This tutorial is outdated. Please look here for the new tutorial.

You can skip this step, if you already have Raspbian installed on your compatible Raspberry Pi.

• Download Raspbian from here
• Unzip Raspbian and flash the image to an SD card. Here you find a step-by-step tutorial.

You need network connection for headless operation.

For using your Raspberry Pi without a monitor, you need to create an empty file named ssh on the boot partition of the SD card.

Create a file wpa_supplicant according to this guide.

Now put the SD card in your compatible Raspberry Pi and power it up.

Log in to your Raspberry Pi with the default credentials (user: pi, password: raspberry). Change the default password for security reasons.

passwd

Open the file /boot/config.txt for writing with any text editor of your choice. For simplicity we use nano, which is pre-installed on Raspbian:

sudo nano /boot/config.txt

Scroll down to this line:

#dtparam=i2s=on

and uncomment it (remove the # from the beginning of the line).

Save your changes and close the file.

Now open the file /etc/modules:

sudo nano /etc/modules

and add the following line to the end of the file:

snd-bcm2835

Save your changes and close the file.

Now reboot your Raspberry Pi to apply the changes:

sudo reboot

Let's do an intermediate check, if everything worked so far:

lsmod | grep snd_soc_bcm2835_i2s

If the output of this command is not empty, all went well so far!

If you encounter any problems up to this step, please be sure that you use the newest version of Raspbian on a supported hardware platform. In case it still doesn't work, please consider trying the steps on a fresh Raspbian installation. If you still encounter problems, please feel free to open an issue.

Please inform yourself about the tool rpi-update and the side effects it might have before executing the following commands.

If you have any important data on your Raspberry Pi, we recommend to do make a backup before continuing.

Please make sure that your Raspberry Pi has a working Internet connection.

We now need to install the tool rpi-update:

sudo apt-get update
sudo apt-get install rpi-update
sudo rpi-update

After about one minute the following prompt appears:

Would you like to proceed? (y/N)

Press y to continue the process. Make sure to inform yourself about the potential risks before you proceed.

The subsequent updating process takes about 4 minutes.

After the process has finished, please reboot your Raspberry Pi to activate the new firmware:

sudo reboot

Now install these dependencies for subsequent compliation of a kernel with the I2S module:

sudo apt-get install git bc libncurses5-dev bison flex libssl-dev

Now we come to the biggest step: Downloading and compling the kernel source - Let's go!

sudo wget https://raw.githubusercontent.com/notro/rpi-source/master/rpi-source -O /usr/bin/rpi-source
sudo chmod +x /usr/bin/rpi-source
/usr/bin/rpi-source -q --tag-update
rpi-source --skip-gcc

The last command will take about 10 minutes on a Raspberry Pi 3 Mod. B+, so it's time to grab a coffee :)

If the following prompt appears (after about 7 minutes), please hit Enter to accept the default response:

Code coverage for fuzzing (KCOV) [N/y/?] (NEW)

Compile the I2S module:

sudo mount -t debugfs debugs /sys/kernel/debug

Don't worry if it says: mount: /sys/kernel/debug: debugs already mounted or mount point busy. That's ok.

Now download the I2S module for the Raspberry Pi, written by Paul Creaser:

git clone https://github.com/PaulCreaser/rpi-i2s-audio

Load the I2C module statically:

cd rpi-i2s-audio
make -C /lib/modules/$(uname -r)/build M=$(pwd) modules
sudo insmod my-loader.ko

Now let's check if everything worked so far. Use this command to verify if the module has been loaded correctly:

lsmod | grep my_loader

Now let's use dmesg to read out the latest messages of the Kernel Ring Buffer:

dmesg | tail

Everything worked so far if you see a line like:

[X.XXXXXX] asoc-simple-card asoc-simple-card.0: snd-soc-dummy-dai <-> 3f203000.i2s mapping ok

In order to enable autostart for the I2S modules, the following commands have to be executed:

sudo cp my_loader.ko /lib/modules/$(uname -r)
echo 'my_loader' | sudo tee --append /etc/modules > /dev/null
sudo depmod -a
sudo modprobe my_loader

Now it's time for the hardware part before you can test your new setup!

Before you start working on the hardware connections, shutdown your Raspberry Pi:

sudo poweroff

and unplug the power cable.

• Connect the IM69D130 Microphone Shield2Go to your Raspberry Pi

Pin connection:

• Power up your Raspberry Pi

List available input devices with:

arecord -l

You should see a snd_rpi_simple_card.

You can record a wav file with this command:

arecord -D plughw:1 -c2 -r 48000 -f S32_LE -t wav -V stereo test.wav

By default, the sound level of the recording is very low, but so is the noise, hence you can easily amplify the output file e.g. using sox:

sudo apt-get install sox
sox test.wav test_norm.wav --norm=0 trim 10

--norm=0 normalizes the output file to 0 dB and trim 10 cuts the first 10 seconds of the audio file. This is recommended if you get a clipping peak in the beginning of the recording, because otherwise the normalization does not work correctly.

To sum this up; for recording a sequence of 10 seconds, normalizing it and playing it back you can use the following command:

arecord -D plughw:1 -c2 -r 48000 -f S32_LE -t wav -V stereo --duration 20 test.wav && sox test.wav test_norm.wav --norm=0 trim 10 && aplay test_norm.wav