circuitpython/ports/nrf/common-hal/bleio/Device.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2018 Artur Pacholec
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include <string.h>
#include <stdio.h>

#include "ble.h"
#include "ble_drv.h"
#include "ble_hci.h"
#include "nrf_soc.h"
#include "py/objstr.h"
#include "py/runtime.h"
#include "shared-bindings/bleio/Adapter.h"
#include "shared-bindings/bleio/Characteristic.h"
#include "shared-bindings/bleio/Device.h"
#include "shared-bindings/bleio/Service.h"
#include "shared-bindings/bleio/UUID.h"

#define BLE_MIN_CONN_INTERVAL        MSEC_TO_UNITS(15, UNIT_0_625_MS)
#define BLE_MAX_CONN_INTERVAL        MSEC_TO_UNITS(300, UNIT_0_625_MS)
#define BLE_SLAVE_LATENCY            0
#define BLE_CONN_SUP_TIMEOUT         MSEC_TO_UNITS(4000, UNIT_10_MS)

#define BLE_ADV_LENGTH_FIELD_SIZE   1
#define BLE_ADV_AD_TYPE_FIELD_SIZE  1
#define BLE_AD_TYPE_FLAGS_DATA_SIZE 1

#ifndef BLE_GAP_ADV_MAX_SIZE
#define BLE_GAP_ADV_MAX_SIZE         31
#endif

static bleio_service_obj_t *m_char_discovery_service;
static volatile bool m_discovery_successful;
static nrf_mutex_t *m_discovery_mutex;

#if (BLUETOOTH_SD == 140)
static uint8_t m_adv_handle = BLE_GAP_ADV_SET_HANDLE_NOT_SET;

static uint8_t m_scan_buffer_data[BLE_GAP_SCAN_BUFFER_MIN];

static ble_data_t m_scan_buffer = {
    .p_data = m_scan_buffer_data,
    .len = BLE_GAP_SCAN_BUFFER_MIN
};
#endif

STATIC uint32_t set_advertisement_data(bleio_device_obj_t *device, bool connectable, mp_buffer_info_t *raw_data) {
    common_hal_bleio_adapter_set_enabled(true);

    uint8_t adv_data[BLE_GAP_ADV_MAX_SIZE];
    uint8_t byte_pos = 0;
    uint32_t err_code;

#define ADD_FIELD(field, len) \
    do { \
        if (byte_pos + (len) > BLE_GAP_ADV_MAX_SIZE) { \
            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError, \
                "Can not fit data into the advertisment packet")); \
        } \
        adv_data[byte_pos] = (field); \
        byte_pos += (len); \
    } while (0)

    GET_STR_DATA_LEN(device->name, name_data, name_len);
    if (name_len > 0) {
        ble_gap_conn_sec_mode_t sec_mode;
        BLE_GAP_CONN_SEC_MODE_SET_OPEN(&sec_mode);

        err_code = sd_ble_gap_device_name_set(&sec_mode, name_data, name_len);
        if (err_code != NRF_SUCCESS) {
            return err_code;
        }

        // TODO: Shorten if too long

        ADD_FIELD(BLE_ADV_AD_TYPE_FIELD_SIZE + name_len, BLE_ADV_LENGTH_FIELD_SIZE);
        ADD_FIELD(BLE_GAP_AD_TYPE_COMPLETE_LOCAL_NAME, BLE_ADV_AD_TYPE_FIELD_SIZE);

        memcpy(&adv_data[byte_pos], name_data, name_len);
        byte_pos += name_len;
    }

    // set flags, default to disc mode
    if (raw_data->len == 0) {
        ADD_FIELD(BLE_ADV_AD_TYPE_FIELD_SIZE + BLE_AD_TYPE_FLAGS_DATA_SIZE, BLE_ADV_LENGTH_FIELD_SIZE);
        ADD_FIELD(BLE_GAP_AD_TYPE_FLAGS, BLE_AD_TYPE_FLAGS_DATA_SIZE);
        ADD_FIELD(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE, BLE_AD_TYPE_FLAGS_DATA_SIZE);
    } else  {
        if (byte_pos + raw_data->len > BLE_GAP_ADV_MAX_SIZE) {
            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                "Can not fit data into the advertisment packet"));
        }

        memcpy(&adv_data[byte_pos], raw_data->buf, raw_data->len);
        byte_pos += raw_data->len;
    }

    const mp_obj_list_t *service_list = MP_OBJ_TO_PTR(device->service_list);
    if (service_list->len > 0) {
        bool has_128bit_services = false;
        bool has_16bit_services = false;

        for (size_t i = 0; i < service_list->len; ++i) {
            const bleio_service_obj_t *service = MP_OBJ_TO_PTR(service_list->items[i]);

            if (service->is_secondary) {
                continue;
            }

            if (service->uuid->type == UUID_TYPE_16BIT) {
                has_16bit_services = true;
            }

            if (service->uuid->type == UUID_TYPE_128BIT) {
                has_128bit_services = true;
            }
        }

        if (has_16bit_services) {
            const uint8_t size_byte_pos = byte_pos;
            uint8_t uuid_total_size = 0;

            // skip length byte for now, apply total length post calculation
            byte_pos += BLE_ADV_LENGTH_FIELD_SIZE;

            ADD_FIELD(BLE_GAP_AD_TYPE_16BIT_SERVICE_UUID_COMPLETE, BLE_ADV_AD_TYPE_FIELD_SIZE);

            for (size_t i = 0; i < service_list->len; ++i) {
                const bleio_service_obj_t *service = MP_OBJ_TO_PTR(service_list->items[i]);
                uint8_t encoded_size = 0;

                if ((service->uuid->type != UUID_TYPE_16BIT) || service->is_secondary) {
                    continue;
                }

                ble_uuid_t uuid;
                uuid.type = BLE_UUID_TYPE_BLE;
                uuid.uuid = service->uuid->value[0] | (service->uuid->value[1] << 8);

                err_code = sd_ble_uuid_encode(&uuid, &encoded_size, &adv_data[byte_pos]);
                if (err_code != NRF_SUCCESS) {
                    return err_code;
                }

                uuid_total_size += encoded_size;
                byte_pos += encoded_size;
            }

            adv_data[size_byte_pos] = (BLE_ADV_AD_TYPE_FIELD_SIZE + uuid_total_size);
        }

        if (has_128bit_services) {
            const uint8_t size_byte_pos = byte_pos;
            uint8_t uuid_total_size = 0;

            // skip length byte for now, apply total length post calculation
            byte_pos += BLE_ADV_LENGTH_FIELD_SIZE;

            ADD_FIELD(BLE_GAP_AD_TYPE_128BIT_SERVICE_UUID_COMPLETE, BLE_ADV_AD_TYPE_FIELD_SIZE);

            for (size_t i = 0; i < service_list->len; ++i) {
                const bleio_service_obj_t *service = MP_OBJ_TO_PTR(service_list->items[i]);
                uint8_t encoded_size = 0;

                if ((service->uuid->type != UUID_TYPE_128BIT) || service->is_secondary) {
                    continue;
                }

                ble_uuid_t uuid;
                uuid.type = service->uuid->uuid_vs_idx;
                uuid.uuid = service->uuid->value[0] | (service->uuid->value[1] << 8);

                err_code = sd_ble_uuid_encode(&uuid, &encoded_size, &adv_data[byte_pos]);
                if (err_code != NRF_SUCCESS) {
                    return err_code;
                }

                uuid_total_size += encoded_size;
                byte_pos += encoded_size;
            }

            adv_data[size_byte_pos] = (BLE_ADV_AD_TYPE_FIELD_SIZE + uuid_total_size);
        }
    }

#if (BLUETOOTH_SD == 132)
    err_code = sd_ble_gap_adv_data_set(adv_data, byte_pos, NULL, 0);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }
#endif

    static ble_gap_adv_params_t m_adv_params = {
        .interval = MSEC_TO_UNITS(100, UNIT_0_625_MS),
#if (BLUETOOTH_SD == 140)
        .properties.type = BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED,
        .duration = BLE_GAP_ADV_TIMEOUT_GENERAL_UNLIMITED,
        .filter_policy = BLE_GAP_ADV_FP_ANY,
        .primary_phy = BLE_GAP_PHY_1MBPS,
#else
        .type = BLE_GAP_ADV_TYPE_ADV_IND,
        .fp = BLE_GAP_ADV_FP_ANY,
#endif
    };

    if (!connectable) {
#if (BLUETOOTH_SD == 140)
        m_adv_params.properties.type = BLE_GAP_ADV_TYPE_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED;
#else
        m_adv_params.type = BLE_GAP_ADV_TYPE_ADV_NONCONN_IND;
#endif
    }

    common_hal_bleio_device_stop_advertising(device);

#if (BLUETOOTH_SD == 140)
    const ble_gap_adv_data_t ble_gap_adv_data = {
        .adv_data.p_data = adv_data,
        .adv_data.len = byte_pos,
    };

    err_code = sd_ble_gap_adv_set_configure(&m_adv_handle, &ble_gap_adv_data, &m_adv_params);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }

    err_code = sd_ble_gap_adv_start(m_adv_handle, BLE_CONN_CFG_TAG_CUSTOM);
#elif (BLUETOOTH_SD == 132 && BLE_API_VERSION == 4)
    err_code = sd_ble_gap_adv_start(&m_adv_params, BLE_CONN_CFG_TAG_CUSTOM);
#else
    err_code = sd_ble_gap_adv_start(&m_adv_params);
#endif

    return err_code;
}

STATIC bool discover_services(bleio_device_obj_t *device, uint16_t start_handle) {
    m_discovery_successful = false;

    uint32_t err_code = sd_ble_gattc_primary_services_discover(device->conn_handle, start_handle, NULL);
    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                  "Failed to discover serivices, status: 0x%08lX", err_code));
    }

    err_code = sd_mutex_acquire(m_discovery_mutex);
    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                  "Failed to acquire mutex, status: 0x%08lX", err_code));
    }

    while (sd_mutex_acquire(m_discovery_mutex) == NRF_ERROR_SOC_MUTEX_ALREADY_TAKEN) {
#ifdef MICROPY_VM_HOOK_LOOP
    MICROPY_VM_HOOK_LOOP
#endif
    }

    err_code = sd_mutex_release(m_discovery_mutex);
    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                  "Failed to release mutex, status: 0x%08lX", err_code));
    }

    return m_discovery_successful;
}

STATIC bool discover_characteristics(bleio_device_obj_t *device, bleio_service_obj_t *service, uint16_t start_handle) {
    m_char_discovery_service = service;

    ble_gattc_handle_range_t handle_range;
    handle_range.start_handle = start_handle;
    handle_range.end_handle = service->end_handle;

    m_discovery_successful = false;

    uint32_t err_code = sd_ble_gattc_characteristics_discover(device->conn_handle, &handle_range);
    if (err_code != 0) {
        return false;
    }

    err_code = sd_mutex_acquire(m_discovery_mutex);
    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                  "Failed to acquire mutex, status: 0x%08lX", err_code));
    }

    while (sd_mutex_acquire(m_discovery_mutex) == NRF_ERROR_SOC_MUTEX_ALREADY_TAKEN) {
#ifdef MICROPY_VM_HOOK_LOOP
    MICROPY_VM_HOOK_LOOP
#endif
    }

    err_code = sd_mutex_release(m_discovery_mutex);
    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                  "Failed to release mutex, status: 0x%08lX", err_code));
    }

    return m_discovery_successful;
}

STATIC void on_primary_srv_discovery_rsp(ble_gattc_evt_prim_srvc_disc_rsp_t *response, bleio_device_obj_t *device) {
    for (size_t i = 0; i < response->count; ++i) {
        const ble_gattc_service_t *gattc_service = &response->services[i];

        bleio_service_obj_t *service = m_new_obj(bleio_service_obj_t);
        service->base.type = &bleio_service_type;
        service->device = device;
        service->char_list = mp_obj_new_list(0, NULL);
        service->start_handle = gattc_service->handle_range.start_handle;
        service->end_handle = gattc_service->handle_range.end_handle;
        service->handle = gattc_service->handle_range.start_handle;

        bleio_uuid_obj_t *uuid = m_new_obj(bleio_uuid_obj_t);
        uuid->base.type = &bleio_uuid_type;
        uuid->type = (gattc_service->uuid.type == BLE_UUID_TYPE_BLE) ? UUID_TYPE_16BIT : UUID_TYPE_128BIT;
        uuid->value[0] = gattc_service->uuid.uuid & 0xFF;
        uuid->value[1] = gattc_service->uuid.uuid >> 8;
        service->uuid = uuid;

        mp_obj_list_append(device->service_list, service);
    }

    if (response->count > 0) {
        m_discovery_successful = true;
    }

    const uint32_t err_code = sd_mutex_release(m_discovery_mutex);
    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                  "Failed to release mutex, status: 0x%08lX", err_code));
    }
}

STATIC void on_char_discovery_rsp(ble_gattc_evt_char_disc_rsp_t *response, bleio_device_obj_t *device) {
    for (size_t i = 0; i < response->count; ++i) {
        const ble_gattc_char_t *gattc_char = &response->chars[i];

        bleio_characteristic_obj_t *characteristic = m_new_obj(bleio_characteristic_obj_t);
        characteristic->base.type = &bleio_characteristic_type;

        bleio_uuid_obj_t *uuid = m_new_obj(bleio_uuid_obj_t);
        uuid->base.type = &bleio_uuid_type;
        uuid->type = (gattc_char->uuid.type == BLE_UUID_TYPE_BLE) ? UUID_TYPE_16BIT : UUID_TYPE_128BIT;
        uuid->value[0] = gattc_char->uuid.uuid & 0xFF;
        uuid->value[1] = gattc_char->uuid.uuid >> 8;
        characteristic->uuid = uuid;

        characteristic->props.broadcast = gattc_char->char_props.broadcast;
        characteristic->props.indicate = gattc_char->char_props.indicate;
        characteristic->props.notify = gattc_char->char_props.notify;
        characteristic->props.read = gattc_char->char_props.read;
        characteristic->props.write = gattc_char->char_props.write;
        characteristic->props.write_wo_resp = gattc_char->char_props.write_wo_resp;
        characteristic->handle = gattc_char->handle_value;

        characteristic->service_handle = m_char_discovery_service->handle;
        characteristic->service = m_char_discovery_service;

        mp_obj_list_append(m_char_discovery_service->char_list, MP_OBJ_FROM_PTR(characteristic));
    }

    if (response->count > 0) {
        m_discovery_successful = true;
    }

    const uint32_t err_code = sd_mutex_release(m_discovery_mutex);
    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                  "Failed to release mutex, status: 0x%08lX", err_code));
    }
}

STATIC void on_adv_report(ble_gap_evt_adv_report_t *report, bleio_device_obj_t *device) {
    uint32_t err_code;

    if (memcmp(report->peer_addr.addr, device->address.value, BLEIO_ADDRESS_BYTES) != 0) {
#if (BLUETOOTH_SD == 140)
        err_code = sd_ble_gap_scan_start(NULL, &m_scan_buffer);
        if (err_code != NRF_SUCCESS) {
            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                "Failed to continue scanning, status: 0x%0xlX", err_code));
        }
#endif
        return;
    }

    ble_gap_scan_params_t scan_params = {
        .active = 1,
        .interval = MSEC_TO_UNITS(100, UNIT_0_625_MS),
        .window = MSEC_TO_UNITS(100, UNIT_0_625_MS),
    };

    ble_gap_addr_t addr;
    memset(&addr, 0, sizeof(addr));

    addr.addr_type = report->peer_addr.addr_type;
    memcpy(addr.addr, report->peer_addr.addr, BLEIO_ADDRESS_BYTES);

    ble_gap_conn_params_t conn_params = {
        .min_conn_interval = BLE_MIN_CONN_INTERVAL,
        .max_conn_interval = BLE_MAX_CONN_INTERVAL,
        .conn_sup_timeout = BLE_CONN_SUP_TIMEOUT,
        .slave_latency = BLE_SLAVE_LATENCY,
    };

#if (BLE_API_VERSION == 2)
    err_code = sd_ble_gap_connect(&addr, &scan_params, &conn_params);
#else
    err_code = sd_ble_gap_connect(&addr, &scan_params, &conn_params, BLE_CONN_CFG_TAG_CUSTOM);
#endif

    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
            "Failed to connect, status: 0x%08lX", err_code));
    }
}

STATIC void on_ble_evt(ble_evt_t *ble_evt, void *device_in) {
    bleio_device_obj_t *device = (bleio_device_obj_t*)device_in;

    switch (ble_evt->header.evt_id) {
        case BLE_GAP_EVT_CONNECTED:
        {
            ble_gap_conn_params_t conn_params;
            device->conn_handle = ble_evt->evt.gap_evt.conn_handle;

            sd_ble_gap_ppcp_get(&conn_params);
            sd_ble_gap_conn_param_update(ble_evt->evt.gap_evt.conn_handle, &conn_params);
            break;
        }

        case BLE_GAP_EVT_DISCONNECTED:
            device->conn_handle = BLE_CONN_HANDLE_INVALID;
            break;

        case BLE_GAP_EVT_ADV_REPORT:
            on_adv_report(&ble_evt->evt.gap_evt.params.adv_report, device);
            break;

        case BLE_GATTC_EVT_PRIM_SRVC_DISC_RSP:
            on_primary_srv_discovery_rsp(&ble_evt->evt.gattc_evt.params.prim_srvc_disc_rsp, device);
            break;

        case BLE_GATTC_EVT_CHAR_DISC_RSP:
            on_char_discovery_rsp(&ble_evt->evt.gattc_evt.params.char_disc_rsp, device);
            break;

        case BLE_GATTS_EVT_SYS_ATTR_MISSING:
            sd_ble_gatts_sys_attr_set(ble_evt->evt.gatts_evt.conn_handle, NULL, 0, 0);
            break;

#if (BLE_API_VERSION == 4)
        case BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST:
            sd_ble_gatts_exchange_mtu_reply(device->conn_handle, BLE_GATT_ATT_MTU_DEFAULT);
            break;
#endif

        case BLE_GAP_EVT_SEC_PARAMS_REQUEST:
            sd_ble_gap_sec_params_reply(device->conn_handle, BLE_GAP_SEC_STATUS_PAIRING_NOT_SUPP, NULL, NULL);
            break;

        case BLE_GAP_EVT_CONN_PARAM_UPDATE_REQUEST:
        {
            ble_gap_evt_conn_param_update_request_t *request = &ble_evt->evt.gap_evt.params.conn_param_update_request;
            sd_ble_gap_conn_param_update(device->conn_handle, &request->conn_params);
            break;
        }
    }
}

void common_hal_bleio_device_start_advertising(bleio_device_obj_t *device, bool connectable, mp_buffer_info_t *raw_data) {
    if (connectable) {
        ble_drv_add_event_handler(on_ble_evt, device);
    }

    const uint32_t err_code = set_advertisement_data(device, connectable, raw_data);
    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
            "Failed to start advertisment, status: 0x%08lX", err_code));
    }
}

void common_hal_bleio_device_stop_advertising(bleio_device_obj_t *device) {
    uint32_t err_code;

#if (BLUETOOTH_SD == 140)
    if (m_adv_handle == BLE_GAP_ADV_SET_HANDLE_NOT_SET)
        return;

    err_code = sd_ble_gap_adv_stop(m_adv_handle);
#else
    err_code = sd_ble_gap_adv_stop();
#endif

    if ((err_code != NRF_SUCCESS) && (err_code != NRF_ERROR_INVALID_STATE)) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
            "Failed to stop advertisment, status: 0x%08lX", err_code));
    }
}

void common_hal_bleio_device_connect(bleio_device_obj_t *device) {
    ble_drv_add_event_handler(on_ble_evt, device);

    ble_gap_scan_params_t scan_params = {
        .interval = MSEC_TO_UNITS(100, UNIT_0_625_MS),
        .window = MSEC_TO_UNITS(100, UNIT_0_625_MS),
#if (BLUETOOTH_SD == 140)
        .scan_phys = BLE_GAP_PHY_1MBPS,
#endif
    };

    common_hal_bleio_adapter_set_enabled(true);

    uint32_t err_code;
#if (BLUETOOTH_SD == 140)
    err_code = sd_ble_gap_scan_start(&scan_params, &m_scan_buffer);
#else
    err_code = sd_ble_gap_scan_start(&scan_params);
#endif

    if (err_code != NRF_SUCCESS) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
            "Failed to start scanning, status: 0x%0xlX", err_code));
    }

    while (device->conn_handle == BLE_CONN_HANDLE_INVALID) {
#ifdef MICROPY_VM_HOOK_LOOP
    MICROPY_VM_HOOK_LOOP
#endif
    }

    // TODO: read name

    if (m_discovery_mutex == NULL) {
        m_discovery_mutex = m_new_ll(nrf_mutex_t, 1);

        err_code = sd_mutex_new(m_discovery_mutex);
        if (err_code != NRF_SUCCESS) {
            nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_OSError,
                "Failed to create mutex, status: 0x%0xlX", err_code));
        }
    }

    // find services
    bool found_service = discover_services(device, BLE_GATT_HANDLE_START);
    while (found_service) {
        const mp_obj_list_t *service_list = MP_OBJ_TO_PTR(device->service_list);
        const bleio_service_obj_t *service = service_list->items[service_list->len - 1];

        found_service = discover_services(device, service->end_handle + 1);
    }

    // find characteristics in each service
    const mp_obj_list_t *service_list = MP_OBJ_TO_PTR(device->service_list);
    for (size_t i = 0; i < service_list->len; ++i) {
        bleio_service_obj_t *service = service_list->items[i];

        bool found_char = discover_characteristics(device, service, service->start_handle);
        while (found_char) {
            const mp_obj_list_t *char_list = MP_OBJ_TO_PTR(service->char_list);
            const bleio_characteristic_obj_t *characteristic = char_list->items[char_list->len - 1];

            const uint16_t next_handle = characteristic->handle + 1;
            if (next_handle >= service->end_handle) {
                break;
            }

            found_char = discover_characteristics(device, service, next_handle);
        }
    }
}

void common_hal_bleio_device_disconnect(bleio_device_obj_t *device) {
    sd_ble_gap_disconnect(device->conn_handle, BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
}