[Raspberry Pi Pico W] BTstack BLE Ep 4. HID over GATT -- Custom keypad HID device

本篇文章介紹HID over GATT device的製作。在前篇文章介紹classic HID custom keypad製作，但是若HID device移除電源後再接上電源，HID host不能再次自動連上。修改HID SDP paramter hid_reconnect_initiate=0後，雖然在Android與Linux Debian能運作正常，但在iPhone與Windows下卻無法正常運作。

本篇文章測試HID over GATT是否能正常運作。

一、HID over GATT:

在HID over GATT profile文件中說明, HID device需具備三個必要services: HID service, battery service and device information service。 如下圖所示。

(source SIG HID over GATT profile)

 此三種service在BTstack library中均有implement。宣告GATT service時直接import即可。

在CMakeLists.txt中加pico_btstack_make_gatt_header指令產生ATT database。

二、定義hid advertising data:

HID device Class of service UUID and HID keyboard APPERANCE可由SIG assigned numbers文件查出，別為0x1812與0x03C1。

三、定義HID device keyboard descriptior:

hid keyboard descriptor定義input data為：modifier(1 byte), reserved byte(1 byte)與keycode(6 bytes)。output data為:5 bits+3 bits。

四、定義輸入ascii character與scan code對照表:

由HID report input 輸入的character需轉為scan code。

五、初始化所需的driver與註冊event handler:

六、程式主要流程：

1. 由keypad輸入字元：get_new_keypad_value() ：定義在4x4 keypad driver中。
2. 字元存入ring buffer中，並呼叫hids_device_request_can_send_now_event(): key_input()。
3. 在HIDS_SUBEVENT_CAN_SEND_NOW將字元的modifier與keycode送出：typing_can_send_now();
4. typing_can_send_now()：由ring buffer讀取輸入的字元，查表取得modifier與keycode，呼叫send_report(modifier, keycode)，送出hid report後，再次呼叫hids_device_request_can_send_now_event()執行下次送出hid report。
5. send_report():
   uint8_t report[] = {  modifier, 0, keycode, 0, 0, 0, 0, 0};
   送出HID descriptor所定義的input的8 bytes。

詳細程式碼附於文末。

七、成果展示影片：

八、程式碼：

    pico_keypad library程式碼，請參閱前篇文章內容。

• hog_custom_keypad.c

/* this file was modified from hog_keyboard_demo.c */
/*
 * Copyright (C) 2014 BlueKitchen GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 * 4. Any redistribution, use, or modification is done solely for
 *    personal benefit and not for any commercial purpose or for
 *    monetary gain.
 *
 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BLUEKITCHEN
 * GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Please inquire about commercial licensing options at
 * contact@bluekitchen-gmbh.com
 *
 */
 #include <stdio.h>
#include "pico/stdlib.h"
#include "pico/cyw43_arch.h"
#include "btstack.h"

#include "ble/gatt-service/battery_service_server.h"
#include "ble/gatt-service/device_information_service_server.h"
#include "ble/gatt-service/hids_device.h"

#include "hog_custom_keypad.h"
#include "inttypes.h"
#include "keypad.h"

#define BACKSPACE_BUTTON   16
#define RETURN_BUTTON 17

// from USB HID Specification 1.1, Appendix B.1
const uint8_t hid_descriptor_keyboard_boot_mode[] = {

    0x05, 0x01,                    // Usage Page (Generic Desktop)
    0x09, 0x06,                    // Usage (Keyboard)
    0xa1, 0x01,                    // Collection (Application)

    0x85,  0x01,                   // Report ID 1

    // Modifier byte

    0x75, 0x01,                    //   Report Size (1)
    0x95, 0x08,                    //   Report Count (8)
    0x05, 0x07,                    //   Usage Page (Key codes)
    0x19, 0xe0,                    //   Usage Minimum (Keyboard LeftControl)
    0x29, 0xe7,                    //   Usage Maxium (Keyboard Right GUI)
    0x15, 0x00,                    //   Logical Minimum (0)
    0x25, 0x01,                    //   Logical Maximum (1)
    0x81, 0x02,                    //   Input (Data, Variable, Absolute)

    // Reserved byte

    0x75, 0x01,                    //   Report Size (1)
    0x95, 0x08,                    //   Report Count (8)
    0x81, 0x03,                    //   Input (Constant, Variable, Absolute)

    // LED report + padding

    0x95, 0x05,                    //   Report Count (5)
    0x75, 0x01,                    //   Report Size (1)
    0x05, 0x08,                    //   Usage Page (LEDs)
    0x19, 0x01,                    //   Usage Minimum (Num Lock)
    0x29, 0x05,                    //   Usage Maxium (Kana)
    0x91, 0x02,                    //   Output (Data, Variable, Absolute)

    0x95, 0x01,                    //   Report Count (1)
    0x75, 0x03,                    //   Report Size (3)
    0x91, 0x03,                    //   Output (Constant, Variable, Absolute)

    // Keycodes

    0x95, 0x06,                    //   Report Count (6)
    0x75, 0x08,                    //   Report Size (8)
    0x15, 0x00,                    //   Logical Minimum (0)
    0x25, 0xff,                    //   Logical Maximum (1)
    0x05, 0x07,                    //   Usage Page (Key codes)
    0x19, 0x00,                    //   Usage Minimum (Reserved (no event indicated))
    0x29, 0xff,                    //   Usage Maxium (Reserved)
    0x81, 0x00,                    //   Input (Data, Array)

    0xc0,                          // End collection
};

//
#define CHAR_ILLEGAL     0xff
#define CHAR_RETURN     '\n'
#define CHAR_ESCAPE      27
#define CHAR_TAB         '\t'
#define CHAR_BACKSPACE   0x7f

// Simplified US Keyboard with Shift modifier

/**
 * English (US)
 */
static const uint8_t keytable_us_none [] = {
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /*   0-3 */
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',                   /*  4-13 */
    'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',                   /* 14-23 */
    'u', 'v', 'w', 'x', 'y', 'z',                                       /* 24-29 */
    '1', '2', '3', '4', '5', '6', '7', '8', '9', '0',                   /* 30-39 */
    CHAR_RETURN, CHAR_ESCAPE, CHAR_BACKSPACE, CHAR_TAB, ' ',            /* 40-44 */
    '-', '=', '[', ']', '\\', CHAR_ILLEGAL, ';', '\'', 0x60, ',',       /* 45-54 */
    '.', '/', CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,   /* 55-60 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 61-64 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 65-68 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 69-72 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 73-76 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 77-80 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 81-84 */
    '*', '-', '+', '\n', '1', '2', '3', '4', '5',                       /* 85-97 */
    '6', '7', '8', '9', '0', '.', 0xa7,                                 /* 97-100 */
};

static const uint8_t keytable_us_shift[] = {
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /*  0-3  */
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',                   /*  4-13 */
    'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',                   /* 14-23 */
    'U', 'V', 'W', 'X', 'Y', 'Z',                                       /* 24-29 */
    '!', '@', '#', '$', '%', '^', '&', '*', '(', ')',                   /* 30-39 */
    CHAR_RETURN, CHAR_ESCAPE, CHAR_BACKSPACE, CHAR_TAB, ' ',            /* 40-44 */
    '_', '+', '{', '}', '|', CHAR_ILLEGAL, ':', '"', 0x7E, '<',         /* 45-54 */
    '>', '?', CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,   /* 55-60 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 61-64 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 65-68 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 69-72 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 73-76 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 77-80 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 81-84 */
    '*', '-', '+', '\n', '1', '2', '3', '4', '5',                       /* 85-97 */
    '6', '7', '8', '9', '0', '.', 0xb1,                                 /* 97-100 */
};

static btstack_packet_callback_registration_t hci_event_callback_registration;
static btstack_packet_callback_registration_t sm_event_callback_registration;
static uint8_t battery = 100;
static hci_con_handle_t con_handle = HCI_CON_HANDLE_INVALID;
static uint8_t protocol_mode = HID_PROTOCOL_MODE_REPORT;

const uint8_t adv_data[] = {
    // Flags general discoverable, BR/EDR not supported
    0x02, BLUETOOTH_DATA_TYPE_FLAGS, 0x06,
    // Name
    0x0d, BLUETOOTH_DATA_TYPE_COMPLETE_LOCAL_NAME, 'H', 'I', 'D', ' ', 'K', 'e', 'y', 'b', 'o', 'a', 'r', 'd',
    // 16-bit Service UUIDs
    0x03, BLUETOOTH_DATA_TYPE_COMPLETE_LIST_OF_16_BIT_SERVICE_CLASS_UUIDS, 
                ORG_BLUETOOTH_SERVICE_HUMAN_INTERFACE_DEVICE & 0xff, ORG_BLUETOOTH_SERVICE_HUMAN_INTERFACE_DEVICE >> 8,
    // Appearance HID - Keyboard (Category 15, Sub-Category 1)
    0x03, BLUETOOTH_DATA_TYPE_APPEARANCE, 0xC1, 0x03,
};
const uint8_t adv_data_len = sizeof(adv_data);

// Buffer for 30 characters
static uint8_t key_input_storage[30];
static btstack_ring_buffer_t key_input_buffer;

// HID Keyboard lookup
static int lookup_keycode(uint8_t character, const uint8_t * table, int size, uint8_t * keycode){
    int i;
    for (i=0;i<size;i++){
        if (table[i] != character) continue;
        *keycode = i;
        return 1;
    }
    return 0;
}

static int keycode_and_modifer_us_for_character(uint8_t character, uint8_t * keycode, uint8_t * modifier){
    int found;
    found = lookup_keycode(character, keytable_us_none, sizeof(keytable_us_none), keycode);
    if (found) {
        *modifier = 0;  // none
        return 1;
    }
    found = lookup_keycode(character, keytable_us_shift, sizeof(keytable_us_shift), keycode);
    if (found) {
        *modifier = 2;  // shift
        return 1;
    }
    return 0;
}

// HID Report sending
static void send_report(int modifier, int keycode){
    uint8_t report[] = {  modifier, 0, keycode, 0, 0, 0, 0, 0};
    switch (protocol_mode){
        case 0:
            hids_device_send_boot_keyboard_input_report(con_handle, report, sizeof(report));
            break;
        case 1:
           hids_device_send_input_report(con_handle, report, sizeof(report));
           break;
        default:
            break;
    }
}

static enum {
    W4_INPUT,
    W4_CAN_SEND_FROM_BUFFER,
    W4_CAN_SEND_KEY_UP,
} state;


static void typing_can_send_now(void){
    switch (state){
        case W4_CAN_SEND_FROM_BUFFER:
            while (1){
                uint8_t c;
                uint32_t num_bytes_read;

                btstack_ring_buffer_read(&key_input_buffer, &c, 1, &num_bytes_read);
                if (num_bytes_read == 0){
                    state = W4_INPUT;
                    break;
                }

                uint8_t modifier;
                uint8_t keycode;
                int found = keycode_and_modifer_us_for_character(c, &keycode, &modifier);
                if (!found) continue;

                printf("sending: %c\n", c);

                send_report(modifier, keycode);
                state = W4_CAN_SEND_KEY_UP;
                hids_device_request_can_send_now_event(con_handle);
                break;
            }
            break;
        case W4_CAN_SEND_KEY_UP:
            send_report(0, 0);
            if (btstack_ring_buffer_bytes_available(&key_input_buffer)){
                state = W4_CAN_SEND_FROM_BUFFER;
                hids_device_request_can_send_now_event(con_handle);
            } else {
                state = W4_INPUT;
            }
            break;
        default:
            break;
    }
}

void key_input(char character){
    uint8_t c = character;
    btstack_ring_buffer_write(&key_input_buffer, &c, 1);
    // start sending
    if (state == W4_INPUT && con_handle != HCI_CON_HANDLE_INVALID){
        state = W4_CAN_SEND_FROM_BUFFER;
        hids_device_request_can_send_now_event(con_handle);
    }
}

static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    UNUSED(channel);
    UNUSED(size);

    if (packet_type != HCI_EVENT_PACKET) return;

    switch (hci_event_packet_get_type(packet)) {
        case HCI_EVENT_DISCONNECTION_COMPLETE:
            con_handle = HCI_CON_HANDLE_INVALID;
            printf("Disconnected\n");
            break;
        case SM_EVENT_JUST_WORKS_REQUEST:
            printf("Just Works requested\n");
            sm_just_works_confirm(sm_event_just_works_request_get_handle(packet));
            break;
        case SM_EVENT_NUMERIC_COMPARISON_REQUEST:
            printf("Confirming numeric comparison: %"PRIu32"\n", sm_event_numeric_comparison_request_get_passkey(packet));
            sm_numeric_comparison_confirm(sm_event_passkey_display_number_get_handle(packet));
            break;
        case SM_EVENT_PASSKEY_DISPLAY_NUMBER:
            printf("Display Passkey: %"PRIu32"\n", sm_event_passkey_display_number_get_passkey(packet));
            break;
        case HCI_EVENT_HIDS_META:
            switch (hci_event_hids_meta_get_subevent_code(packet)){
                case HIDS_SUBEVENT_INPUT_REPORT_ENABLE:
                    con_handle = hids_subevent_input_report_enable_get_con_handle(packet);
                    printf("Report Characteristic Subscribed %u\n", hids_subevent_input_report_enable_get_enable(packet));
                    break;
                case HIDS_SUBEVENT_BOOT_KEYBOARD_INPUT_REPORT_ENABLE:
                    con_handle = hids_subevent_boot_keyboard_input_report_enable_get_con_handle(packet);
                    printf("Boot Keyboard Characteristic Subscribed %u\n", hids_subevent_boot_keyboard_input_report_enable_get_enable(packet));
                    break;
                case HIDS_SUBEVENT_PROTOCOL_MODE:
                    protocol_mode = hids_subevent_protocol_mode_get_protocol_mode(packet);
                    printf("Protocol Mode: %s mode\n", hids_subevent_protocol_mode_get_protocol_mode(packet) ? "Report" : "Boot");
                    break;
                case HIDS_SUBEVENT_CAN_SEND_NOW:
                    typing_can_send_now();
                    break;
                default:
                    break;
            }
            break;
            
        default:
            break;
    }
}

void key_button_callback(uint gpio, uint32_t events) {
    gpio_set_irq_enabled(gpio, GPIO_IRQ_EDGE_FALL, false);
    gpio_acknowledge_irq(gpio, events);
    
    if (gpio == BACKSPACE_BUTTON ) {       
        busy_wait_ms(100);
        printf("%d\n", events);
        
        key_input(CHAR_BACKSPACE); //Backspace key
        
    }
    if (gpio == RETURN_BUTTON) {
        busy_wait_ms(200);
        key_input(CHAR_RETURN); // return key
        
    }
    gpio_set_irq_enabled(gpio, GPIO_IRQ_EDGE_FALL, true);

}


int main()
{
    stdio_init_all();
    if (cyw43_arch_init()) {
        printf("cyw43_arch_init error\n");
        return 0;
    }
    //0. initialize keypad
    keypad_init();

    // backspace & return key
    gpio_init(BACKSPACE_BUTTON);
    gpio_init(RETURN_BUTTON);
    gpio_pull_up(BACKSPACE_BUTTON);
    gpio_pull_up(RETURN_BUTTON);
    gpio_set_irq_enabled_with_callback(BACKSPACE_BUTTON, GPIO_IRQ_EDGE_FALL, true, key_button_callback);
    gpio_set_irq_enabled_with_callback(RETURN_BUTTON, GPIO_IRQ_EDGE_FALL, true, key_button_callback);

    //1. initialize ring buffer for key input
    btstack_ring_buffer_init(&key_input_buffer, key_input_storage, sizeof(key_input_storage));
    
    //2. l2cap initialize
    l2cap_init();

    //3. setup SM: Display only
    sm_init();
    sm_set_io_capabilities(IO_CAPABILITY_NO_INPUT_NO_OUTPUT);
    sm_set_authentication_requirements(SM_AUTHREQ_SECURE_CONNECTION | SM_AUTHREQ_BONDING);

    //4. setup ATT server
    att_server_init(profile_data, NULL, NULL);

    //5. setup battery service
    battery_service_server_init(battery);

    //6. setup device information service
    device_information_service_server_init();

    //7. setup HID Device service
    hids_device_init(0, hid_descriptor_keyboard_boot_mode, sizeof(hid_descriptor_keyboard_boot_mode));

    //8. setup advertisements
    uint16_t adv_int_min = 0x0030;
    uint16_t adv_int_max = 0x0030;
    uint8_t adv_type = 0;
    bd_addr_t null_addr;
    memset(null_addr, 0, 6);
    gap_advertisements_set_params(adv_int_min, adv_int_max, adv_type, 0, null_addr, 0x07, 0x00);
    gap_advertisements_set_data(adv_data_len, (uint8_t*) adv_data);
    gap_advertisements_enable(1);

    //9. register for HCI events
    hci_event_callback_registration.callback = &packet_handler;
    hci_add_event_handler(&hci_event_callback_registration);

    //10. register for SM events
    sm_event_callback_registration.callback = &packet_handler;
    sm_add_event_handler(&sm_event_callback_registration);

    //11. register for HIDS
    hids_device_register_packet_handler(packet_handler);

    hci_power_control(HCI_POWER_ON);

    uint8_t c;
    while(1) {
        if (con_handle == HCI_CON_HANDLE_INVALID) continue;
        c=get_new_keypad_value();
        if (c) {
            key_input(c);
        }
    }

    return 0;
}

• hog_custom_keypad.gatt

PRIMARY_SERVICE, GAP_SERVICE
CHARACTERISTIC, GAP_DEVICE_NAME, READ, "HID Keyboard"
CHARACTERISTIC, GATT_DATABASE_HASH, READ,

// add Battery Service
#import <battery_service.gatt>

// add Device ID Service
#import <device_information_service.gatt>

// add HID Service
#import <hids.gatt>

• CMakeLists.txt

# Generated Cmake Pico project file

cmake_minimum_required(VERSION 3.13)

set(CMAKE_C_STANDARD 11)
set(CMAKE_CXX_STANDARD 17)

# Initialise pico_sdk from installed location
# (note this can come from environment, CMake cache etc)
set(PICO_SDK_PATH "/home/duser/pico/pico-sdk")

set(PICO_BOARD pico_w CACHE STRING "Board type")

# Pull in Raspberry Pi Pico SDK (must be before project)
include(pico_sdk_import.cmake)

if (PICO_SDK_VERSION_STRING VERSION_LESS "1.4.0")
  message(FATAL_ERROR "Raspberry Pi Pico SDK version 1.4.0 (or later) required. Your version is ${PICO_SDK_VERSION_STRING}")
endif()

project(hog_custom_keypad C CXX ASM)

# Initialise the Raspberry Pi Pico SDK
pico_sdk_init()

# Add executable. Default name is the project name, version 0.1

add_executable(hog_custom_keypad hog_custom_keypad.c )

pico_set_program_name(hog_custom_keypad "hog_custom_keypad")
pico_set_program_version(hog_custom_keypad "0.1")

pico_enable_stdio_uart(hog_custom_keypad 1)
pico_enable_stdio_usb(hog_custom_keypad 0)

# Add the standard library to the build
target_link_libraries(hog_custom_keypad
        pico_stdlib
        pico_cyw43_arch_none
        pico_btstack_cyw43
        pico_btstack_ble)

# Add the standard include files to the build
target_include_directories(hog_custom_keypad PRIVATE
  ${CMAKE_CURRENT_LIST_DIR}
  ${CMAKE_CURRENT_LIST_DIR}/.. # for our common lwipopts or any other standard includes, if required
)
pico_btstack_make_gatt_header(hog_custom_keypad PRIVATE "${CMAKE_CURRENT_LIST_DIR}/hog_custom_keypad.gatt")


# Add any user requested libraries
add_subdirectory(pico_keypad)
target_link_libraries(hog_custom_keypad 
        pico_keypad)
        
pico_add_extra_outputs(hog_custom_keypad)

• btstack_config.h

#ifndef _PICO_BTSTACK_BTSTACK_CONFIG_H
#define _PICO_BTSTACK_BTSTACK_CONFIG_H

// BTstack features that can be enabled
#ifdef ENABLE_BLE
#define ENABLE_LE_PERIPHERAL
#define ENABLE_LE_CENTRAL
#define ENABLE_L2CAP_LE_CREDIT_BASED_FLOW_CONTROL_MODE
#endif

#ifdef ENABLE_MESH
// Mesh Config
#define ENABLE_MESH_ADV_BEARER
#define ENABLE_MESH_GATT_BEARER
#define ENABLE_MESH_PB_ADV
#define ENABLE_MESH_PB_GATT
#define ENABLE_MESH_PROXY_SERVER
#define ENABLE_MESH_RELAY

#define ENABLE_MESH_PROVISIONER

#define MAX_NR_MESH_SUBNETS            2
#define MAX_NR_MESH_TRANSPORT_KEYS    16
#define MAX_NR_MESH_VIRTUAL_ADDRESSES 16
// allow for one NetKey update
#define MAX_NR_MESH_NETWORK_KEYS      (MAX_NR_MESH_SUBNETS+1)
#endif 


#define ENABLE_LOG_INFO
#define ENABLE_LOG_ERROR
#define ENABLE_PRINTF_HEXDUMP
#define ENABLE_SCO_OVER_HCI

// BTstack configuration. buffers, sizes, ...
#define HCI_OUTGOING_PRE_BUFFER_SIZE 4
#define HCI_ACL_PAYLOAD_SIZE (1691 + 4)
#define HCI_ACL_CHUNK_SIZE_ALIGNMENT 4
#define MAX_NR_AVDTP_CONNECTIONS 1
#define MAX_NR_AVDTP_STREAM_ENDPOINTS 1
#define MAX_NR_AVRCP_CONNECTIONS 2
#define MAX_NR_BNEP_CHANNELS 1
#define MAX_NR_BNEP_SERVICES 1
#define MAX_NR_BTSTACK_LINK_KEY_DB_MEMORY_ENTRIES  2
#define MAX_NR_GATT_CLIENTS 1
#define MAX_NR_HCI_CONNECTIONS 2
#define MAX_NR_HID_HOST_CONNECTIONS 1
#define MAX_NR_HIDS_CLIENTS 1
#define MAX_NR_HFP_CONNECTIONS 1
#define MAX_NR_L2CAP_CHANNELS  4
#define MAX_NR_L2CAP_SERVICES  3
#define MAX_NR_RFCOMM_CHANNELS 1
#define MAX_NR_RFCOMM_MULTIPLEXERS 1
#define MAX_NR_RFCOMM_SERVICES 1
#define MAX_NR_SERVICE_RECORD_ITEMS 4
#define MAX_NR_SM_LOOKUP_ENTRIES 3
#define MAX_NR_WHITELIST_ENTRIES 16
#define MAX_NR_LE_DEVICE_DB_ENTRIES 16

// Limit number of ACL/SCO Buffer to use by stack to avoid cyw43 shared bus overrun
#define MAX_NR_CONTROLLER_ACL_BUFFERS 3
#define MAX_NR_CONTROLLER_SCO_PACKETS 3

// Enable and configure HCI Controller to Host Flow Control to avoid cyw43 shared bus overrun
#define ENABLE_HCI_CONTROLLER_TO_HOST_FLOW_CONTROL
#define HCI_HOST_ACL_PACKET_LEN 1024
#define HCI_HOST_ACL_PACKET_NUM 3
#define HCI_HOST_SCO_PACKET_LEN 120
#define HCI_HOST_SCO_PACKET_NUM 3

// Link Key DB and LE Device DB using TLV on top of Flash Sector interface
#define NVM_NUM_DEVICE_DB_ENTRIES 16
#define NVM_NUM_LINK_KEYS 16

// We don't give btstack a malloc, so use a fixed-size ATT DB.
#define MAX_ATT_DB_SIZE 512

// BTstack HAL configuration
#define HAVE_EMBEDDED_TIME_MS

// map btstack_assert onto Pico SDK assert()
#define HAVE_ASSERT

// Some USB dongles take longer to respond to HCI reset (e.g. BCM20702A).
#define HCI_RESET_RESEND_TIMEOUT_MS 1000

#define ENABLE_SOFTWARE_AES128
#define ENABLE_MICRO_ECC_FOR_LE_SECURE_CONNECTIONS

//#define HAVE_BTSTACK_STDIN

// To get the audio demos working even with HCI dump at 115200, this truncates long ACL packets
//#define HCI_DUMP_STDOUT_MAX_SIZE_ACL 100

#ifdef ENABLE_CLASSIC
#define ENABLE_L2CAP_ENHANCED_RETRANSMISSION_MODE
#endif

#define HAVE_MALLOC

// BTstack configuration. buffers, sizes, ...

#define HCI_INCOMING_PRE_BUFFER_SIZE 6


  #endif // _PICO_BTSTACK_BTSTACK_CONFIG_H

[Raspberry Pi Pico W] BTstack: Ep 5. Bluetooth HID Host

本篇文章介紹Bluetooth HID host的製作，修改BTstack hid_host_deco.c example code。

hid device(hid keyboard)使用前篇文章介紹，hid host接受hid device送來hid report顯示字元在tft display上，當按下F1鍵按鈕時清除tft display內容。

詳細製作過程請參閱「成果影片」。

詳細程式碼附於文章末尾。

• 成果影片

• 程式碼
  
  
• btstack_config.h

 #ifndef _PICO_BTSTACK_BTSTACK_CONFIG_H
#define _PICO_BTSTACK_BTSTACK_CONFIG_H

// BTstack features that can be enabled
#ifdef ENABLE_BLE
#define ENABLE_LE_PERIPHERAL
#define ENABLE_LE_CENTRAL
#define ENABLE_L2CAP_LE_CREDIT_BASED_FLOW_CONTROL_MODE
#endif

#ifdef ENABLE_MESH
// Mesh Config
#define ENABLE_MESH_ADV_BEARER
#define ENABLE_MESH_GATT_BEARER
#define ENABLE_MESH_PB_ADV
#define ENABLE_MESH_PB_GATT
#define ENABLE_MESH_PROXY_SERVER
#define ENABLE_MESH_RELAY

#define ENABLE_MESH_PROVISIONER

#define MAX_NR_MESH_SUBNETS            2
#define MAX_NR_MESH_TRANSPORT_KEYS    16
#define MAX_NR_MESH_VIRTUAL_ADDRESSES 16
// allow for one NetKey update
#define MAX_NR_MESH_NETWORK_KEYS      (MAX_NR_MESH_SUBNETS+1)
#endif 


#define ENABLE_LOG_INFO
#define ENABLE_LOG_ERROR
#define ENABLE_PRINTF_HEXDUMP
#define ENABLE_SCO_OVER_HCI

// BTstack configuration. buffers, sizes, ...
#define HCI_OUTGOING_PRE_BUFFER_SIZE 4
#define HCI_ACL_PAYLOAD_SIZE (1691 + 4)
#define HCI_ACL_CHUNK_SIZE_ALIGNMENT 4
#define MAX_NR_AVDTP_CONNECTIONS 1
#define MAX_NR_AVDTP_STREAM_ENDPOINTS 1
#define MAX_NR_AVRCP_CONNECTIONS 2
#define MAX_NR_BNEP_CHANNELS 1
#define MAX_NR_BNEP_SERVICES 1
#define MAX_NR_BTSTACK_LINK_KEY_DB_MEMORY_ENTRIES  2
#define MAX_NR_GATT_CLIENTS 1
#define MAX_NR_HCI_CONNECTIONS 2
#define MAX_NR_HID_HOST_CONNECTIONS 1
#define MAX_NR_HIDS_CLIENTS 1
#define MAX_NR_HFP_CONNECTIONS 1
#define MAX_NR_L2CAP_CHANNELS  4
#define MAX_NR_L2CAP_SERVICES  3
#define MAX_NR_RFCOMM_CHANNELS 1
#define MAX_NR_RFCOMM_MULTIPLEXERS 1
#define MAX_NR_RFCOMM_SERVICES 1
#define MAX_NR_SERVICE_RECORD_ITEMS 4
#define MAX_NR_SM_LOOKUP_ENTRIES 3
#define MAX_NR_WHITELIST_ENTRIES 16
#define MAX_NR_LE_DEVICE_DB_ENTRIES 16

// Limit number of ACL/SCO Buffer to use by stack to avoid cyw43 shared bus overrun
#define MAX_NR_CONTROLLER_ACL_BUFFERS 3
#define MAX_NR_CONTROLLER_SCO_PACKETS 3

// Enable and configure HCI Controller to Host Flow Control to avoid cyw43 shared bus overrun
#define ENABLE_HCI_CONTROLLER_TO_HOST_FLOW_CONTROL
#define HCI_HOST_ACL_PACKET_LEN 1024
#define HCI_HOST_ACL_PACKET_NUM 3
#define HCI_HOST_SCO_PACKET_LEN 120
#define HCI_HOST_SCO_PACKET_NUM 3

// Link Key DB and LE Device DB using TLV on top of Flash Sector interface
#define NVM_NUM_DEVICE_DB_ENTRIES 16
#define NVM_NUM_LINK_KEYS 16

// We don't give btstack a malloc, so use a fixed-size ATT DB.
#define MAX_ATT_DB_SIZE 512

// BTstack HAL configuration
#define HAVE_EMBEDDED_TIME_MS

// map btstack_assert onto Pico SDK assert()
#define HAVE_ASSERT

// Some USB dongles take longer to respond to HCI reset (e.g. BCM20702A).
#define HCI_RESET_RESEND_TIMEOUT_MS 1000

#define ENABLE_SOFTWARE_AES128
#define ENABLE_MICRO_ECC_FOR_LE_SECURE_CONNECTIONS

//#define HAVE_BTSTACK_STDIN

// To get the audio demos working even with HCI dump at 115200, this truncates long ACL packets
//#define HCI_DUMP_STDOUT_MAX_SIZE_ACL 100

#ifdef ENABLE_CLASSIC
#define ENABLE_L2CAP_ENHANCED_RETRANSMISSION_MODE
#endif

#define HAVE_MALLOC

#endif // _PICO_BTSTACK_BTSTACK_CONFIG_H

• CMakeLists.txt

 # Generated Cmake Pico project file

cmake_minimum_required(VERSION 3.13)

set(CMAKE_C_STANDARD 11)
set(CMAKE_CXX_STANDARD 17)

# Initialise pico_sdk from installed location
# (note this can come from environment, CMake cache etc)
set(PICO_SDK_PATH "/home/duser/pico/pico-sdk")

set(PICO_BOARD pico_w CACHE STRING "Board type")

# Pull in Raspberry Pi Pico SDK (must be before project)
include(pico_sdk_import.cmake)

if (PICO_SDK_VERSION_STRING VERSION_LESS "1.4.0")
  message(FATAL_ERROR "Raspberry Pi Pico SDK version 1.4.0 (or later) required. Your version is ${PICO_SDK_VERSION_STRING}")
endif()

project(picow_hid_host C CXX ASM)

# Initialise the Raspberry Pi Pico SDK
pico_sdk_init()

# Add executable. Default name is the project name, version 0.1

add_executable(picow_hid_host picow_hid_host.c hid_host_demo.c)

pico_set_program_name(picow_hid_host "picow_hid_host")
pico_set_program_version(picow_hid_host "0.1")

pico_enable_stdio_uart(picow_hid_host 0)
pico_enable_stdio_usb(picow_hid_host 1)

# Add the standard library to the build
target_link_libraries(picow_hid_host
        pico_stdlib
        pico_cyw43_arch_none
        pico_btstack_cyw43
        pico_btstack_classic)

# Add the standard include files to the build
target_include_directories(picow_hid_host PRIVATE
  ${CMAKE_CURRENT_LIST_DIR}
  ${CMAKE_CURRENT_LIST_DIR}/.. # for our common lwipopts or any other standard includes, if required
)
# add user library
add_subdirectory(pico_tft)
target_link_libraries(picow_hid_host
      pico_tft)

pico_add_extra_outputs(picow_hid_host)

• picow_hid_host.c

 #include <stdio.h>
#include "pico/stdlib.h"
#include "pico/cyw43_arch.h"

#include "pico_tft.h"

extern int btstack_main(int argc, const char * argv[]);
int main()
{
    stdio_init_all();
    if (cyw43_arch_init()) {
        puts("cyw43 init error");
        return 0;

    }
   
    tft_init();
    
    btstack_main(0, NULL);


    while(1) {
        tight_loop_contents();
    }


    return 0;
}

• hid_host_demo.c(modified)

 /*
 * Copyright (C) 2017 BlueKitchen GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 * 4. Any redistribution, use, or modification is done solely for
 *    personal benefit and not for any commercial purpose or for
 *    monetary gain.
 *
 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BLUEKITCHEN
 * GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Please inquire about commercial licensing options at 
 * contact@bluekitchen-gmbh.com
 *
 */

#define BTSTACK_FILE__ "hid_host_demo.c"

/*
 * hid_host_demo.c
 */

/* EXAMPLE_START(hid_host_demo): HID Host Classic
 *
 * @text This example implements a HID Host. For now, it connects to a fixed device.
 * It will connect in Report protocol mode if this mode is supported by the HID Device,
 * otherwise it will fall back to BOOT protocol mode. 
 */

#include <inttypes.h>
#include <stdio.h>

#include "btstack_config.h"
#include "btstack.h"

#define MAX_ATTRIBUTE_VALUE_SIZE 300

// HID device Bluetooth device address
/* modify begin */
static const char * remote_addr_string = "28:CD:C1:01:XX:XX";
/* modify end */
/* ===add tft display begin===*/
#include "pico_tft.h"
#include "tft_string.h"
#include "fonts/font_fixedsys_mono_24.h"

#define F1_KEY_SCAN_CODE           0x3a          // F1 key scan code
static uint8_t tft_x=0, tft_y=0;
void tft_dislplay_clean() {
    tft_fill_rect(0,0, TFT_WIDTH, TFT_HEIGHT, 0xffff);
    tft_x=0;
    tft_y=0;
}
void tft_display(uint8_t ch) {
    
    uint8_t ch_str[2];
    
    if (ch == '\n') {
        tft_x=0; tft_y+=25;
    } else {
        sprintf(ch_str, "%c", ch);
        tft_draw_string(tft_x, tft_y, ch_str, 0x001f, &font_fixedsys_mono_24);
        tft_x+=13;
        if (tft_x > TFT_WIDTH-13) {
            tft_y+=25;
            tft_x=0;
        }
    }
    if (tft_y > TFT_HEIGHT-25) tft_y=0;

}
/* ===add tft display end===*/
static bd_addr_t remote_addr;

static btstack_packet_callback_registration_t hci_event_callback_registration;

// Simplified US Keyboard with Shift modifier

#define CHAR_ILLEGAL     0xff
#define CHAR_RETURN     '\n'
#define CHAR_ESCAPE      27
#define CHAR_TAB         '\t'
#define CHAR_BACKSPACE   0x7f

/**
 * English (US)
 */
static const uint8_t keytable_us_none [] = {
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /*   0-3 */
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',                   /*  4-13 */
    'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',                   /* 14-23 */
    'u', 'v', 'w', 'x', 'y', 'z',                                       /* 24-29 */
    '1', '2', '3', '4', '5', '6', '7', '8', '9', '0',                   /* 30-39 */
    CHAR_RETURN, CHAR_ESCAPE, CHAR_BACKSPACE, CHAR_TAB, ' ',            /* 40-44 */
    '-', '=', '[', ']', '\\', CHAR_ILLEGAL, ';', '\'', 0x60, ',',       /* 45-54 */
    '.', '/', CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,   /* 55-60 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 61-64 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 65-68 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 69-72 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 73-76 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 77-80 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 81-84 */
    '*', '-', '+', '\n', '1', '2', '3', '4', '5',                       /* 85-97 */
    '6', '7', '8', '9', '0', '.', 0xa7,                                 /* 97-100 */
}; 

static const uint8_t keytable_us_shift[] = {
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /*  0-3  */
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',                   /*  4-13 */
    'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',                   /* 14-23 */
    'U', 'V', 'W', 'X', 'Y', 'Z',                                       /* 24-29 */
    '!', '@', '#', '$', '%', '^', '&', '*', '(', ')',                   /* 30-39 */
    CHAR_RETURN, CHAR_ESCAPE, CHAR_BACKSPACE, CHAR_TAB, ' ',            /* 40-44 */
    '_', '+', '{', '}', '|', CHAR_ILLEGAL, ':', '"', 0x7E, '<',         /* 45-54 */
    '>', '?', CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,   /* 55-60 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 61-64 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 65-68 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 69-72 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 73-76 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 77-80 */
    CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL, CHAR_ILLEGAL,             /* 81-84 */
    '*', '-', '+', '\n', '1', '2', '3', '4', '5',                       /* 85-97 */
    '6', '7', '8', '9', '0', '.', 0xb1,                                 /* 97-100 */
}; 

// SDP
static uint8_t hid_descriptor_storage[MAX_ATTRIBUTE_VALUE_SIZE];

// App
static enum {
    APP_IDLE,
    APP_CONNECTED
} app_state = APP_IDLE;

static uint16_t hid_host_cid = 0;
static bool     hid_host_descriptor_available = false;
//static hid_protocol_mode_t hid_host_report_mode = HID_PROTOCOL_MODE_REPORT_WITH_FALLBACK_TO_BOOT;
/* ===modify protocol begin=== */
static hid_protocol_mode_t hid_host_report_mode = HID_PROTOCOL_MODE_REPORT;   ////////////
/* ===modify protocol end=== */

/* @section Main application configuration
 *
 * @text In the application configuration, L2CAP and HID host are initialized, and the link policies 
 * are set to allow sniff mode and role change. 
 */

/* LISTING_START(PanuSetup): Panu setup */
static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);

static void hid_host_setup(void){

    // Initialize L2CAP
    l2cap_init();

#ifdef ENABLE_BLE
    // Initialize LE Security Manager. Needed for cross-transport key derivation
    sm_init();
#endif

    // Initialize HID Host
    hid_host_init(hid_descriptor_storage, sizeof(hid_descriptor_storage));
    hid_host_register_packet_handler(packet_handler);

    // Allow sniff mode requests by HID device and support role switch
    gap_set_default_link_policy_settings(LM_LINK_POLICY_ENABLE_SNIFF_MODE | LM_LINK_POLICY_ENABLE_ROLE_SWITCH);

    // try to become master on incoming connections
    hci_set_master_slave_policy(HCI_ROLE_MASTER);

    // register for HCI events
    hci_event_callback_registration.callback = &packet_handler;
    hci_add_event_handler(&hci_event_callback_registration);

    // Disable stdout buffering

    /* uncomment */
    //setvbuf(stdin, NULL, _IONBF, 0);
}
/* LISTING_END */

/*
 * @section HID Report Handler
 * 
 * @text Use BTstack's compact HID Parser to process incoming HID Report in Report protocol mode. 
 * Iterate over all fields and process fields with usage page = 0x07 / Keyboard
 * Check if SHIFT is down and process first character (don't handle multiple key presses)
 * 
 */

#define NUM_KEYS 12
static uint8_t last_keys[NUM_KEYS];
static void hid_host_handle_interrupt_report(const uint8_t * report, uint16_t report_len){
    // check if HID Input Report
    if (report_len < 1) return;
    if (*report != 0xa1) return;   
    report++;
    report_len--;
    
    btstack_hid_parser_t parser;
    btstack_hid_parser_init(&parser, 
        hid_descriptor_storage_get_descriptor_data(hid_host_cid), 
        hid_descriptor_storage_get_descriptor_len(hid_host_cid), 
        HID_REPORT_TYPE_INPUT, report, report_len);

    int shift = 0;
    uint8_t new_keys[NUM_KEYS];
    memset(new_keys, 0, sizeof(new_keys));
    int     new_keys_count = 0;
    while (btstack_hid_parser_has_more(&parser)){
        uint16_t usage_page;
        uint16_t usage;
        int32_t  value;
        btstack_hid_parser_get_field(&parser, &usage_page, &usage, &value);
        if (usage_page != 0x07) continue;   
        switch (usage){
            case 0xe1:
            case 0xe6:
                if (value){
                    shift = 1;
                }
                continue;
            case 0x00:
                continue;
            default:
                break;
        }
        if (usage >= sizeof(keytable_us_none)) continue;

        // store new keys
        new_keys[new_keys_count++] = (uint8_t) usage;

        // check if usage was used last time (and ignore in that case)
        int i;
        for (i=0;i<NUM_KEYS;i++){
            if (usage == last_keys[i]){
                usage = 0;
            }
        }
        if (usage == 0) continue;

        uint8_t key;
        /* ===check F1_KEY====*/
        if (usage == F1_KEY_SCAN_CODE) { 
            tft_dislplay_clean();
            continue;
        }
        /* ===check F1_KEY====*/
        if (shift){
            key = keytable_us_shift[usage];
        } else {
            key = keytable_us_none[usage];
        }
        if (key == CHAR_ILLEGAL) continue;
        if (key == CHAR_BACKSPACE){ 
            printf("\b \b");    // go back one char, print space, go back one char again
            continue;
        }
        printf("%c", key);
        /* === modify for our Application begin===*/  
        tft_display(key);
        /* === modify for our Application end===*/
    }
    memcpy(last_keys, new_keys, NUM_KEYS);
}

/*
 * @section Packet Handler
 * 
 * @text The packet handler responds to various HID events.
 */

/* LISTING_START(packetHandler): Packet Handler */
static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size)
{
    /* LISTING_PAUSE */
    UNUSED(channel);
    UNUSED(size);

    uint8_t   event;
    bd_addr_t event_addr;
    uint8_t   status;

    /* LISTING_RESUME */
    switch (packet_type) {
		case HCI_EVENT_PACKET:
            event = hci_event_packet_get_type(packet);
            
            switch (event) {            
#ifndef HAVE_BTSTACK_STDIN
                /* @text When BTSTACK_EVENT_STATE with state HCI_STATE_WORKING
                 * is received and the example is started in client mode, the remote SDP HID query is started.
                 */
                case BTSTACK_EVENT_STATE:
                    if (btstack_event_state_get_state(packet) == HCI_STATE_WORKING){
                        status = hid_host_connect(remote_addr, hid_host_report_mode, &hid_host_cid);
                        if (status != ERROR_CODE_SUCCESS){
                            printf("HID host connect failed, status 0x%02x.\n", status);
                        } 
                    }
                    break;
#endif
                /* LISTING_PAUSE */
                case HCI_EVENT_PIN_CODE_REQUEST:
					// inform about pin code request
                    printf("Pin code request - using '0000'\n");
                    hci_event_pin_code_request_get_bd_addr(packet, event_addr);
                    gap_pin_code_response(event_addr, "0000");
					break;

                case HCI_EVENT_USER_CONFIRMATION_REQUEST:
                    // inform about user confirmation request
                    printf("SSP User Confirmation Request with numeric value '%"PRIu32"'\n", little_endian_read_32(packet, 8));
                    printf("SSP User Confirmation Auto accept\n");
                    break;

                /* LISTING_RESUME */
                case HCI_EVENT_HID_META:
                    switch (hci_event_hid_meta_get_subevent_code(packet)){

                        case HID_SUBEVENT_INCOMING_CONNECTION:
                            // There is an incoming connection: we can accept it or decline it.
                            // The hid_host_report_mode in the hid_host_accept_connection function 
                            // allows the application to request a protocol mode. 
                            // For available protocol modes, see hid_protocol_mode_t in btstack_hid.h file. 
                            hid_host_accept_connection(hid_subevent_incoming_connection_get_hid_cid(packet), hid_host_report_mode);
                            break;
                        
                        case HID_SUBEVENT_CONNECTION_OPENED:
                            // The status field of this event indicates if the control and interrupt
                            // connections were opened successfully.
                            status = hid_subevent_connection_opened_get_status(packet);
                            if (status != ERROR_CODE_SUCCESS) {
                                printf("Connection failed, status 0x%02x\n", status);
                                
                                app_state = APP_IDLE;
                                hid_host_cid = 0;
                                return;
                            }
                            app_state = APP_CONNECTED;
                            hid_host_descriptor_available = false;
                            hid_host_cid = hid_subevent_connection_opened_get_hid_cid(packet);
                            printf("HID Host connected.\n");
                            break;

                        case HID_SUBEVENT_DESCRIPTOR_AVAILABLE:
                            // This event will follows HID_SUBEVENT_CONNECTION_OPENED event. 
                            // For incoming connections, i.e. HID Device initiating the connection,
                            // the HID_SUBEVENT_DESCRIPTOR_AVAILABLE is delayed, and some HID  
                            // reports may be received via HID_SUBEVENT_REPORT event. It is up to 
                            // the application if these reports should be buffered or ignored until 
                            // the HID descriptor is available.
                            status = hid_subevent_descriptor_available_get_status(packet);
                            if (status == ERROR_CODE_SUCCESS){
                                hid_host_descriptor_available = true;
                                printf("HID Descriptor available, please start typing.\n");
                                tft_dislplay_clean();
                            } else {
                                printf("Cannot handle input report, HID Descriptor is not available, status 0x%02x\n", status);
                            }
                            break;

                        case HID_SUBEVENT_REPORT:
                            // Handle input report.
                            if (hid_host_descriptor_available){
                                hid_host_handle_interrupt_report(hid_subevent_report_get_report(packet), hid_subevent_report_get_report_len(packet));
                            } else {
                                printf_hexdump(hid_subevent_report_get_report(packet), hid_subevent_report_get_report_len(packet));
                            }
                            break;

                        case HID_SUBEVENT_SET_PROTOCOL_RESPONSE:
                            // For incoming connections, the library will set the protocol mode of the
                            // HID Device as requested in the call to hid_host_accept_connection. The event 
                            // reports the result. For connections initiated by calling hid_host_connect, 
                            // this event will occur only if the established report mode is boot mode.
                            status = hid_subevent_set_protocol_response_get_handshake_status(packet);
                            if (status != HID_HANDSHAKE_PARAM_TYPE_SUCCESSFUL){
                                printf("Error set protocol, status 0x%02x\n", status);
                                break;
                            }
                            switch ((hid_protocol_mode_t)hid_subevent_set_protocol_response_get_protocol_mode(packet)){
                                case HID_PROTOCOL_MODE_BOOT:
                                    printf("Protocol mode set: BOOT.\n");
                                    break;  
                                case HID_PROTOCOL_MODE_REPORT:
                                    printf("Protocol mode set: REPORT.\n");
                                    break;
                                default:
                                    printf("Unknown protocol mode.\n");
                                    break; 
                            }
                            break;

                        case HID_SUBEVENT_CONNECTION_CLOSED:
                            // The connection was closed.
                            hid_host_cid = 0;
                            hid_host_descriptor_available = false;
                            printf("HID Host disconnected.\n");
                            break;
                        
                        default:
                            break;
                    }
                    break;
                default:
                    break;
            }
            break;
        default:
            break;
    }
}
/* LISTING_END */

#ifdef HAVE_BTSTACK_STDIN
static void show_usage(void){
    bd_addr_t      iut_address;
    gap_local_bd_addr(iut_address);
    printf("\n--- Bluetooth HID Host Console %s ---\n", bd_addr_to_str(iut_address));
    printf("c      - Connect to %s in report mode, with fallback to boot mode.\n", remote_addr_string);
    printf("C      - Disconnect\n");
    
    printf("\n");
    printf("Ctrl-c - exit\n");
    printf("---\n");
}

static void stdin_process(char cmd){
    uint8_t status = ERROR_CODE_SUCCESS;
    switch (cmd){
        case 'c':
            printf("Connect to %s in report mode, with fallback to boot mode.\n", remote_addr_string);
            status = hid_host_connect(remote_addr, hid_host_report_mode, &hid_host_cid);
            break;
        case 'C':
            printf("Disconnect...\n");
            hid_host_disconnect(hid_host_cid);
            break;
        case '\n':
        case '\r':
            break;
        default:
            show_usage();
            break;
    }
    if (status != ERROR_CODE_SUCCESS){
        printf("HID host cmd \'%c\' failed, status 0x%02x\n", cmd, status);
    }
}
#endif

int btstack_main(int argc, const char * argv[]);
int btstack_main(int argc, const char * argv[]){

    (void)argc;
    (void)argv;

    hid_host_setup();

    // parse human readable Bluetooth address
    sscanf_bd_addr(remote_addr_string, remote_addr);

#ifdef HAVE_BTSTACK_STDIN
    btstack_stdin_setup(stdin_process);
#endif

    // Turn on the device 
    hci_power_control(HCI_POWER_ON);
    return 0;
}

/* EXAMPLE_END */