WiFiBoy32 + WB32-SFX BLE-MIDI 數位音源實驗成功!


  • wbo

    2017-10-28 by Derek w/ESP32徹底研究小組

    最近正在開發中的 WB32-SFX 真的是一個很有趣的 ESP32 應用開發板,除了可以做出 WiFi Web Radio 接收網路廣播,解 Live Streaming,也能變成藍牙喇叭接收器,或是透過 microSD 卡,播放 mp3/aac/ogg 或 midi 的音樂,讓 Ricky 的 HiFiBoy 計畫變得更加有趣。

    WB32-SFX 的 VS-1053B 晶片內建有 General MIDI 音源,可以發出一百多種樂器的聲音,只要能送進 MIDI Type0 的檔案或即時的 MIDI 訊號,就能演奏出美妙的樂音。

    我玩過好一陣子的數位音樂研究,其實非常熟悉 MIDI 的規格,二十年前曾經參與過 MIDI Wavetable Synthesizer 晶片開發,做過 MIDI Sequencer 播放器,也曾經研究 MIDI 音色製作,還參與編製過數千首 MIDI 卡拉OK的音樂。不過,這些只是好漢愛提的當年勇,我對這兩年剛出爐的藍牙無線版 BLE-MIDI 規格卻是一無所知,從未有過任何使用經驗。

    下載規格書:BLE-MIDI Specification @ Midi.Org

    為了 WB32-SFX 的 Realtime MIDI 音源應用範例,我們「ESP32 徹底研究小組」決定進行一個「無線藍牙 BLE-MIDI 收發器」的實作計畫,讓內建 WB32-SFX 模組的「HiFiBoy 可程式化喇叭」也可以接收無線 BLE-MIDI 控制器的指令,搖身一變成為一個厲害的數位樂器音源主機,可以用來即時演奏音樂。

    這確實是一個超級有趣的實作計畫,但似乎也是個難度相當高的實驗,畢竟 ESP32 的 BLE 範例都只是些小測試程式,似乎還沒有什麼應用範例可以參考。

    不管如何,再多難關總是要一關一關過的。

    我們先在 Amazon.jp 訂購了兩個 Korg 的 microKEY Air 藍牙 MIDI 鍵盤來做實驗。

    配對接上 iPad 的 GarageBand 或 Korg Gadget/Module App,就可以變成好玩的數位音樂錄音室。

    App 雖然好好玩,但我們的挑戰還沒開始呢!這個週末的實作計畫有三個:

    1. 研究 MIDI BLE 規格,弄清楚 microKEY Air 如何連上 iPad 的 GarageBand 進行彈奏。

    2. 寫一個模擬 MIDI BLE 控制器的程式,讓 WiFiBoy32 變成 microKEY Air,可以無線連接 iPad 上的 MIDI App 彈奏發出聲音。

    3. 寫一個能接收 MIDI BLE 控制器訊號的程式,讓 WB32-SFX 能接收 microKEY Air 的琴鍵 MIDI 訊號,彈奏出鋼琴樂音。

    第一個計畫很快有了初步的理解,我們下載了 MIDI.ORG 的 BLE-MIDI 規格書,只有區區十頁資料。仔細研究了幾個小時,發現重點就是兩個:

    1. BLE-MIDI 的設備,一定會有一個 MIDI Service, UUID: 03B80E5A-EDE8-4B33-A751-6CE34EC4C700

    2. 要獲取 MIDI Service 的訊號,需要透過 MIDI Data I/O Characteristic UUID: 7772E5DB-3868-4112-A1A9-F2669D106BF3

    3. BLE MIDI 資料格式:前面兩個 Timestamp bytes,後面接著 3 個 bytes 或更多的 MIDI Codes。

    這規格其實沒有太大的問題,比較麻煩的就是要先弄懂 BLE 的幾個規矩:

    1. BLE 透過 GATT 規範,由 Client 主機端向設備端的 Server 接收資料。沒看錯,是 Client 主機端,Server 設備端。也就是說 iPad 是 GATT Client,microKEY Air 是 GATT Server。

    2. GATT Server 要 Advertise 廣播適當的資料給大家看,讓 GATT Client 能找到 MIDI Service 與 Data I/O Characteristic。MIDI Service 需要提供 Write, Read, Notify 等三種服務。

    3. GATT Client 要 Scan 所有的 BLE 設備,選一個有 MIDI Service UUID 的來連接。再打開其 Data I/O Characteristic,建立 Notify 訊息 Callback。就可以從收到的 Notification 來解出 MIDI Codes。

    花了一些時間弄清楚了 BLE 與 MIDI Service 的協定流程,就可以開始寫程式了。

    我們以 ESP32 Arduino 寫了第一個實驗程式,WB32-GATT-Server,先裝在 WiFiBoy32 開發板上,透過 WiFiBoy32 上的六個按鍵,可以接上 iPad 的 GarageBand 演奏鋼琴。

    這個程式寫得非常順利,成果請看這個影片:

    這個程式只有三百多行,原始碼在此: wb32_gatt_server_ble_midi.ino

    <p>/*
     *  GATT-Server for BLE-MIDI -- WiFiBoy32 Demo Code for Arduino/ESP32
     *
     *  Oct 28, 2017 (derek@wifiboy.org)
     *  Modified from http://www.iotsharing.com/2017...
     */
    #pragma GCC diagnostic push
    #pragma GCC diagnostic warning "-fpermissive"
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include "freertos/FreeRTOS.h"
    #include "freertos/task.h"
    #include "freertos/event_groups.h"
    #include "esp_system.h"
    #include "esp_log.h"
    #include "nvs_flash.h"
    #include "bt.h"
    #include "bta_api.h"
    #include "esp_gap_ble_api.h"
    #include "esp_gatts_api.h"
    #include "esp_bt_defs.h"
    #include "esp_bt_main.h"
    #include "esp_bt_main.h"
    #include "sdkconfig.h"
    #include "wifiboy32.h"
    #pragma GCC diagnostic pop</p>
    <p>/* this function will be invoked to handle incomming events */
    static void gatts_profile_event_handler(esp_gatts_cb_event_t event, esp_gatt_if_t gatts_if, esp_ble_gatts_cb_param_t *param);</p>
    <p>#define TEST_DEVICE_NAME            "MiDiBoyBLE!"</p>
    <p>/* maximum value of a characteristic */
    #define GATTS_DEMO_CHAR_VAL_LEN_MAX 0xFF</p>
    <p>/* value range of a attribute (characteristic) */
    uint8_t attr_str[] = {0x00};
    esp_attr_value_t gatts_attr_val =
    {
        .attr_max_len = GATTS_DEMO_CHAR_VAL_LEN_MAX,
        .attr_len     = sizeof(attr_str),
        .attr_value   = attr_str,
    };</p>
    <p>/* service uuid */
    static uint8_t service_uuid128[32] = {
        0x00, 0xC7, 0xC4, 0x4E, 0xE3, 0x6C, 0x51, 0xA7, 0x33, 0x4B, 0xE8, 0xED, 0x5A, 0x0E, 0xB8, 0x03,
        0xF3, 0x6B, 0x10, 0x9D, 0x66, 0xF2, 0xA9, 0xA1, 0x12, 0x41, 0x68, 0x38, 0xDB, 0xE5, 0x72, 0x77
    };</p>
    <p>static uint8_t raw_adv_data[] = {
            0x02, 0x01, 0x06,
            0x11, 0x07, 0x00, 0xC7, 0xC4, 0x4E, 0xE3, 0x6C, 0x51, 0xA7, 0x33, 0x4B, 0xE8, 0xED, 0x5A, 0x0E, 0xB8, 0x03,
    };
    static uint8_t raw_scan_rsp_data[] = {
            0x0c, 0x09, 'M','i','D','i','B','o','y','B','L','E','!'
    };</p>
    <p>esp_ble_adv_params_t test_adv_params;</p>
    <p>#define PROFILE_ON_APP_ID 0
    #define CHAR_NUM 1</p>
    <p>struct gatts_characteristic_inst{
        esp_bt_uuid_t char_uuid;
        esp_bt_uuid_t descr_uuid;
        uint16_t char_handle;
        esp_gatt_perm_t perm;
        esp_gatt_char_prop_t property;
        uint16_t descr_handle;
    };</p>
    <p>struct gatts_profile_inst {
        esp_gatts_cb_t gatts_cb;
        uint16_t gatts_if;
        uint16_t app_id;
        uint16_t conn_id;
        uint16_t service_handle;
        esp_gatt_srvc_id_t service_id;
        struct gatts_characteristic_inst chars[CHAR_NUM];
    };</p>
    <p>/* One gatt-based profile one app_id and one gatts_if, this array will store the gatts_if returned by ESP_GATTS_REG_EVT */
    static struct gatts_profile_inst test_profile;</p>
    <p>/* this callback will handle process of advertising BLE info */
    static void gap_event_handler(esp_gap_ble_cb_event_t event, esp_ble_gap_cb_param_t *param)
    {
        switch (event) {
        case ESP_GAP_BLE_ADV_DATA_SET_COMPLETE_EVT:
            esp_ble_gap_start_advertising(&test_adv_params);
            break;
        case ESP_GAP_BLE_ADV_DATA_RAW_SET_COMPLETE_EVT:
            esp_ble_gap_start_advertising(&test_adv_params);
            break;
        case ESP_GAP_BLE_SCAN_RSP_DATA_RAW_SET_COMPLETE_EVT:
            esp_ble_gap_start_advertising(&test_adv_params);
            break;
        case ESP_GAP_BLE_ADV_START_COMPLETE_EVT:
            //advertising start complete event to indicate advertising start successfully or failed
            if (param->adv_start_cmpl.status != ESP_BT_STATUS_SUCCESS) Serial.println("Advertising start failed\n");
            break;
        case ESP_GAP_BLE_ADV_STOP_COMPLETE_EVT:
            if (param->adv_stop_cmpl.status != ESP_BT_STATUS_SUCCESS) Serial.println("Advertising stop failed\n");
            else Serial.println("Stop adv successfully\n");
            break;
        default:
            break;
        }
    }</p>
    <p>/* this callback handle BLE profile such as registering services and characteristics, send response to central device */
    static void gatts_profile_event_handler(esp_gatts_cb_event_t event, esp_gatt_if_t gatts_if, esp_ble_gatts_cb_param_t *param) {
        switch (event) {
        /* create service event */
        case ESP_GATTS_REG_EVT:
            printf("REGISTER_APP_EVT, status %d, app_id %d\n", param->reg.status, param->reg.app_id);
            test_profile.service_id.is_primary = true;
            test_profile.service_id.id.inst_id = 0x00;
            test_profile.service_id.id.uuid.len = ESP_UUID_LEN_128;
            for(int i=0; i<16; i++) test_profile.service_id.id.uuid.uuid.uuid128[i] = service_uuid128[i];
            esp_ble_gap_set_device_name(TEST_DEVICE_NAME);
            esp_ble_gap_config_adv_data_raw(raw_adv_data, sizeof(raw_adv_data));
            esp_ble_gap_config_scan_rsp_data_raw(raw_scan_rsp_data, sizeof(raw_scan_rsp_data));
            esp_ble_gatts_create_service(gatts_if, &test_profile.service_id, 4);
            break;
        /* when central device request info from this device, this event will be invoked and respond */
        case ESP_GATTS_READ_EVT: {
            printf("ESP_GATTS_READ_EVT, conn_id %d, trans_id %d, handle %d\n", param->read.conn_id, param->read.trans_id, param->read.handle);
            esp_gatt_rsp_t rsp;
            memset(&rsp, 0, sizeof(esp_gatt_rsp_t));
            rsp.attr_value.handle = param->read.handle;
            rsp.attr_value.len = 1;
            rsp.attr_value.value[0] = 0;
            esp_ble_gatts_send_response(gatts_if, param->read.conn_id, param->read.trans_id, ESP_GATT_OK, &rsp);
            break;
        }
        /* when central device send data to this device, this event will be invoked */
        case ESP_GATTS_WRITE_EVT: {
            printf("ESP_GATTS_WRITE_EVT, conn_id %d, trans_id %d, handle %d\n", param->write.conn_id, param->write.trans_id, param->write.handle);
            printf("value len %d, value %08x\n", param->write.len, *(uint8_t *)param->write.value);
            break;
        }
        /* start service and add characterstic event */
        case ESP_GATTS_CREATE_EVT:
            printf("status %d,  service_handle %d\n", param->create.status, param->create.service_handle);
            test_profile.service_handle = param->create.service_handle; 
            esp_ble_gatts_add_char(test_profile.service_handle, &test_profile.chars[0].char_uuid,
                                   ESP_GATT_PERM_READ | ESP_GATT_PERM_WRITE,
                                   ESP_GATT_CHAR_PROP_BIT_READ | ESP_GATT_CHAR_PROP_BIT_WRITE_NR | ESP_GATT_CHAR_PROP_BIT_NOTIFY,
                                   &gatts_attr_val, NULL);
            esp_ble_gatts_start_service(test_profile.service_handle);
            break;
        case ESP_GATTS_ADD_CHAR_EVT: {
            printf("ADD_CHAR_EVT, status %d,  attr_handle %d, service_handle %d (%x)\n",
                    param->add_char.status, param->add_char.attr_handle, param->add_char.service_handle, param->add_char.char_uuid.uuid.uuid128[0]);
            if(param->add_char.char_uuid.uuid.uuid128[0] == 0xf3){
                test_profile.chars[0].char_handle = param->add_char.attr_handle;
            }
            break;
        }
        case ESP_GATTS_ADD_CHAR_DESCR_EVT:
            printf("ESP_GATTS_ADD_CHAR_DESCR_EVT, status %d, attr_handle %d, service_handle %d\n",
                     param->add_char.status, param->add_char.attr_handle, param->add_char.service_handle);
            break;
        case ESP_GATTS_DISCONNECT_EVT:
            esp_ble_gap_start_advertising(&test_adv_params);
            wb32_fillRect(20,120,120,15,0);
            break;
        case ESP_GATTS_CONNECT_EVT: {
            printf("ESP_GATTS_CONNECT_EVT\n");
            esp_ble_conn_update_params_t conn_params = {0};
            memcpy(conn_params.bda, param->connect.remote_bda, sizeof(esp_bd_addr_t));
            /* For the IOS system, please reference the apple official documents about the ble connection parameters restrictions. */
            conn_params.latency = 0;
            conn_params.max_int = 0x30;
            conn_params.min_int = 0x20;
            conn_params.timeout = 500;
            printf("ESP_GATTS_CONNECT_EVT, conn_id %d, remote %02x:%02x:%02x:%02x:%02x:%02x:, is_conn %d\n",
                     param->connect.conn_id,
                     param->connect.remote_bda[0], param->connect.remote_bda[1], param->connect.remote_bda[2],
                     param->connect.remote_bda[3], param->connect.remote_bda[4], param->connect.remote_bda[5],
                     param->connect.is_connected);
            test_profile.conn_id = param->connect.conn_id;
            //start sent the update connection parameters to the peer device.
            esp_ble_gap_update_conn_params(&conn_params);
            wb32_drawString("Connected!", 20, 120, 1, 2);
            break;
        }
        default:
            break;
        }
    }</p>
    <p>static void gatts_event_handler(esp_gatts_cb_event_t event, esp_gatt_if_t gatts_if, esp_ble_gatts_cb_param_t *param)
    {
        /* If event is register event, store the gatts_if for each profile */
        if (event == ESP_GATTS_REG_EVT) {
            if (param->reg.status == ESP_GATT_OK) test_profile.gatts_if = gatts_if;
            else {
                printf("Reg app failed, app_id %04x, status %d\n", param->reg.app_id, param->reg.status);
                return;
            }
        }
        /* here call each profile's callback */
        if (gatts_if == ESP_GATT_IF_NONE || gatts_if == test_profile.gatts_if)
            if (test_profile.gatts_cb) test_profile.gatts_cb(event, gatts_if, param);
    }</p>
    <p>void setup()
    {
        wb32_init();
        wb32_setTextColor(wbYELLOW, wbYELLOW);
        wb32_drawString("MiDiBoy on WiFiBoy", 20, 20, 1, 3);
        wb32_setTextColor(wbWHITE, wbWHITE);    
        wb32_drawString("BLE-MIDI Test", 20, 70, 1, 2);
        wb32_setTextColor(wbGREEN, wbGREEN); 
        wb32_drawString("(C)2017 WiFiBoy.Org & WiFiBoy.Club", 20, 300, 2, 1);
        for(int i=0; i<7; i++) wb32_fillRect(i*31+13, 160, 28, 120, 0xffff);
        for(int i=0; i<2; i++) wb32_fillRect(i*31+31, 160, 23, 75, 0);
        for(int i=3; i<6; i++) wb32_fillRect(i*31+31, 160, 23, 75, 0);
        Serial.begin(115200);
        test_adv_params.adv_int_min        = 0x20;
        test_adv_params.adv_int_max        = 0x30;
        test_adv_params.adv_type           = ADV_TYPE_IND;
        test_adv_params.own_addr_type      = BLE_ADDR_TYPE_PUBLIC;
        test_adv_params.channel_map        = ADV_CHNL_ALL;
        test_adv_params.adv_filter_policy  = ADV_FILTER_ALLOW_SCAN_ANY_CON_ANY;
        test_profile.gatts_cb = gatts_profile_event_handler;
        test_profile.gatts_if = ESP_GATT_IF_NONE; /* Not get the gatt_if, so initial is ESP_GATT_IF_NONE */
        test_profile.chars[0].char_uuid.len = ESP_UUID_LEN_128;
        for(int i=0; i<16; i++) test_profile.chars[0].char_uuid.uuid.uuid128[i] = service_uuid128[i+16];
        test_profile.chars[0].perm = ESP_GATT_PERM_READ | ESP_GATT_PERM_WRITE_ENCRYPTED;
        test_profile.chars[0].property = ESP_GATT_CHAR_PROP_BIT_READ | ESP_GATT_CHAR_PROP_BIT_WRITE_NR | ESP_GATT_CHAR_PROP_BIT_NOTIFY;
        
        btStart();
        esp_bluedroid_init();
        esp_bluedroid_enable();
        esp_ble_gatts_register_callback(gatts_event_handler);
        esp_ble_gap_register_callback(gap_event_handler);
        esp_ble_gatts_app_register(0);
        
        pinMode(33,INPUT); pinMode(17,INPUT); pinMode(27,INPUT);
        pinMode(32,INPUT); pinMode(34,INPUT); pinMode(35,INPUT);
    }</p>
    <p>int lastkey1=0, lastkey2=0, lastkey3=0, lastkey4=0, lastkey5=0, lastkey6=0;</p>
    <p>void loop()
    {
        char mididata1[]={0x82, 0x84, 0x90, 0x30, 0x50};
        char mididata2[]={0x82, 0x84, 0x80, 0x30, 0x50};
      
        if ((digitalRead(33)==0)&&(lastkey1!=1)) {
            mididata1[3]=0x30;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata1, false);
            lastkey1=1;
            wb32_fillRect(0*31+20, 250, 14, 15, wbYELLOW);
        }
        if ((digitalRead(33)==1)&&(lastkey1==1)) {
            mididata2[3]=0x30;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata2, false);
            lastkey1=0;
            wb32_fillRect(0*31+20, 250, 14, 15, wbWHITE);
        }
        if ((digitalRead(17)==0)&&(lastkey2!=2)) {
            mididata1[3]=0x32;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata1, false);
            lastkey2=2;
            wb32_fillRect(1*31+20, 250, 14, 15, wbGREEN);
        }
        if ((digitalRead(17)==1)&&(lastkey2==2)) {
            mididata2[3]=0x32;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata2, false);
            lastkey2=0;
            wb32_fillRect(1*31+20, 250, 14, 15, wbWHITE);
        }
        if ((digitalRead(27)==0)&&(lastkey3!=3)) {
            mididata1[3]=0x34;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata1, false);
            lastkey3=3;
            wb32_fillRect(2*31+20, 250, 14, 15, wbBLUE);
        }
        if ((digitalRead(27)==1)&&(lastkey3==3)) {
            mididata2[3]=0x34;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata2, false);
            lastkey3=0;
            wb32_fillRect(2*31+20, 250, 14, 15, wbWHITE);
        }
        if ((digitalRead(32)==0)&&(lastkey4!=4)) {
            mididata1[3]=0x35;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata1, false);
            lastkey4=4;
            wb32_fillRect(3*31+20, 250, 14, 15, wbRED);
        }
        if ((digitalRead(32)==1)&&(lastkey4==4)) {
            mididata2[3]=0x35;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata2, false);
            lastkey4=0;
            wb32_fillRect(3*31+20, 250, 14, 15, wbWHITE);
        }
        if ((digitalRead(34)==0)&&(lastkey5!=5)) {
            mididata1[3]=0x37;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata1, false);
            lastkey5=5;
            wb32_fillRect(4*31+20, 250, 14, 15, wbBLUE);
        }
        if ((digitalRead(34)==1)&&(lastkey5==5)) {
            mididata2[3]=0x37;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata2, false);
            lastkey5=0;
            wb32_fillRect(4*31+20, 250, 14, 15, wbWHITE);
        }
        if ((digitalRead(35)==0)&&(lastkey6!=6)) {
            mididata1[3]=0x39;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata1, false);
            lastkey6=6;
            wb32_fillRect(5*31+20, 250, 14, 15, wbYELLOW);
        }
        if ((digitalRead(35)==1)&&(lastkey6==6)) {
            mididata2[3]=0x39;
            esp_ble_gatts_send_indicate(test_profile.gatts_if, test_profile.conn_id, 
                test_profile.chars[0].char_handle, 5, mididata2, false);
            lastkey6=0;
            wb32_fillRect(5*31+20, 250, 14, 15, wbWHITE);
        }
        delay(10);
    }</p>
    

    第二個實驗程式,是要讓 WB32-SFX 能接收 microKEY Air 的琴鍵 MIDI 訊號。

    這個程式遇到比較多的麻煩,沒有興趣深究的不需要仔細看,摘要如下:

    1. 參考 ESP-IDF 範例寫了基本的 BLE GATT-Client 程式,可以接收先前 WiFiBoy32 的 GATT-Server 按鍵 MIDI Codes,但收不到 microKEY Air 的按鍵 MIDI Codes。

    2. 花了些時間才發現是 Notify 的設定,需要對 Descriptor 寫入一個 0x01 的數值,必須正確設定 GATT Authentication Type,要選用 NO_MITM 的認證設定。

    3. ESP32 的 BLE 功能是要開 Bluetooth Dual Mode 的,整個模組耗電流實測高達 160mA(USB 5V端),根本就不太 Low Energy 啊!ESP32 模組甚至還會發出微微溫度,顯然還需要繼續努力,Espressif 團隊說省電模式正在開發中,現在的 3.0 版 ESP-IDF 似乎還沒有太大改進。我試著將 ESP32 主 CPU 速度從 240Mhz 降為 80Mhz,整體耗電流可以降至 130mA 左右,這才使得 WB32-SFX 電力輸出有點虛弱的工程樣板,可以正常運作起來。ESP32 的 WiFi+BLE 無線通訊模組的瞬間電流需求相當高,據說會高達 300~400mA,WB32 開發板需要特別加強瞬間供電的能力。

    總之,花了幾個小時,第二個程式終於可以接收 microKEY Air 的 MIDI 訊號,讓 WB32-SFX 發出令人感動的鋼琴聲了!

    請看影片:(稍後上傳)

    原始程式在這裡(稍後上傳),若有興趣研究細節,請看程式裡的註解,或是在本文後面留言討論。

    做這個範例的過程雖然辛苦,但實驗的結果一路都非常好玩。

    這次的實作成果會在下週末的 Maker Faire Taipei 2017,11/3~11/5 在光華商場旁的華山園區展出。我們 WiFiBoy.Org 有兩個攤位,攤位名稱「HiFiBoy DIy Speaker」,戶外是在: 室內則是:。歡迎蒞臨指導!

    (Maker Faire Taipei 展覽期間有這次實驗用的 WiFiBoy32 的上市特惠方案,現場數量有限,只有 100 套,敬請支持!)


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