/***********************************************************************                RPi 3B Aduio 3.5mm output* 说明：*     看到树莓派上一个3.5mm耳机口，从来没用过，折腾一下。**                                2018-7-13 深圳 宝安西乡 曾剑锋*********************************************************************/一、参考文档：1. 树莓派如何选择3.5mm耳机孔输出声音https://jingyan.baidu.com/article/64d05a02220053de55f73bbc.html

二、具体操作：1. sudo raspi-config2. 选择流程：Raspberry Pi 3 Model B Rev 1.2┌─────────┤ Raspberry Pi Software Configuration Tool (raspi-config) ├──────────┐│                                                                              ││    1 Change User Password           Change password for the current u        ││    2 Network Options                Configure network settings               ││    3 Boot Options                   Configure options for start-up           ││    4 Localisation Options           Set up language and regional sett        ││    5 Interfacing Options            Configure connections to peripher        ││    6 Overclock                      Configure overclocking for your P        ││    7 Advanced Options               Configure advanced settings          <---││    8 Update                         Update this tool to the latest ve        ││    9 About raspi-config             Information about this configurat        ││                                                                              ││                                                                              ││                                                                              ││                     <Select>                     <Finish>                    ││                                                                              │└──────────────────────────────────────────────────────────────────────────────┘┌─────────┤ Raspberry Pi Software Configuration Tool (raspi-config) ├──────────┐│                                                                              ││    A1 Expand Filesystem             Ensures that all of the SD card s        ││    A2 Overscan                      You may need to configure oversca        ││    A3 Memory Split                  Change the amount of memory made         ││    A4 Audio                         Force audio out through HDMI or 3    <---││    A5 Resolution                    Set a specific screen resolution         ││    A6 Pixel Doubling                Enable/Disable 2x2 pixel mapping         ││    A7 GL Driver                     Enable/Disable experimental deskt        ││                                                                              ││                                                                              ││                                                                              ││                                                                              ││                                                                              ││                     <Select>                     <Back>                      ││                                                                              │└──────────────────────────────────────────────────────────────────────────────┘┌──────────────────────────────────────────────────────────┐│ Choose the audio output                                  ││                                                          ││             0 Auto                                       ││             1 Force 3.5mm ('headphone') jack     <---    ││             2 Force HDMI                                 ││                                                          ││                                                          ││                                                          ││                                                          ││                                                          ││                                                          ││                                                          ││                                                          ││                                                          ││                                                          ││                                                          ││              <Ok>                  <Cancel>              ││                                                          │└──────────────────────────────────────────────────────────┘3. speaker-test -t sine