Introduction

Hello everyone, I am Morgan, the principal engineer of Nuvoton Technology. Today, I will show you how to record and play audio with Mbed OS on NuMaker-IoT-M487 development board. Open Chrome browser, and enter the URL https://ide.mbed.com to use the Mbed Online Compiler. After log in, make sure that NuMaker-IoT-M487 board already selected in the upper right corner. If not, please refer Nuvoton IoT Tutorial series “Get Started with Mbed OS” which has a detailed description of how to add a board. Click the “New” on the left of menu bar, a “Create new program” window will be displayed. You can see that the Platform has been set to NuMaker-IoT-M487. In the Template, select the "NuMaker audio playback" for this tutorial. Then click OK. Now you can see that the sample code has loaded on the page. The sample code has three functions: 1. Record 10 seconds sound and save to Micro SD card 2. Play sounds stored in Micro SD card 3. Loopback. Record sound and play it immediately. Click main.cpp to open it. Then scroll down to line 421. You can see the functions calls here. It set to loopback only. Let’s do a little modification. Hit a key on console to start record 10 seconds then play it, and then do loopback. printf("Press a key to start recording 10 seconds..."); getchar(); demo_record(); demo_play(); demo_loopback(); Save it and click “Compile” to build the code. Compilation takes a while, please wait. After the compilation is completed, “Success” will appear in the compile output window. The browser downloads the binary firmware file directly after a successful compiling. It will be saved in a default download folder. In Chrome, you can click download file and select “Show in folder”. Please plug an earphone commonly used for mobile phone in headphone jack on NuMaker-IoT-M487 board. For demonstration, we use a headphone splitter cable to connect a microphone and a speaker. Do not put the microphone and speaker too close to avoid feedback howling. Then connect the USB port to your computer and make sure the onboard LED lights up. Back to the folder you just download the binary firmware file (NuMaker-mbed-AudioPlayback-example.NUMAKER_IOT_M487.bin). Drag and drop the file to NuMicro MCU drive. You will see the copying progress dialog box. Please find the virtual COM port assigned for NuMaker-IoT-M487 in Device Manager. In the demonstration, the “Nu-Link Virtual Com Port” is COMx. Then use your favorite terminal tool. Here we use Putty. Open the COMx port with 9600 baud rate. And no flow control settings. Then “Open” it. Press “Reset” on board to run the firmware again. Press a key on terminal to start record. Speak for about 10 seconds, then your voice will be played. That’s all for this tutorial. Thank you for watching. Welcome to subscribe to our channel. If you want to get more information, please contact us “SalesSupport@nuvoton.com” - For more information, please visit Nuvoton Technology Website: https://bit.ly/3hVdcmC Buy now: https://direct.nuvoton.com/tw/numaker-iot-m487 Contact us: SalesSupport@nuvoton.com #tool #training #learning #intermediate #en

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