No I2S signal (output) - probably soft issue

[acourdavault]

Hello everyone,

I have a little mystery,

I have a BeagleBone Black Wireless with OS
Linux beaglebone 4.9.45-ti-r57 #1 SMP PREEMPT Fri Aug 25 22:58:38 UTC 2017 armv7l

And when I play sound (48kHz 2 channels 32 signed LE WAV) with aplay I have no signal at all on the pin P9-31 (bitclock) nor P9-29, nor P9-28
I have an oscilloscope, to check this

I managed with this board to use the I2s a few weeks back with aplay and even by sending audio to it via bluetooth, but for a reason i don't know it does not work anymore.

I started up fresh from the official image, and so far i've done this:

• check audio cards with aplay -Land -l (see ouputs below)
• installed pulseaudio and pulseaudio-module-bluetooth
• changed default settings to 48000Hz, 2 channels s32le
• check pactl list sinks and the sink is active when i play audio
• checked the pactl info (see below)
• checked that HDMII (video) is working

All settings seems fine, the pin used are:
SData in 2 <=> P9-pin 28
LRClock in 2 <=> P9-pin 29
BClock in 2 <=> P9-pin 31
GND is on P9-45 but i also tried on P9-1 and P9-2

(pinout below for info)
I expect this cabling to be right as it worked in the past...

Can anyone help me?

• should i reconfigure some pins?
• Would there be a setting in ALSA that i may have forgotten, or PULSEAUDIO?
• OR is it likely that my BBB has dead ports? (if so how could i test some other ports maybe to confirm?)

I know the I2S output is shared with the screen output, so i though i would not have to reconfigure pins

details

aplay

debian@beaglebone:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Black [TI BeagleBone Black], device 0: davinci-mcasp.0-hdmi-hifi.0 hdmi-hifi.0-0 []
  Subdevices: 1/1
  Subdevice #0: subdevice #0
debian@beaglebone:~$ aplay -L
default
    Playback/recording through the PulseAudio sound server
null
    Discard all samples (playback) or generate zero samples (capture)
sysdefault:CARD=Black
    TI BeagleBone Black,
    Default Audio Device
dmix:CARD=Black,DEV=0
    TI BeagleBone Black,
    Direct sample mixing device
dsnoop:CARD=Black,DEV=0
    TI BeagleBone Black,
    Direct sample snooping device
hw:CARD=Black,DEV=0
    TI BeagleBone Black,
    Direct hardware device without any conversions
plughw:CARD=Black,DEV=0
    TI BeagleBone Black,
    Hardware device with all software conversions

pactl info

Server String: /run/user/1000/pulse/native
Library Protocol Version: 32
Server Protocol Version: 32
Is Local: yes
Client Index: 28
Tile Size: 65496
User Name: debian
Host Name: beaglebone
Server Name: pulseaudio
Server Version: 10.0
Default Sample Specification: s32le 2ch 48000Hz
Default Channel Map: front-left,front-right
Default Sink: alsa_output.platform-sound.analog-stereo
Default Source: alsa_output.platform-sound.analog-stereo.monitor
Cookie: f45c:9a98

pinout

pin config

debian@beaglebone:~$ config-pin -i P9_31

Pin name: P9_31
Function if no cape loaded: gpio
Function if cape loaded: default gpio gpio_pu gpio_pd pwm spi pruout pruin
Function information: gpio3_14 default gpio3_14 gpio3_14 gpio3_14 ehrpwm0A spi1_sclk pr1_pru0_pru_r30_0 pr1_pru0_pru_r31_0
Cape: cape-universala cape-universaln cape-universalh cape-univ-audio
Kernel GPIO id: 110
PRU GPIO id: 142

debian@beaglebone:~$ config-pin -i P9_29

Pin name: P9_29
Function if no cape loaded: gpio
Function if cape loaded: default gpio gpio_pu gpio_pd pwm spi pruout pruin
Function information: gpio3_15 default gpio3_15 gpio3_15 gpio3_15 ehrpwm0B spi1_d0 pr1_pru0_pru_r30_1 pr1_pru0_pru_r31_1
Cape: cape-universala cape-universaln cape-universalh cape-univ-audio
Kernel GPIO id: 111
PRU GPIO id: 143

debian@beaglebone:~$ config-pin -i P9_28

Pin name: P9_28
Function if no cape loaded: gpio
Function if cape loaded: default gpio gpio_pu gpio_pd pwm spi pwm2 pruout pruin
Function information: gpio3_17 default gpio3_17 gpio3_17 gpio3_17 ehrpwm0_synci spi1_cs0 eCAP2_in_PWM2_out pr1_pru0_pru_r30_3 pr1_pru0_pru_r31_3
Cape: cape-universala cape-universaln cape-universalh cape-univ-audio
Kernel GPIO id: 113
PRU GPIO id: 145

debian@beaglebone:~$ config-pin -i P9_25

Pin name: P9_25
Function if no cape loaded: gpio
Function if cape loaded: default gpio gpio_pu gpio_pd qep pruout pruin
Function information: gpio3_21 default gpio3_21 gpio3_21 gpio3_21 eQEP0_strobe pr1_pru0_pru_r30_7 pr1_pru0_pru_r31_7
Cape: cape-universala cape-universaln cape-universalh cape-univ-audio
Kernel GPIO id: 117
PRU GPIO id: 149

[jadonk]

Can you run "perl /opt/scripts/device/bone/show-pins.pl" to get the current pin status?

What is the video resolution?

https://elinux.org/Beagleboard:BeagleBoneBlack_HDMI might be a bit informative. Audio output is only available at certain video resolutions.