DESK-MX8M-L/Peripherals/Audio
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Contents
Peripheral Audio[edit | edit source]
Access to the audio interface is provided by ALSA (Advanced Linux Sound Architecture), which consists in a kernel driver and a users space library for application developers. A set of standard tools (alsa-utils) can be used for simple management of the audio codec.
Device tree configuration[edit | edit source]
MITO 8M Mini[edit | edit source]
Here below an example of device tree configuration used on standard DAVE's kit for MITO 8M Mini:
From imx8mm-mito8mmini-sbcx.dts it is possible to find the codec SSI interface configuration:
...
...
sound {
compatible = "simple-audio-card";
simple-audio-card,format = "i2s";
simple-audio-card,name = "SBCX_TLV320";
simple-audio-card,bitclock-master = <&codec_dai>;
simple-audio-card,frame-master = <&codec_dai>;
simple-audio-card,widgets =
"Headphone", "Headphone Jack",
"Line", "Line In",
"Microphone", "Mic Jack";
simple-audio-card,routing =
"Speaker", "SPK",
"Headphone Jack", "HPL",
"Headphone Jack", "HPR",
"MIC1LP", "Line In",
"MIC1LM", "Line In",
"MIC1RP", "Mic Jack",
"Mic Jack", "MICBIAS";
simple-audio-card,cpu {
sound-dai = <&sai2>;
};
codec_dai: simple-audio-card,codec {
sound-dai = <&codec>;
system-clock-frequency = <24000000>;
};
};
...
&sai2 {
#sound-dai-cells = <0>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sai2>;
pinctrl-1 = <&pinctrl_codec_en>;
assigned-clocks = <&clk IMX8MM_CLK_SAI2>;
assigned-clock-parents = <&clk IMX8MM_AUDIO_PLL1_OUT>;
assigned-clock-rates = <24576000>;
status = "okay";
};
...
&iomuxc {
...
pinctrl_codec_en: codecen {
fsl,pins = <
MX8MM_IOMUXC_SAI3_RXFS_GPIO4_IO28 0x19
>;
};
...
...
From imx8mm-mito8mmini.dtsi:
...
...
&iomuxc {
...
pinctrl_sai2: sai2grp {
fsl,pins = <
MX8MM_IOMUXC_SAI2_MCLK_SAI2_MCLK 0xd6
MX8MM_IOMUXC_SAI2_TXFS_SAI2_TX_SYNC 0xd6
MX8MM_IOMUXC_SAI2_TXC_SAI2_TX_BCLK 0xd6
MX8MM_IOMUXC_SAI2_TXD0_SAI2_TX_DATA0 0xd6
MX8MM_IOMUXC_SAI2_RXFS_SAI2_RX_SYNC 0xd6
MX8MM_IOMUXC_SAI2_RXC_SAI2_RX_BCLK 0xd6
MX8MM_IOMUXC_SAI2_RXD0_SAI2_RX_DATA0 0xd6
>;
};
...
pinctrl_codec_en: codecen {
fsl,pins = <
MX8MM_IOMUXC_SAI3_RXFS_GPIO4_IO28 0x19
>;
};
...
...
Accessing the peripheral[edit | edit source]
Linux messages at boot time[edit | edit source]
... ... [ 3.038735] ALSA device list: [ 3.038739] #0: SBCX_TLV320 ... ...
To list the audio sound cards just use the aplay utility:
root@desk-mx8mm:~# aplay -l **** List of PLAYBACK Hardware Devices **** card 0: SBCXTLV320 [SBCX_TLV320], device 0: 30020000.sai-tlv320aic31xx-hifi tlv320aic31xx-hifi-0 [30020000.sai-tlv320aic31xx-hifi tlv320aic31xx-hifi-0] Subdevices: 1/1 Subdevice #0: subdevice #0 root@desk-mx8mm:~#
Usage alsa-utils[edit | edit source]
In order to unmute the speaker the amixer utility can be used.
root@desk-mx8mm:~# amixer sset "Speaker" on Simple mixer control 'Speaker',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] root@desk-mx8mm:~# amixer sset "Speaker Analog" 100 Simple mixer control 'Speaker Analog',0 Capabilities: pvolume pvolume-joined Playback channels: Mono Limits: Playback 0 - 127 Mono: Playback 100 [79%] [-13.50dB] root@desk-mx8mm:~# amixer sset "Speaker Driver" on 2 Simple mixer control 'Speaker Driver',0 Capabilities: pvolume pvolume-joined pswitch pswitch-joined Playback channels: Mono Limits: Playback 0 - 3 Mono: Playback 2 [67%] [18.00dB] [on] root@desk-mx8mm:~# amixer sset "DAC" 100 Simple mixer control 'DAC',0 Capabilities: pvolume Playback channels: Front Left - Front Right Limits: Playback 0 - 175 Mono: Front Left: Playback 100 [57%] [-13.50dB] Front Right: Playback 100 [57%] [-13.50dB] root@desk-mx8mm:~# amixer sset "Output Left From Left DAC" on Simple mixer control 'Output Left From Left DAC',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] root@desk-mx8mm:~#
To perform a sound, execute the command:
root@desk-mx8mm:~# speaker-test sim speaker-test 1.2.6 Playback device is default Stream parameters are 48000Hz, S16_LE, 1 channels Using 16 octaves of pink noise Rate set to 48000Hz (requested 48000Hz) Buffer size range from 3840 to 5760 Period size range from 1920 to 1920 Using max buffer size 5760 Periods = 4 was set period_size = 1920 was set buffer_size = 5760 0 - Front Left
Additional information[edit | edit source]
Information about alsa-utils can be found on ALSA project wiki pages
