[PROBLEM] MPD error "Failed to open ALSA" only occurs after coldstart

[gforster]

No prob.

The DMESG logs confirm the drivers for both audio devices fail to initialize during Linux boot. I'd suspect the power supply.

The PSU I've used with IQaudIO Pi-DigiAmp+ is XP Power VEH60US15 (15V/$A) I don't know what the other amp HAT requires.

The Suptronics X400 requires an input voltage in the range of 6-26V, the IQaudIO 12-24V.
I changed the power supply and tested with

• 12V, cabable of providing up to 5A
  
• 15V, capable of providing up to 10A
  

Neither one of these alternate power supplies did resolve the coldstart issue.
The max current drawn was 600mA, ie 9Watts.

As a second step,I did add a delay of 30 seconds to the boot process within /boot/config.txt in order to give the sound card more time to initialize:

Code:

bootcode_delay=30

The raspberry website describes at https://www.raspberrypi.org/documentatio...xt/boot.md
that the bootcode_delay command is particularly useful to insert a delay if the Pi and other devices are powered from the same power source, but the device takes longer to start up than the Pi. Try to set this value if the device detection is wrong on initial boot, but is correct if you soft-reboot the Pi without removing power from the other device.
Even this recommendation was specifically for a monitor, my hope was that this would also resolve the coldstart issue of the sound card.

Unfortunately, the delayed boot sequence did not resolve the coldstart. The boot time took 30 seconds longer (I also tried it with 60 seconds), but the "Failed to open ALSA" problem message was still there.

For me it is quite certain that the root cause of the problem is not moode, but something inside the OS boot trying to access the audio/sound card which is not responding correctly.

The workaround for me is to avoid a coldstart situation. Of course, this can't be prevented when the radio is powered-up for the first time. Instead of turning off the radio when it's not used, I just put it into sleep mode by a push-button managed through the GPIO handler of moode, which is then initiating the following command:

Code:

sudo shutdown now

Another push-button then restarts the radio by shorting GPIO#3 to GND. This is a warmstart and does not cause any ALSA failure.

Still don't understand why it is working fine during warmstart but not during coldstart. Would be great if someone finds out the root cause of this behaviour and how to overcome this.