Bluetooth Peripheral HIDS keyboard sample"
         - "Bluetooth initialized"
     timeout: 15
+  sample.bluetooth.peripheral_hids_keyboard.hid_sci:
+    harness: console
+    extra_args: FILE_SUFFIX=hid_sci
+    integration_platforms:
+      - nrf54l15dk/nrf54l05/cpuapp
+      - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
+      - nrf54lv10dk/nrf54lv10a/cpuapp
+    platform_allow:
+      - nrf54l15dk/nrf54l05/cpuapp
+      - nrf54lm20dk/nrf54lm20a/cpuapp
+      - nrf54lm20dk/nrf54lm20b/cpuapp
+      - nrf54lv10dk/nrf54lv10a/cpuapp

samples/bluetooth/peripheral_hids_keyboard/src/main.c

@@ -131,6 +131,7 @@ static const struct bt_data sd[] = {
 static struct conn_mode {
 	struct bt_conn *conn;
 	bool in_boot_mode;
+	enum bt_hids_sci_mode_value requested_sci_mode;
 } conn_mode[CONFIG_BT_HIDS_MAX_CLIENT_COUNT];
 
 static const uint8_t hello_world_str[] = {
@@ -269,6 +270,9 @@ static void connected(struct bt_conn *conn, uint8_t err)
 		if (!conn_mode[i].conn) {
 			conn_mode[i].conn = conn;
 			conn_mode[i].in_boot_mode = false;
+			if (IS_ENABLED(CONFIG_BT_HIDS_SCI)) {
+				conn_mode[i].requested_sci_mode = BT_HIDS_SCI_MODE_NONE;
+			}
 			break;
 		}
 	}
@@ -342,10 +346,95 @@ static void security_changed(struct bt_conn *conn, bt_security_t level,
 	}
 }
 
+#ifdef CONFIG_BT_HIDS_SCI
+static const char *sci_mode_to_string(enum bt_hids_sci_mode_value mode)
+{
+	switch (mode) {
+	case BT_HIDS_SCI_MODE_NONE:
+		return "NONE";
+	case BT_HIDS_SCI_MODE_DEFAULT:
+		return "DEFAULT";
+	case BT_HIDS_SCI_MODE_FAST:
+		return "FAST";
+	case BT_HIDS_SCI_MODE_LOW_POWER:
+		return "LOW_POWER";
+	case BT_HIDS_SCI_MODE_FULL_RANGE:
+		return "FULL_RANGE";
+	}
+
+	return "UNKNOWN";
+}
+
+static void conn_rate_changed(struct bt_conn *conn, uint8_t status,
+			      const struct bt_conn_le_conn_rate_changed *params)
+{
+	size_t i;
+	enum bt_hids_sci_mode_value requested_sci_mode;
+	bool mode_changed = false;
+
+	for (i = 0; i < ARRAY_SIZE(conn_mode); i++) {
+		if (conn_mode[i].conn == conn) {
+			break;
+		}
+	}
+
+	if (i >= ARRAY_SIZE(conn_mode)) {
+		return;
+	}
+
+	printk(
+		"\nConnection rate changed:\n"
+		" interval us: %d\n"
+		" subrate factor: %d\n"
+		" peripheral latency: %d\n"
+		" continuation number: %d\n"
+		" supervision timeout (10ms units): %d\n",
+		params->interval_us,
+		params->subrate_factor,
+		params->peripheral_latency,
+		params->continuation_number,
+		params->supervision_timeout_10ms
+	);
+
+	requested_sci_mode = conn_mode[i].requested_sci_mode;
+	conn_mode[i].requested_sci_mode = BT_HIDS_SCI_MODE_NONE;
+
+	/* In case a connection rate change is received without a prior HID SCI mode change request,
+	 * or if a HID SCI mode change was requested but the new connection rate parameters
+	 * are not valid for the requested mode,
+	 * this sample simply ignores the event and does not update the HID SCI mode.
+	 * In a real application a different approach might be chosen, e.g. cycling through the
+	 * available SCI modes to determine which mode the new parameters are compatible with,
+	 * or default to the FULL_RANGE mode.
+	 */
+	if (requested_sci_mode == BT_HIDS_SCI_MODE_NONE) {
+		printk("No pending HID SCI mode change request\n");
+	} else if (bt_hids_sci_mode_validate(requested_sci_mode, params)) {
+		int err = bt_hids_sci_mode_updated(conn, requested_sci_mode);
+
+		if (!err) {
+			mode_changed = true;
+		} else {
+			printk("Failed to update SCI mode: %d\n", err);
+		}
+	} else {
+		printk("Invalid SCI mode parameters for mode %d\n", requested_sci_mode);
+	}
+
+	if (mode_changed) {
+		printk("SCI mode updated to: %s for connection %zu\n",
+		       sci_mode_to_string(requested_sci_mode), i);
+	}
+}
+#endif
+
 BT_CONN_CB_DEFINE(conn_callbacks) = {
 	.connected = connected,
 	.disconnected = disconnected,
 	.security_changed = security_changed,
+#ifdef CONFIG_BT_HIDS_SCI
+	.conn_rate_changed = conn_rate_changed,
+#endif /* CONFIG_BT_HIDS_SCI */
 };
 
 
@@ -426,6 +515,62 @@ static void hids_pm_evt_handler(enum bt_hids_pm_evt evt,
 	}
 }
 
+static void conn_cp_evt_handler(enum bt_hids_cp_evt evt, struct bt_conn *conn)
+{
+	const char *evt_str = "UNKNOWN";
+	enum bt_hids_sci_mode_value new_mode = BT_HIDS_SCI_MODE_NONE;
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(conn_mode); i++) {
+		if (conn_mode[i].conn == conn) {
+			break;
+		}
+	}
+
+	if (i >= ARRAY_SIZE(conn_mode)) {
+		return;
+	}
+
+	switch (evt) {
+	case BT_HIDS_CP_EVT_HOST_SUSP:
+		evt_str = "SUSP";
+		break;
+	case BT_HIDS_CP_EVT_HOST_EXIT_SUSP:
+		evt_str = "EXIT_SUSP";
+		break;
+	case BT_HIDS_CP_EVT_HOST_SCI_DEFAULT_REQ:
+		evt_str = "SCI_DEFAULT_REQ";
+		new_mode = BT_HIDS_SCI_MODE_DEFAULT;
+		break;
+	case BT_HIDS_CP_EVT_HOST_SCI_FAST_REQ:
+		evt_str = "SCI_FAST_REQ";
+		new_mode = BT_HIDS_SCI_MODE_FAST;
+		break;
+	case BT_HIDS_CP_EVT_HOST_SCI_LOW_POWER_REQ:
+		evt_str = "SCI_LOW_POWER_REQ";
+		new_mode = BT_HIDS_SCI_MODE_LOW_POWER;
+		break;
+	case BT_HIDS_CP_EVT_HOST_SCI_FULL_RANGE_REQ:
+		evt_str = "SCI_FULL_RANGE_REQ";
+		new_mode = BT_HIDS_SCI_MODE_FULL_RANGE;
+		break;
+	default:
+		evt_str = "UNKNOWN";
+		break;
+	}
+
+	printk("Control point event received for connection %u: %s\n", i, evt_str);
+
+	if (new_mode != BT_HIDS_SCI_MODE_NONE) {
+		int err = bt_hids_sci_mode_change_request(conn, new_mode);
+
+		if (!err) {
+			conn_mode[i].requested_sci_mode = new_mode;
+		} else {
+			printk("Failed to request SCI mode change: %d\n", err);
+		}
+	}
+}
 
 static void hid_init(void)
 {
@@ -508,6 +653,9 @@ static void hid_init(void)
 	hids_init_obj.is_kb = true;
 	hids_init_obj.boot_kb_outp_rep_handler = hids_boot_kb_outp_rep_handler;
 	hids_init_obj.pm_evt_handler = hids_pm_evt_handler;
+	if (IS_ENABLED(CONFIG_BT_HIDS_SCI)) {
+		hids_init_obj.conn_cp_evt_handler = conn_cp_evt_handler;
+	}
 
 	err = bt_hids_init(&hids_obj, &hids_init_obj);
 	__ASSERT(err == 0, "HIDS initialization failed\n");

samples/bluetooth/peripheral_hids_keyboard/sysbuild/ipc_radio/prj_hid_sci.conf

@@ -0,0 +1,35 @@
+#
+# Copyright (c) 2026 Nordic Semiconductor
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+CONFIG_HEAP_MEM_POOL_SIZE=8192
+CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048
+
+CONFIG_MBOX=y
+CONFIG_IPC_SERVICE=y
+
+CONFIG_BT=y
+CONFIG_BT_HCI_RAW=y
+#CONFIG_BT_MAX_CONN=16
+
+# 254 is the minimum CONFIG_BT_BUF_EVT_RX_SIZE to support bt_conn_le_read_min_conn_interval_groups.
+# This function is used by in order to load HID SCI information.
+CONFIG_BT_BUF_EVT_RX_SIZE=254
+
+CONFIG_BT_MAX_CONN=1
+CONFIG_BT_CENTRAL=n
+
+CONFIG_IPC_RADIO_BT=y
+CONFIG_IPC_RADIO_BT_HCI_IPC=y
+
+CONFIG_BT_CTLR_EXTENDED_FEAT_SET=y
+CONFIG_BT_CTLR_SUBRATING=y
+CONFIG_BT_CTLR_SHORTER_CONNECTION_INTERVALS=y
+
+# Optimize for best possible performance in HID SCI FAST mode
+
+# Keep the maximum connection event below the minimum connection interval of 875 us
+# Without this, the effective minimum connection interval is 1125 us.
+CONFIG_BT_CTLR_SDC_MAX_CONN_EVENT_LEN_DEFAULT=750

samples/bluetooth/peripheral_hids_mouse/README.rst

@@ -147,6 +147,14 @@ The high-duty cycle directed advertising has a timeout of 1.28 seconds defined b
 If the timeout occurs, the device starts directed advertising to the next bonded peer.
 If all bonding information is used and there is still no connection, the regular advertising starts.
 
+HID Shorter Connection Intervals (SCI)
+--------------------------------------
+
+If the sample is built with ``-DFILE_SUFFIX=hid_sci``, support for HID Shorter Connection Intervals (SCI) is enabled.
+This feature allows the device to enter a specific HID SCI mode when requested by the central.
+The HID SCI modes are sets of connection parameters which can be used to optimize the connection for the specific use case.
+For example, the FAST mode is used to achieve the shortest connection intervals, allowing for minimum latency and maximum throughput.
+
 Building and running
 ********************
 
@@ -161,6 +169,8 @@ Building and running
 
 .. _peripheral_hids_mouse_bt_rpc_build:
 
+To build the sample with HID SCI support, build with ``-DFILE_SUFFIX=hid_sci``
+
 Bluetooth RPC build
 ===================