Difference between revisions of "ALSA"
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==Usage== | ==Usage== | ||
* load the ALSA drivers: | * load the ALSA drivers: | ||
| + | <pre class="apf"> | ||
# modprobe spi_imx | # modprobe spi_imx | ||
# modprobe snd-imx-alsa-tsc2102 | # modprobe snd-imx-alsa-tsc2102 | ||
| Line 40: | Line 41: | ||
hwmon 948 1 tsc2102 | hwmon 948 1 tsc2102 | ||
spi_imx 9024 0 | spi_imx 9024 0 | ||
| − | + | </pre> | |
* if you want OSS support: | * if you want OSS support: | ||
| + | <pre class="apf"> | ||
modprobe snd-pcm-oss | modprobe snd-pcm-oss | ||
modprobe snd-mixer-oss | modprobe snd-mixer-oss | ||
| + | </pre> | ||
* If you want MIDI sequencer support: | * If you want MIDI sequencer support: | ||
| + | <pre class="apf"> | ||
modprobe snd-seq | modprobe snd-seq | ||
modprobe snd-seq-device | modprobe snd-seq-device | ||
| + | </pre> | ||
===Loading script=== | ===Loading script=== | ||
If you want the drivers to be loaded automatically during each boot, you can add a script in ''/etc/init.d/''. For example: | If you want the drivers to be loaded automatically during each boot, you can add a script in ''/etc/init.d/''. For example: | ||
| − | + | <pre class="apf"> | |
# vi /etc/init.d/S60alsa | # vi /etc/init.d/S60alsa | ||
| + | </pre> | ||
<source lang="bash"> | <source lang="bash"> | ||
#!/bin/sh | #!/bin/sh | ||
| Line 58: | Line 64: | ||
modprobe snd-imx-alsa-tsc2102 | modprobe snd-imx-alsa-tsc2102 | ||
</source> | </source> | ||
| − | + | <pre class="apf"> | |
# chmod a+x /etc/init.d/S60alsa | # chmod a+x /etc/init.d/S60alsa | ||
| + | </pre> | ||
==Test== | ==Test== | ||
* Check if ALSA is running: | * Check if ALSA is running: | ||
| + | <pre class="apf"> | ||
# cat /proc/asound/version | # cat /proc/asound/version | ||
Advanced Linux Sound Architecture Driver Version 1.0.17. | Advanced Linux Sound Architecture Driver Version 1.0.17. | ||
| + | </pre> | ||
* To check if the [[TSC2102]] was detected as a sound chip: | * To check if the [[TSC2102]] was detected as a sound chip: | ||
| + | <pre class="apf"> | ||
# aplay -lL | # aplay -lL | ||
default:CARD=IMX-ALSA | default:CARD=IMX-ALSA | ||
| Line 81: | Line 91: | ||
0 [IMX-ALSA ]: IMXALSA - ARMADEUS IMX_ALSA | 0 [IMX-ALSA ]: IMXALSA - ARMADEUS IMX_ALSA | ||
ARMADEUS IMX_ALSA | ARMADEUS IMX_ALSA | ||
| − | + | </pre> | |
* To play a test sound: | * To play a test sound: | ||
| + | <pre class="apf"> | ||
# aplay /usr/share/sounds/alsa/Side_Left.wav | # aplay /usr/share/sounds/alsa/Side_Left.wav | ||
Playing WAVE '/usr/share/sounds/alsa/Side_Left.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono | Playing WAVE '/usr/share/sounds/alsa/Side_Left.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono | ||
| + | </pre> | ||
Note: the audio file Side_Left.wav can be copied from your Linux host (if not already on your rootfs) | Note: the audio file Side_Left.wav can be copied from your Linux host (if not already on your rootfs) | ||
Revision as of 10:55, 6 February 2009
This page will summarize the informations to use ALSA on your Armadeus boards.
Contents
Introduction
ALSA stands for Advanced Linux Sound Architecture and provides audio and MIDI functionality to the Linux operating system. Everyone wanting to write portable & state of the art Linux applications dealing with sound should consider using ALSA.
ALSA is composed of a low level part (target specific Linux drivers) and a userspace library (libasound).
Hardware
On the i.MX family, used on the Armadeus boards, (good quality) sound can be produced that way: the i.MX takes PCM data (ALSA format) from memory and send them (through DMA) to its SSI interface. This one converts the data to a serial stream of bits in the I2S format. That stream is sent to a CODEC like the TSC2102 on the APF9328 or the TSC2101 on the APF27. The stream is then converted by the CODEC's DAC to an analog sound.
ALSA Soc
On the APF boards we are going to use Embedded version of ALSA: ALSA Soc ->
- http://opensource.wolfsonmicro.com/node/6
- http://www.rpsys.net/openzaurus/patches/alsa/info.html
- http://alsa-project.org/main/index.php/ASoC
But for the moment only "standard" version is functionnal.
Installation
ALSA is now by default installed on the standard Armadeus rootfs. If you want to change default configuration, you can consult this wiki page: ALSA_Installation
Usage
- load the ALSA drivers:
# modprobe spi_imx # modprobe snd-imx-alsa-tsc2102 TI TSC2102 driver initializing audio_dma_request done (8) audio_dma_request done (9) audio support initialized # lsmod Module Size Used by Not tainted snd_imx_alsa_tsc2102 7204 0 snd_pcm 50760 1 snd_imx_alsa_tsc2102 snd_timer 14084 1 snd_pcm snd_page_alloc 3208 1 snd_pcm snd 28916 3 snd_imx_alsa_tsc2102,snd_pcm,snd_timer soundcore 3332 1 snd tsc2102 10256 1 snd_imx_alsa_tsc2102 hwmon 948 1 tsc2102 spi_imx 9024 0
- if you want OSS support:
modprobe snd-pcm-oss modprobe snd-mixer-oss
- If you want MIDI sequencer support:
modprobe snd-seq modprobe snd-seq-device
Loading script
If you want the drivers to be loaded automatically during each boot, you can add a script in /etc/init.d/. For example:
# vi /etc/init.d/S60alsa
#!/bin/sh
modprobe spi_imx
modprobe snd-imx-alsa-tsc2102
# chmod a+x /etc/init.d/S60alsa
Test
- Check if ALSA is running:
# cat /proc/asound/version Advanced Linux Sound Architecture Driver Version 1.0.17.
- To check if the TSC2102 was detected as a sound chip:
# aplay -lL
default:CARD=IMX-ALSA
ARMADEUS IMX_ALSA, imx alsa pcm
Default Audio Device
null
Discard all samples (playback) or generate zero samples (capture)
**** List of PLAYBACK Hardware Devices ****
card 0: IMX-ALSA [ARMADEUS IMX_ALSA], device 0: IMX PCM [imx alsa pcm]
Subdevices: 1/1
Subdevice #0: subdevice #0
or
# cat /proc/asound/cards
0 [IMX-ALSA ]: IMXALSA - ARMADEUS IMX_ALSA
ARMADEUS IMX_ALSA
- To play a test sound:
# aplay /usr/share/sounds/alsa/Side_Left.wav Playing WAVE '/usr/share/sounds/alsa/Side_Left.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
Note: the audio file Side_Left.wav can be copied from your Linux host (if not already on your rootfs)
Going further
Now that ALSA is working, you can switch to serious things ;-) ->
Links
- http://www.alsa-project.org/
- http://free-electrons.com/formations/audio
- http://alsa-project.org/main/index.php/DevEmbedded
- http://alsa.opensrc.org/index.php/WritingAnAlsaDriver + http://www.alsa-project.org/~tiwai/writing-an-alsa-driver.pdf
- Introduction to Sound Programming with ALSA on Linux Journal
- PCM format on Wikipedia & I2S bus on Wikipedia
