I2S Raspberry Interface (3)

Update July 11, 2025

Some thoughts and tasks today. The project is the same I2S interface.

• Solved the truncation of THD74 audio on receive → menu item 920;
• Connected the I2S proto board to my RoLink shield. Works with pops.
• Dtoverlay=i2s-mmap not needed anymore
• dtparam=audio=on should load snd_bcm2835 for the headphone output
• dtoverlay=vc4-kms-v3d should add the support for HDMI audio.
• sudo nano /usr/lib/systemd/system/svxlink.service
• excellent read Writing an ALSA Driver

tom@rpi-i2s:~ $ sudo nano /usr/lib/systemd/system/svxlink.service
tom@rpi-i2s:~ $ sudo systemctl daemon-reload

Modified files – remember

• /etc/modprobe.d/cirrus_audio.conf
• /home/tom/.asoundrc
• /etc/asound.conf
• /etc/systemd/system/aplay.service

Aliases with arguments

• https://askubuntu.com/questions/626458/can-i-pass-arguments-to-an-alias-command

d () {
  num=${1:-5}
  dmesg |grep -iw usb|tail -$num
}

fnd () {
  num=${1:90}
  find . -type f -mtime $num
}