Well, it turned out that this is working very well. The issue was in my hardware:
1) My AXR0 line was mistakenly connected to the other line. 2) My PCM5102A dac board required 5V, but I was feeding 3.3V After these were corrected I could hear audio from my DAC board. BTW, I noticed TI forum post had typo system-clock-direction = "out"; => system-clock-direction-out; (see https://www.kernel.org/doc/Documentation/devicetree/bindings/sound/simple-card.txt) Oscilloscope was my friend and learned it is a best tool to check I2S line outputs (at leaset for this initial design stage). On Friday, October 5, 2018 at 3:20:47 AM UTC+9, [email protected] wrote: > > Hello. > I am following the below post and trying to play audio on PCM5102A I2S > board, connected to PocketBeagle header. > > > https://e2e.ti.com/support/processors/f/791/t/458085?Suggestion-for-improving-the-Sitara-Linux-Audio-DAC-Example > > I am using the official Debian image (with PCM5102A driver eneabled). > > So far (according to dmesg output) the drivers are initialized and newly > created ALSA output device can be seen. > > >[ 1.553224] asoc-simple-card sound: ASoC: binding > davinci-mcasp.0-pcm5102a-hifi > >[ 1.662191] asoc-simple-card sound: pcm5102a-hifi 48038000.mcasp mapping > ok > >[ 1.666676] asoc-simple-card sound: ASoC: no DMI vendor name! > > >[ 1.697221] ALSA device list: > >[ 1.697236] #0: I2S slave playback > > The problem is, trying 'aplay', but no sound on I2S device. > > The header pins are listed as follows in dtb. > > 0x190 0x8 /* P1.36 mcasp0_aclkx */ > 0x194 0x8 /* P1.33 mcasp0_fsx */ > 0x198 0x8 /* P2.32 mcasp0_axr0 */ > > I examined the pins with osilloscope, but I think there is no signal there. > (Looks like P1.36 left open, P1.33, P2.32 pulled down to GND without > signal?) > > I think there are at least two points I should look into next, but I am > not sure how to. > > 1) mcasp0 driver is it working? > 2) pinmux functioning so that I am seeing mcasp pins on P1.36/P1.33/P2.34 > physical pins? > > Sorry I am new to pinmuxing. > Maybe looking into some debugfs files I can be sure my pinmux definitions > are working as expected? > > FYI. Here are lines containing mcasp from debugfs: > > /sys/kernel/debug/pinctrl/pinctrl_handles: > > >device: 48038000.mcasp current state: default > > state: default > > type: MUX_GROUP controller pinctrl-single group: mcasp0_pins (313) > function: mcasp0_pins (313) > > /sys/kernel/debug/pinctrl/pinctrl-maps > > >device 48038000.mcasp > >state default > >type MUX_GROUP (2) > >controlling device 44e10800.pinmux > >group mcasp0_pins > >function mcasp0_pins > > /sys/kernel/debug/pinctrl/44e10800.pinmux/pingroups: > > >group: mcasp0_pins > >pin 100 (PIN100) > >pin 101 (PIN101) > >pin 102 (PIN102) > > /sys/kernel/debug/pinctrl/44e10800.pinmux/pinmux-functions: > > >function: mcasp0_pins, groups = [ mcasp0_pins ] > > /sys/kernel/debug/pinctrl/44e10800.pinmux/pinmux-pins: > > >pin 100 (PIN100): 48038000.mcasp (GPIO UNCLAIMED) function mcasp0_pins > group mcasp0_pins > >pin 101 (PIN101): 48038000.mcasp (GPIO UNCLAIMED) function mcasp0_pins > group mcasp0_pins > >pin 102 (PIN102): 48038000.mcasp (GPIO UNCLAIMED) function mcasp0_pins > group mcasp0_pins > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/5cbef026-ae55-4bd5-b8a1-ff81806000ca%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
