Inside, a low-power Raspberry Pi would do well, but an amplifier is needed for the speaker.
All that’s left of the interior is the speaker, and there’s room for new hardware. Something that has been on my to-do list for too long is an old Philips radio ( Figure 6 and 7). You can also see the AUX Out on the picture, which allows the IQaudio Codec Zero to act as a feed to an amplifier or active speakers. Youll be thrilled to discover that its one of the best video players for your Raspberry Pi device, and it includes built-in codecs, which saves you time. Sudo alsactl restore -f IQaudIO_Codec_AUXIN_record_and_HP_playback.state To select AUX In as recording source, you have to type the following in a terminal: If you want to connect an external audio source, you can solder suitable jacks to the IQaudio Codec Zero. This can then be played back with aplay test.wav.
For a test recording, arecord -device=hw:1,0 -format S16_LE -rate 44100 -c2 test.wav can be used in the terminal to start a test recording with the microphone and end it with CTRL+C. Using sudo alsactl restore -f IQaudIO_Codec_OnboardMIC_record_and_SPK_playback.state selects the microphone as the recording source. state files in the cloned Pi codec folder help to get the appropriate settings for recording via microphone. If you are unhappy with the sound, you can connect an external microphone. The MEMS microphone on the board won’t win any awards in the “recording quality” category, but it does its job. Or you can use the Raspberry Pi in conjunction with Edge Impulse to record data. This way, a smart speaker can be realized - e.g., with voice2json. With the built-in microphone, the Raspberry Pi can record audio. A quick and easy installation! Microphone, AUX-In and AUX-Out From now on all sounds will be output via IQaudio Codec Zero. After that, speaker-test -t wav -c 1 should make a front left sound from the speaker. In the terminal change to the created folder Pi-Codec and execute the command sudo alsactl restore -f IQaudIO_Codec_Playback_Only.state. To do this, a Git repository is cloned via terminal with git clone. The fastest way is to reload the provided settings from IQaudio. It is necessary to adjust a few parameters in the Advanced Linux Sound Architecture ( ALSA) settings. If a terminal is opened now, a speaker test can be started with speaker-test -t wav -c 1. After the internal audio codec of the Raspberry Pi has been deactivated according to the instructions, the IQaudio now remains in the system as the default sound card. First, the output volume should be reduced to a minimum. If you’re an OEM that requires a large number of these boards, please contact us.However, there are still a few steps necessary that are not directly described in the IQaudio Codec Zero manual. Note that this board is not available to the general public. You can use the same play/record command as in the previous example. Depending on the microphone you’re using you might have to set the Mic bias jumper to enable a bias voltage to your microphone (electret microphones will need this, dynamic microphones should not have Mic bias enabled). Record 5 seconds of audio and play back recording arecord -c 2 -r 44100 -f S16_LE -d 5 x.wav aplay x.wav Recording from an external microphone Set the jumper first to select the onboard microphone: Note that the RCA output connector and the pin header is connected to the Headphone output, not to the line-out of the codec! Recording from the onboard-microphone Simple record/playback settings amixer set 'Headphone' 103Īmixer set 'Capture Attenuate Switch (-6dB)' 'on' There are lots of mixer controls, it’s important to set these correctly. Microphone selector (onboard or external)