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# Over-the-air 更新演示应用程序
<a name="ota-demo"></a>

FreeRTOS 包含一个演示应用程序，用于演示 (OTA) 库 over-the-air的功能。OTA 演示应用程序位于 `freertos/demos/ota/ota_demo_core_mqtt/ota_demo_core_mqtt.c` 或 `freertos/demos/ota/ota_demo_core_http/ota_demo_core_http.c` 文件中。

OTA 演示应用程序执行以下操作：

1. 初始化 FreeRTOS 网络堆栈和 MQTT 缓冲池。

1. 使用 `vRunOTAUpdateDemo()` 创建任务来执行 OTA 库。

1. 使用 `_establishMqttConnection()` 创建 MQTT 客户端。

1. 使用连接到 Amazon IoT MQTT 代理`IotMqtt_Connect()`并注册 MQTT 断开连接回调:。`prvNetworkDisconnectCallback`

1. 调用 `OTA_AgentInit()` 创建 OTA 任务，并注册在 OTA 任务完成时使用的回调。

1. 使用 `xOTAConnectionCtx.pvControlClient = _mqttConnection;` 重用 MQTT 连接。

1. 如果 MQTT 断开连接，应用程序将暂停 OTA 代理，尝试使用带有抖动的指数延迟重新连接，然后恢复 OTA 代理。

在使用 OTA 更新之前，请完成 [FreeRTOS 更新 Over-the-Air](freertos-ota-dev.md) 中的所有先决条件

在完成 OTA 更新的设置后，在支持 OTA 功能的平台上下载、构建、刷写并运行 FreeRTOS OTA 演示。设备特定的演示说明可用于以下取得 FreeRTOS 认证的设备：
+ [德州仪器 CC3220 SF-LAUNCHXL](download-ota-ti.md)
+ [微芯片好奇号 PIC32 MZEF](download-ota-mchip.md)
+ [Espressif ESP32](download-ota-esp.md)
+ [在瑞萨 N 上下载、构建、刷新并运行 FreeRTOS OTA 演示 RX65](download-rx65n-ota.md)

在设备上构建、刷新和运行 OTA 演示应用程序后，您可以使用 Amazon IoT 控制台或创建 OTA 更新任务。 Amazon CLI 在您创建 OTA 更新任务之后，连接到终端仿真器以查看 OTA 更新的进度。记下此过程中生成的任何错误。

成功 OTA 更新作业会显示类似以下内容的输出。为简便起见，在本示例中，我们删除了列表中的一些行。

```
    249 21207 [iot_thread] [ota_demo_core_mqtt.c:1850] [INFO] [MQTT]  Received: 0   Queued: 0   Processed: 0   Dropped: 0
    250 21247 [MQTT Agent Task] [core_mqtt.c:886] [INFO] [MQTT] Packet received. ReceivedBytes=601.
    251 21247 [MQTT Agent Task] [core_mqtt.c:1045] [INFO] [MQTT] De-serialized incoming PUBLISH packet: DeserializerResult=MQTTSuccess.
    252 21248 [MQTT Agent Task] [core_mqtt.c:1058] [INFO] [MQTT] State record updated. New state=MQTTPubAckSend.
    253 21249 [MQTT Agent Task] [ota_demo_core_mqtt.c:976] [INFO] [MQTT] Received job message callback, size 548.
    254 21252 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[execution.jobId: AFR_OTA-9702f1a3-b747-4c3e-a0eb-a3b0cf83ddbb]
    255 21253 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[execution.jobDocument.afr_ota.streamname: AFR_OTA-945d320b-a18b-441b-b435-4a18d4e7671f]
    256 21255 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[execution.jobDocument.afr_ota.protocols: ["MQTT"]]
    257 21256 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[filepath: aws_demos.bin]
    258 21257 [OTA Agent Task] [ota.c:1684] [INFO] [OTA] Extracted parameter: [key: value]=[filesize: 1164016]
    259 21258 [OTA Agent Task] [ota.c:1684] [INFO] [OTA] Extracted parameter: [key: value]=[fileid: 0]
    260 21259 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[certfile: ecdsa-sha256-signer.crt.pem]
    261 21260 [OTA Agent Task] [ota.c:1575] [INFO] [OTA] Extracted parameter [ sig-sha256-ecdsa: MEQCIE1SFkIHHiZAvkPpu6McJtx7SYoD... ]
    262 21261 [OTA Agent Task] [ota.c:1684] [INFO] [OTA] Extracted parameter: [key: value]=[fileType: 0]
    263 21262 [OTA Agent Task] [ota.c:2199] [INFO] [OTA] Job document was accepted. Attempting to begin the update.
    264 21263 [OTA Agent Task] [ota.c:2323] [INFO] [OTA] Job parsing success: OtaJobParseErr_t=OtaJobParseErrNone, Job name=AFR_OTA-9702f1a3-b747-4c3e-a0eb-a3b0cf83ddbb
    265 21318 [iot_thread] [ota_demo_core_mqtt.c:1850] [INFO] [MQTT]  Received: 0   Queued: 0   Processed: 0   Dropped: 0
    266 21418 [iot_thread] [ota_demo_core_mqtt.c:1850] [INFO] [MQTT]  Received: 0   Queued: 0   Processed: 0   Dropped: 0
    267 21469 [OTA Agent Task] [ota.c:938] [INFO] [OTA] Setting OTA data interface.
    268 21470 [OTA Agent Task] [ota.c:2839] [INFO] [OTA] Current State=[CreatingFile], Event=[ReceivedJobDocument], New state=[CreatingFile]
    269 21482 [MQTT Agent Task] [core_mqtt.c:886] [INFO] [MQTT] Packet received. ReceivedBytes=3.
    270 21483 [OTA Agent Task] [ota_demo_core_mqtt.c:1503] [INFO] [MQTT] SUBSCRIBED to topic $aws/things/__test_infra_thing71/streams/AFR_OTA-945d320b-a18b-441b-b435-4a18d4e7671f/data/cbor to bro
    271 21484 [OTA Agent Task] [ota.c:2839] [INFO] [OTA] Current State=[RequestingFileBlock], Event=[CreateFile], New state=[RequestingFileBlock]
    272 21518 [iot_thread] [ota_demo_core_mqtt.c:1850] [INFO] [MQTT]  Received: 0   Queued: 0   Processed: 0   Dropped: 0
    273 21532 [MQTT Agent Task] [core_mqtt_agent_command_functions.c:76] [INFO] [MQTT] Publishing message to $aws/things/__test_infra_thing71/streams/AFR_OTA-945d320b-a18b-441b-b435-4a18d4e7671f/
    274 21534 [OTA Agent Task] [ota_demo_core_mqtt.c:1553] [INFO] [MQTT] Sent PUBLISH packet to broker $aws/things/__test_infra_thing71/streams/AFR_OTA-945d320b-a18b-441b-b435-4a18d4e7671f/get/cbor
    275 21534 [OTA Agent Task] [ota_mqtt.c:1112] [INFO] [OTA] Published to MQTT topic to request the next block: topic=$aws/things/__test_infra_thing71/streams/AFR_OTA-945d320b-a18b-441b-b435-4a1
    276 21537 [OTA Agent Task] [ota.c:2839] [INFO] [OTA] Current State=[WaitingForFileBlock], Event=[RequestFileBlock], New state=[WaitingForFileBlock]
    277 21558 [MQTT Agent Task] [core_mqtt.c:886] [INFO] [MQTT] Packet received. ReceivedBytes=4217.
    278 21559 [MQTT Agent Task] [core_mqtt.c:1045] [INFO] [MQTT] De-serialized incoming PUBLISH packet: DeserializerResult=MQTTSuccess.
    279 21560 [MQTT Agent Task] [core_mqtt.c:1058] [INFO] [MQTT] State record updated. New state=MQTTPublishDone.
    280 21561 [MQTT Agent Task] [ota_demo_core_mqtt.c:1026] [INFO] [MQTT] Received data message callback, size 4120.
    281 21563 [OTA Agent Task] [ota.c:2464] [INFO] [OTA] Received valid file block: Block index=0, Size=4096
    282 21566 [OTA Agent Task] [ota.c:2683] [INFO] [OTA] Number of blocks remaining: 284
     
    ... // Output removed for brevity
     
    3672 42745 [OTA Agent Task] [ota.c:2464] [INFO] [OTA] Received valid file block: Block index=284, Size=752
    3673 42747 [OTA Agent Task] [ota.c:2633] [INFO] [OTA] Received final block of the update.
    (428298) ota_pal: No such certificate file: ecdsa-sha256-signer.crt.pem. Using certificate in ota_demo_config.h.
    3674 42818 [iot_thread] [ota_demo_core_mqtt.c:1850] [INFO] [MQTT]  Received: 285   Queued: 285   Processed: 284   Dropped: 0
    3675 42918 [iot_thread] [ota_demo_core_mqtt.c:1850] [INFO] [MQTT]  Received: 285   Queued: 285   Processed: 284   Dropped: 0
     
    ... // Output removed for brevity
     
    3678 43197 [OTA Agent Task] [ota.c:2654] [INFO] [OTA] Received entire update and validated the signature.
    3685 43215 [OTA Agent Task] [ota_demo_core_mqtt.c:862] [INFO] [MQTT] Received OtaJobEventActivate callback from OTA Agent.
     
    ... // Output removed for brevity
     
    2 39 [iot_thread] [INFO ][DEMO][390] ---------STARTING DEMO---------
     
    [0;32mI (3633) WIFI: WIFI_EVENT_STA_CONNECTED
    [0;32mI (4373) WIFI: SYSTEM_EVENT_STA_GOT_IP
     
    ... // Output removed for brevity 
     
    4 351 [sys_evt] [INFO ][DEMO][3510] Connected to WiFi access point, ip address: 255.255.255.0.
    5 351 [iot_thread] [INFO ][DEMO][3510] Successfully initialized the demo. Network type for the demo: 1
    6 351 [iot_thread] [ota_demo_core_mqtt.c:1902] [INFO] [MQTT] OTA over MQTT demo, Application version 0.9.1
    7 351 [iot_thread] [ota_demo_core_mqtt.c:1323] [INFO] [MQTT] Creating a TLS connection to <endpoint>-ats.iot.us-west-2.amazonaws.com:8883.
    9 718 [iot_thread] [core_mqtt.c:886] [INFO] [MQTT] Packet received. ReceivedBytes=2.
    10 718 [iot_thread] [core_mqtt_serializer.c:970] [INFO] [MQTT] CONNACK session present bit not set.
    11 718 [iot_thread] [core_mqtt_serializer.c:912] [INFO] [MQTT] Connection accepted.
     
    ... // Output removed for brevity
     
    17 736 [OTA Agent Task] [ota_demo_core_mqtt.c:1503] [INFO] [MQTT] SUBSCRIBED to topic $aws/things/__test_infra_thing71/jobs/notify-next to broker.
    18 737 [OTA Agent Task] [ota_mqtt.c:381] [INFO] [OTA] Subscribed to MQTT topic: $aws/things/__test_infra_thing71/jobs/notify-next
    30 818 [iot_thread] [ota_demo_core_mqtt.c:1850] [INFO] [MQTT]  Received: 0   Queued: 0   Processed: 0   Dropped: 0
    31 819 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[execution.jobId: AFR_OTA-9702f1a3-b747-4c3e-a0eb-a3b0cf83ddbb]
    32 820 [OTA Agent Task] [ota.c:1684] [INFO] [OTA] Extracted parameter: [key: value]=[execution.statusDetails.updatedBy: 589824]
    33 822 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[execution.jobDocument.afr_ota.streamname: AFR_OTA-945d320b-a18b-441b-b435-4a18d4e7671f]
    34 823 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[execution.jobDocument.afr_ota.protocols: ["MQTT"]]
    35 824 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[filepath: aws_demos.bin]
    36 825 [OTA Agent Task] [ota.c:1684] [INFO] [OTA] Extracted parameter: [key: value]=[filesize: 1164016]
    37 826 [OTA Agent Task] [ota.c:1684] [INFO] [OTA] Extracted parameter: [key: value]=[fileid: 0]
    38 827 [OTA Agent Task] [ota.c:1645] [INFO] [OTA] Extracted parameter: [key: value]=[certfile: ecdsa-sha256-signer.crt.pem]
    39 828 [OTA Agent Task] [ota.c:1575] [INFO] [OTA] Extracted parameter [ sig-sha256-ecdsa: MEQCIE1SFkIHHiZAvkPpu6McJtx7SYoD... ]
    40 829 [OTA Agent Task] [ota.c:1684] [INFO] [OTA] Extracted parameter: [key: value]=[fileType: 0]
    41 830 [OTA Agent Task] [ota.c:2102] [INFO] [OTA] In self test mode.
    42 830 [OTA Agent Task] [ota.c:1936] [INFO] [OTA] New image has a higher version number than the current image: New image version=0.9.1, Previous image version=0.9.0
    43 832 [OTA Agent Task] [ota.c:2120] [INFO] [OTA] Image version is valid: Begin testing file: File ID=0
    53 896 [OTA Agent Task] [ota.c:794] [INFO] [OTA] Beginning self-test.
    62 971 [OTA Agent Task] [ota_demo_core_mqtt.c:1553] [INFO] [MQTT] Sent PUBLISH packet to broker $aws/things/__test_infra_thing71/jobs/AFR_OTA-9702f1a3-b747-4c3e-a0eb-a3b0cf83ddbb/update to br63 971 [MQTT Agent Task] [core_mqtt.c:1045] [INFO] [MQTT] De-serialized incoming PUBLISH packet: DeserializerResult=MQTTSuccess.
    65 973 [MQTT Agent Task] [core_mqtt.c:1058] [INFO] [MQTT] State record updated. New state=MQTTPublishDone.
    64 973 [OTA Agent Task] [ota_demo_core_mqtt.c:902] [INFO] [MQTT] Successfully updated with the new image.
```