Hi Jonathan, all.
I'm puzzled by your "dtoverlay=" observation as that certainly was not required on either my Pi3 or Pi4 running the same Buster image. I wonder if some of the confusion has to do with specifics of the OS you have; what updates it has received. When I first downloaded Buster it was before the DRAWS/udrc device tree files had hit; I had to perform an update before it would work.
In short, to get DRAWS/udrc recognized, all I did was:
1. Download and burn a new image - I've used both Raspbian Buster "Lite" as well as the full desktop image - same results.
2. While doing the initial setup of the Pi to create an empty ssh file in "boot", I also add to config.txt the famous:
and, to save having to change ALSA devices when running alsamixer:
# Enable audio (loads snd_bcm2835)
# DRAWS: May as well disable if you don't need this
# dtparam=audio=on
And boot. We're done.
aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: udrc [udrc], device 0: bcm2835-i2s-tlv320aic32x4-hifi tlv320aic32x4-hifi-0 []
Subdevices: 1 / 1
Subdevice #0: subdevice #0
The "July 10" label on Lite on the download page might not be accurate:
uname -a
Linux raspberrypi 4.19.57-v7l+ #1244 SMP Thu Jul 4 18:48:07 BST 2019 armv7l GNU/Linux
But it indeed is working on a Pi 3 and Pi 4. I'd recommend doing a system update in any case.
sudo apt-get update && sudo apt-get -y dist-upgrade
After reboot, on the Pi 4:
uname -a
Linux raspberrypi 4.19.66-v7l+ #1253 SMP Thu Aug 15 12:02:08 BST 2019 armv7l GNU/Linux
Move the same SD card to the Pi 3:
pi@raspberrypi:~ $ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: udrc [udrc], device 0: bcm2835-i2s-tlv320aic32x4-hifi tlv320aic32x4-hifi-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0
pi@raspberrypi:~ $ uname -a
Linux raspberrypi 4.19.66+ #1253 Thu Aug 15 11:37:30 BST 2019 armv6l GNU/Linux
This is what we should expect.
For hams new to all this I wrote up a short guide that only goes as far as the above; configuring applications without the support of the myriad of scripts will be daunting for some. I intend to write some follow up guides for the apps I'm using (mostly packet related at this point).
Cheers all
Mike