2021暑假练平台3——基于ESP32-S2-Mini-1模块的音频处理平台制作两用收音机by yk

内容介绍

平台介绍

本次使用的音频处理平台，是基于乐鑫官方模块ESP32-S2-Mini-1制作的。该模块由一颗ESP32S2的处理器，和一颗可以运行在80M的QPI上的Flash以及一些外围电路组成。ESP32S2是一颗单核的Xtensa32的处理器，能运行在240MHz的主频上。官方提供了esp-idf和Arduino等开发框架，本次我在这使用esp-idf作为开发框架开发。

任务需求

实现网络收音机和FM收音机的功能

可以通过WiFi接收网络上的电台，也可以通过FM模块接收空中的电台，并可以通过案件进行切换、选台
在OLED显示屏上显示网络电台的IP地址、节目名称等相关信息或FM信号的频段
系统能够自动校时，开机后自动调节到准确的时间（年月日时分秒）

设计思路

FkLOdNrYoP7W5so12AbsK9hpoWkc

使用四个按键来调整一些标志位，GUI中通过标志位来决定显示什么界面。

具体实现

WiFi配置部分

WiFi配置部分主要使用了乐鑫提供的例程smartconfig。示例工程在esp-idf\examples\wifi\smart_config下，使用手机APP：EspTouch进行WiFi账号和密码的配置。改动不大，增加了一个全局标志位isConnect，在WiFi连接后置true。

校时部分

校时部分主要使用了乐鑫在CSDN上的文章，当然乐鑫也提供了例程，在esp-idf\examples\protocols\sntp下。CSDN上的文章中更为简略。同样的，我也添加了一个全局标志位isTimeCorrect。以下是我的代码

bool isTimeCorrect = false;

static const char *TAG = "sntp";

static void esp_initialize_sntp(void) {
   ESP_LOGI(TAG, "Initializing SNTP");
   sntp_setoperatingmode(SNTP_OPMODE_POLL);
   sntp_setservername(0, "ntp.tuna.tsinghua.edu.cn");
   sntp_setservername(1, "ntp1.aliyun.com");
   sntp_setservername(2, "210.72.145.44");
   sntp_init();
}

void esp_wait_sntp_sync(void) {
   char strftime_buf[64];
   esp_initialize_sntp();

   // wait for time to be set
   time_t now = 0;
   int retry = 0;
   struct tm timeinfo = {0};

   while (timeinfo.tm_year < (2019 - 1900)) {
       ESP_LOGD(TAG, "Waiting for system time to be set... (%d)", ++retry);
       vTaskDelay(100 / portTICK_PERIOD_MS);
       time(&now);
       localtime_r(&now, &timeinfo);
  }

   // set timezone to China Standard Time
   setenv("TZ", "CST-8", 1);
   tzset();

   strftime(strftime_buf, sizeof(strftime_buf), "%c", &timeinfo);
   ESP_LOGI(TAG, "The current date/time in Shanghai is: %s", strftime_buf);
   isTimeCorrect = true;

   sntp_stop();
}

在线音频流播放部分

在线音频流使用了蜻蜓FM提供的API。此部分主要参考了乐鑫esp-adf库的示例程序esp-adf\examples\player\pipeline_living_stream和esp-adf\examples\player\pipeline_play_mp3_with_dac_or_pwm。删去了解码芯片初始化、i2s初始化和WiFi初始化等部分，并将pipeline_living_stream中的i2s输出改为了pwm输出。参考示例程序增加了换台的部分。

void MY_AUDIO_Init() {
   esp_log_level_set("*", ESP_LOG_INFO);
   esp_log_level_set(TAG, ESP_LOG_DEBUG);

//   ESP_LOGI(TAG, "[ 1 ] Start audio codec chip");
//   audio_board_handle_t board_handle = audio_board_init();
//   audio_hal_ctrl_codec(board_handle->audio_hal, AUDIO_HAL_CODEC_MODE_DECODE, AUDIO_HAL_CTRL_START);

   ESP_LOGI(TAG, "[2.0] Create audio pipeline for playback");
   audio_pipeline_cfg_t pipeline_cfg = DEFAULT_AUDIO_PIPELINE_CONFIG();
   pipeline = audio_pipeline_init(&pipeline_cfg);

   ESP_LOGI(TAG, "[2.1] Create http stream to read data");
   http_stream_cfg_t http_cfg = HTTP_STREAM_CFG_DEFAULT();
   http_cfg.event_handle = _http_stream_event_handle;
   http_cfg.type = AUDIO_STREAM_READER;
   http_cfg.enable_playlist_parser = true;
   http_stream_reader = http_stream_init(&http_cfg);

   ESP_LOGI(TAG, "[2.2] Create pwm stream to write data to codec chip");
   pwm_stream_cfg_t pwm_cfg = PWM_STREAM_CFG_DEFAULT();
   pwm_cfg.pwm_config.gpio_num_left = AUDIO_Pin;
   pwm_cfg.pwm_config.gpio_num_right = AUDIO_Pin + 1;
   output_stream_writer = pwm_stream_init(&pwm_cfg);

   ESP_LOGI(TAG, "[2.3] Create aac decoder to decode aac file");
   aac_decoder_cfg_t aac_cfg = {
          .out_rb_size=(2 * 1024),
          .task_stack=(4 * 1024),
          .task_core=(0),
          .task_prio=(5),
          .stack_in_ext=1,
  };
   aac_decoder = aac_decoder_init(&aac_cfg);

   ESP_LOGI(TAG, "[2.4] Register all elements to audio pipeline");
   audio_pipeline_register(pipeline, http_stream_reader, "http");
   audio_pipeline_register(pipeline, aac_decoder, "aac");
   audio_pipeline_register(pipeline, output_stream_writer, "pwm");

   ESP_LOGI(TAG, "[2.5] Link it together http_stream-->aac_decoder-->pwm_stream");
   const char *link_tag[3] = {"http", "aac", "pwm"};
   audio_pipeline_link(pipeline, &link_tag[0], 3);

   ESP_LOGI(TAG, "[2.6] Set up uri (http as http_stream, aac as aac decoder, and default output is pwm)");
   char url[100];
   sprintf(url, "http://open.ls.qingting.fm/live/%d/64k.m3u8?format=aac", stationIDList[stationID]);
   audio_element_set_uri(http_stream_reader, url);

//   ESP_LOGI(TAG, "[ 3 ] Start and wait for Wi-Fi network");
//   esp_periph_config_t periph_cfg = DEFAULT_ESP_PERIPH_SET_CONFIG();
//   set = esp_periph_set_init(&periph_cfg);
//   periph_wifi_cfg_t wifi_cfg = {
//           .ssid = (const char *) wifi_config.sta.ssid,
//           .password = (const char *) wifi_config.sta.password,
//   };
//   esp_periph_handle_t wifi_handle = periph_wifi_init(&wifi_cfg);
//   esp_periph_start(set, wifi_handle);
//   periph_wifi_wait_for_connected(wifi_handle, portMAX_DELAY);

   ESP_LOGI(TAG, "[ 4 ] Set up event listener");
   audio_event_iface_cfg_t evt_cfg = AUDIO_EVENT_IFACE_DEFAULT_CFG();
   evt = audio_event_iface_init(&evt_cfg);

   ESP_LOGI(TAG, "[4.1] Listening event from all elements of pipeline");
   audio_pipeline_set_listener(pipeline, evt);

   ESP_LOGI(TAG, "[4.2] Listening event from peripherals");
//   audio_event_iface_set_listener(esp_periph_set_get_event_iface(set), evt);

   ESP_LOGI(TAG, "[ 5 ] Start audio_pipeline");
   audio_pipeline_run(pipeline);
}

void Audio_Play() {
   while (1) {
       audio_event_iface_msg_t msg;
       esp_err_t ret = audio_event_iface_listen(evt, &msg, portMAX_DELAY);
       if (ret != ESP_OK) {
           ESP_LOGE(TAG, "[ * ] Event interface error : %d", ret);
           continue;
      }

       if (msg.source_type == AUDIO_ELEMENT_TYPE_ELEMENT &&
           msg.source == (void *) aac_decoder &&
           msg.cmd == AEL_MSG_CMD_REPORT_MUSIC_INFO) {
           audio_element_info_t music_info = {0};
           audio_element_getinfo(aac_decoder, &music_info);

           ESP_LOGI(TAG, "[ * ] Receive music info from aac decoder, sample_rates=%d, bits=%d, ch=%d",
                    music_info.sample_rates, music_info.bits, music_info.channels);

           audio_element_setinfo(output_stream_writer, &music_info);
           pwm_stream_set_clk(output_stream_writer, music_info.sample_rates, music_info.bits, music_info.channels);
           continue;
      }

       /* restart stream when the first pipeline element (http_stream_reader in this case) receives stop event (caused by reading errors) */
       if (msg.source_type == AUDIO_ELEMENT_TYPE_ELEMENT && msg.source == (void *) http_stream_reader
           && msg.cmd == AEL_MSG_CMD_REPORT_STATUS && (int) msg.data == AEL_STATUS_ERROR_OPEN) {
           ESP_LOGW(TAG, "[ * ] Restart stream");
           audio_pipeline_stop(pipeline);
           audio_pipeline_wait_for_stop(pipeline);
           audio_element_reset_state(aac_decoder);
           audio_element_reset_state(output_stream_writer);
           audio_pipeline_reset_ringbuffer(pipeline);
           audio_pipeline_reset_items_state(pipeline);
           audio_pipeline_run(pipeline);
           continue;
      }
  }
}

void Audio_SelectStation(uint16_t new_stationID) {
   char url[100];
   sprintf(url, "http://open.ls.qingting.fm/live/%d/64k.m3u8?format=aac", stationIDList[new_stationID]);
   audio_pipeline_stop(pipeline);
   audio_pipeline_wait_for_stop(pipeline);
   audio_element_reset_state(aac_decoder);
   audio_element_reset_state(output_stream_writer);
   audio_pipeline_reset_ringbuffer(pipeline);
   audio_pipeline_reset_items_state(pipeline);
   audio_element_set_uri(http_stream_reader, url);
   audio_pipeline_run(pipeline);
}

GUI部分

GUI部分我新建了一个线程，根据各个标志位来判断模式，显示各类信息

void GUI_Init() {
   xTaskCreate(GUI_Task, "GUI_Task", 4096, NULL, 3, NULL);
}
void GUI_Task() {
   while (1) {
       if (!isConnect) {
           OLED_ShowNotConnect();
           lastState = 0;
      } else {
           if (!isTimeCorrect) {
               OLED_ShowTimeCalibrating();
               lastState = 1;
          } else {
               OLED_ShowTime();
               if (isFM) {
                   OLED_ShowFM();
                   lastState = 2;
              } else {
                   OLED_ShowInternetFM();
                   lastState = 3;
              }
          }
      }
       vTaskDelay(100 / portTICK_RATE_MS);
  }
}

显示提示

WiFi未连接时和连接后的校时时，显示一串字符串，表明状态

void OLED_ShowNotConnect() {
   if (lastState != 0) {
       OLED_Clear();
       OLED_ShowString(0, 0, (uint8_t *) "Wifi is not connected. Please Connect Wifi with EspTouch.", 16);
  }
}

void OLED_ShowTimeCalibrating() {
   if (lastState != 1) {
       OLED_Clear();
       OLED_ShowString(0, 0, (uint8_t *) "Wifi is connected. Trying to calibrate time...", 16);
  }
}

显示FM界面

显示FM的频段和信号强度（rssi）

uint32_t freq_temp = -1;
void OLED_ShowFM() {
   static uint8_t rssi_temp = -1;
   char ch[30];
   RDA_ReadAllInfo();
   if (lastState != 2) {
       OLED_Clear();
       SetMuxFM();
       OLED_ShowString(0, 0, (uint8_t *) "FM", 16);

       sprintf(ch, "freq:%6d", RDA5807.freq);
       OLED_ShowString(0, 2, (uint8_t *) ch, 16);
       freq_temp = RDA5807.freq;

       sprintf(ch, "rssi: %2d/64", RDA5807.radioInfo.rssi + 1);
       OLED_ShowString(0, 4, (uint8_t *) ch, 16);
       rssi_temp = RDA5807.radioInfo.rssi;

       OLED_ShowString(0, 6, (uint8_t *) "SW Pre Nex Mute", 16);
  } else {
       if (freq_temp != RDA5807.freq) {
           sprintf(ch, "freq:%6d", freq_temp);
           OLED_ShowString(0, 2, (uint8_t *) ch, 16);
           RDA_SetFrequency(freq_temp);
      }
       if (rssi_temp != RDA5807.radioInfo.rssi) {
           sprintf(ch, "rssi: %2d/64", RDA5807.radioInfo.rssi + 1);
           OLED_ShowString(0, 4, (uint8_t *) ch, 16);
           rssi_temp = RDA5807.radioInfo.rssi;
      }
  }
}

显示网络电台。

显示本次使用的电台蜻蜓FM的IP和当前节目名称。根据蜻蜓FM的开放平台的品牌露出规范，添加相应的字符

void OLED_ShowInternetFM() {
   static uint8_t stationID_temp = -1;
   char ch[30];
   if (lastState != 3) {
       OLED_Clear();
       SetMuxESP();
       OLED_ShowString(0, 0, (uint8_t *) "OL", 16);

       OLED_ShowString(0, 2, (uint8_t *) "IP:115.231.142.5", 16);

       sprintf(ch, "FM%4d", ConvStaIDToName(stationIDList[stationID]));
       OLED_ShowString(0, 4, (uint8_t *) ch, 16);
       stationID_temp = stationID;

       OLED_ShowQingtingLogo(6 * 8, 4);

       OLED_ShowString(0, 6, (uint8_t *) "SW Pre Nex Mute", 16);
  } else {
       if (stationID_temp != stationID) {
           Audio_SelectStation(stationID);
           sprintf(ch, "FM%4d", ConvStaIDToName(stationIDList[stationID]));
           OLED_ShowString(0, 4, (uint8_t *) ch, 16);
           stationID_temp = stationID;
      }
  }
}
uint16_t ConvStaIDToName(uint16_t _stationID) {
   switch (_stationID) {
       case 4522:            return 930;      //FM93交通之声
       case 4518:            return 880;      //浙江之声
       case 1133:            return 918;      //杭州交通91.8电台
       case 1163:            return 1054;     //西湖之声
       case 4521:            return 996;      //浙江FM99.6
       case 1135:            return 922;      //嘉兴交通广播
       case 4866:            return 968;      //浙江音乐调频
       case 4523:            return 1070;     //浙江城市之声
       default:              return -1;
  }
}

void OLED_ShowQingtingLogo(uint8_t x, uint8_t y) {
   const uint8_t logo[][16] = {
          {0x00, 0x08, 0x08, 0x28, 0xC8, 0x08, 0x08, 0xFF, 0x08, 0x08, 0x88, 0x68, 0x08, 0x08, 0x00, 0x00},
          {0x21, 0x21, 0x11, 0x11, 0x09, 0x05, 0x03, 0xFF, 0x03, 0x05, 0x09, 0x11, 0x11, 0x21, 0x21, 0x00},/*"来",0*/

          {0x00, 0x00, 0x00, 0xF8, 0x88, 0x8C, 0x8A, 0x89, 0x88, 0x88, 0x88, 0xF8, 0x00, 0x00, 0x00, 0x00},
          {0x00, 0x00, 0x00, 0xFF, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0x44, 0xFF, 0x00, 0x00, 0x00, 0x00},/*"自",1*/

          {0x00, 0xF8, 0x08, 0xFF, 0x08, 0xF8, 0x44, 0x54, 0x54, 0x54, 0x7F, 0x54, 0x54, 0x54, 0x44, 0x00},
          {0x20, 0x63, 0x21, 0x1F, 0x11, 0x39, 0x00, 0xFF, 0x15, 0x15, 0x15, 0x55, 0x95, 0x7F, 0x00, 0x00},/*"蜻",2*/

          {0xF8, 0x08, 0xFF, 0x08, 0xF8, 0x00, 0x84, 0xE4, 0x9C, 0x00, 0x44, 0x44, 0xFC, 0x42, 0x42, 0x00},
          {0x23, 0x61, 0x3F, 0x11, 0xB9, 0x40, 0x26, 0x18, 0x27, 0x40, 0x48, 0x48, 0x4F, 0x48, 0x48, 0x00},/*"蜓",3*/
  };

   for (uint8_t j = 0; j < 2; j++) {
       OLED_Set_Pos(x + j * 16, y);
       for (uint8_t i = 0; i < 16; i++) {
           OLED_WR_DATA(logo[2 * j][i]);
      }
       OLED_Set_Pos(x + j * 16, y + 1);
       for (uint8_t i = 0; i < 16; i++) {
           OLED_WR_DATA(logo[2 * j + 1][i]);
      }
  }
//   OLED_ShowChar(x + 2 * 16, y, ' ', 16);
   for (uint8_t j = 2; j < 4; j++) {
       OLED_Set_Pos(x + j * 16, y);
       for (uint8_t i = 0; i < 16; i++) {
           OLED_WR_DATA(logo[2 * j][i]);
      }
       OLED_Set_Pos(x + j * 16, y + 1);
       for (uint8_t i = 0; i < 16; i++) {
           OLED_WR_DATA(logo[2 * j + 1][i]);
      }
  }
   OLED_ShowChar(x + 4 * 16, y, 'F', 16);
   OLED_ShowChar(x + 4 * 16 + 8, y, 'M', 16);
}

显示时间

由于空间限制，在这里实现循环显示约5秒的时间2秒的日期。

void OLED_ShowTime() {
   static uint8_t i = 0;
   char ch[30];
   time_t now = 0;
   struct tm timeinfo = {0};
   i++;
   time(&now);
   localtime_r(&now, &timeinfo);

   if (i > 50) {
       sprintf(ch, "%2dy%2dm%2dd",
               timeinfo.tm_year % 100, timeinfo.tm_mon + 1, timeinfo.tm_mday);
       if (i == 70) {
           i = 0;
      }
  } else {
       sprintf(ch, "%2d:%2d:%2d ",
               timeinfo.tm_hour, timeinfo.tm_min, timeinfo.tm_sec);
  }

   OLED_ShowString(56, 0, (uint8_t *) ch, 16);
}

按键部分

按键初始化为输入并附加外部中断回调

static void gpio_isr_handler(void *arg) {
   uint32_t gpio_num = (uint32_t) arg;
   switch (gpio_num) {
       case Key1_Pin:
           isFM = !isFM;
           break;
       case Key2_Pin:
           if (isFM) {
               freq_temp -= RDA5807.channelSpacing;
          } else {
               if (stationID == 0) {
                   stationID = 7;
              } else {
                   stationID--;
              }
          }
           break;
       case Key3_Pin:
           if (isFM) {
               freq_temp += RDA5807.channelSpacing;
          } else {
               if (stationID == 7) {
                   stationID = 0;
              } else {
                   stationID++;
              }
          }
           break;
       case Key4_Pin:
           ToggleSpeaker();
           break;
       default:
           break;
  }
}

结果展示

FjU282P0jLM2b5xxHiDchWhenCj4 Fqkr1nhYVdGiJLmhXEB6xp2Ie97X

心得体会

这次活动让我学习了解了和传统嵌入式开发略有不同的开发方式。乐鑫提供了基于cmake的开发环境取代了传统的自己写makefile或是使用keil等软件编译。当然，使用Clion开发的我也很顺滑的过渡到了ESP32的开发。这次活动让我也熟悉了高性价比的ESP32，或许以后会替代价格不太合理的STM32作为我的主力MCU吧

完整项目地址：kaidegit/eetree-esp32-radio (github.com)