Puppi Raspberry Pi Hardware

[sickgut]

Lobster

I guess an external USB type sound card would work but surely
it would also require drivers.

Since Pi has no sound support yet, this is the perfect excuse to reach for
the soldering iron and build an external R-2R type DAC to get some
elementary 8 bit sound out of the GPIOs

Remember the Mod scene from days gone by?
I remember building a crude DAC for the LPT port on an old 386 PC then
writing software to send out samples from wav files one by one to the LPT port where
the DAC would convert the samples into analog voltages.
Filtering was very basic and consisted of a few capacitors and resistors.
No awards for "hi-fi" sound, but it worked suprisingly well given it's simplicity.

The output from the DAC can be connected to a pair of amplified PC speakers
thus saving the hassle of needing to build a small audio amp.

Since the Pi comes with gcc, then I assume it also has "usleep" which one
can use for a delay and timing between samples.

Once I get my Pi, whether sound support is available by then or not, I'm
gonna build myself one of these just for the fun of it.

The pin-outs of the Pi here:
(The pins of interest are GPIO 0 - 7 and of course 0v)

http://elinux.org/RPi_Low-level_peripherals

WTF i really cant believe they actually released the rasp pi with no official sound support yet in the software....

i think i just lost the last ounce of faith i had in the entire universe, also i feel like i just had some marketting managers weener in my mouth. I need to order some mouthwash online and then hide in seclusion for the next decade and reimerge when the rasp pi has sound.

[update]
however the analogue video connector means i can use my tv and unplug my ps/2 and replace it with the rasp pi and attach a mouse and keyboard instead of a ps/2 controller. Maybe ill only hide away in seclusion for 5 years instead of 10.

[update]
mouthwash altho delivered extremely quickly was not effective. Maybe a hotdog will fix that, replace the taste of one weener with another larger one.

[update]
need to wait till tomorrow till i can buy a hotdog. Ordered more mouthwash. Fingers crossed.

[Dave_G]

sickgut

Don't take my writing that the Pi has no sound support as gospel.
I only assumed it has none by what Lobster wrote.

[sickgut]

sickgut

Don't take my writing that the Pi has no sound support as gospel.
I only assumed it has none by what Lobster wrote.

after hastily setting up camp to live in seclusion to hide my sad and mudden face from the world, i came down from the mountain for a minute to check the raspberry pi site and it indeed doesnt have any sound support, altho the sound hardware is there. After confirming my worst fears, i have started on the long trek up the mountain again with more mouthwash this time.

When i here the happy beeps of 8 bit mame emulators running on the raspberry pi, i may come down from the mountain again to see what the fuss is about.

[humblesoul]

no sound support

usb?

[Dave_G]

sickgut wrote:

i may come down from the mountain again to see what the fuss is about.

Don't worry, you will know when to come down when the mountains echo to the sounds of beeps and bops. Hehehe !

From what I can remember, the frequency response extended to about 10Khz
but the SNR was only about 45dB or so.
Certainly OK to play sound clips and even music but like I said don't expect CD quality sound.

[Dave_G]

@humblesoul

I speak under correction but I think USB sound would also require drivers.

[humblesoul]

That'll teach me to click reply without reading all the preceding posts... one assumed usb sound was as generic and common as mouse, keyboard and web cam support in most distro's these days.

[Dave_G]

The reason I say that USB sound may require a driver is simply that
USB keyboards and mice are all pretty much the same so one generic driver
is suitable whereas the USB sound will be dependent on the codec chip
the manufacturer decided to use and thus would require a dedicated driver
to access the required registers to make it work.

I could be wrong though but the fact that ALSA is not included, I don't hold
out much hope that the Pi will be making any sounds as is.

[humblesoul]

Agreed, but if one is spending less than twenty quid on a computer... usb sound can be had for less than a fiver and is bound to be pretty generic at that price. Even some supposedly pro usb audio gear doesn't require drivers in windoze.

[Dave_G]

True, it all depends if any USB sound support is included in the distros
available for the Pi.
If so then theoretically one might find one (or more) USB sound adaptors
that may just work.

[sickgut]

*puff* *puff* phewww....
just catching my breathe, had a thought and came running down the mountain, i hope they put a road in so i can use a skateboard next time.

Any way, i have messed with a USB sound adaptor, its a budget behringer brand, but the interesting thing is that it works immediately in puppy 4.2, debian lenny/ squeeze and ubuntu and puppeee/ fluppy and others and windows xp with no looking around for drivers, its identified as a Generic USB sound device, aparently the hardware in these devices arent all the same but they use the same driver.... i think much the same way as external usb dvd drives and usb thumb drives all use the same set of generic drivers.

but i think most arm devices have never been made to attach usb sound devices too.... i dunno..... i would be interested if someone tests a cheapo $9 usb sound adator on one of these things.... is alsa installed at all in the software or is it there but not functioning?

[Dave_G]

sickgut wrote:

is alsa installed at all in the software or is it there but not functioning?

Judging from what Lobster wrote, I suspect that you may be heading back to the mountain very soon.
You may well be right that the generic USB Audio class driver
may not be available for ARM.

Lobster, any chance you have one of these USB audio goodies laying about
that you could try out and save sickgut the exhausting trip back up the mountain?
(The poor guy has a backpack full of mouthwash bottles, very heavy).

[prehistoric]

A video I saw via BBC showed the RPi connected to a television via HDMI. Normally, HDMI carries both digital video and digital sound. Could the assumption that people will use a television with HDMI be the key to this audio omission mystery? Generic USB audio should be a cheap alternative, but not particularly neat.

Very glad to hear that the dd problem was due to using /dev/sda1 instead of /dev/sda. You don't want to get into kernel debuggery on a system which does mysterious things with dd. I have an early netbook with a cheap SSD that looks like /dev/sda at boot and /dev/sdb later. Using dd on that is dangerous.

Been there on the powered USB hub mysteries. Another version of the problem shows up on devices like KVM switches which draw power from PS/2 ports.

Very general advice: even though you intend to squeeze your resulting system into a small SD card, use a large size, or an external USB drive, during development. (I also use unreasonably large swap partitions, so I can watch memory leaks develop before they bring a system down. Years ago this allowed me to trace a problem to a proprietary nVidia driver.) This would immediately distinguish between a restriction caused by the size of the card, and an entirely different restriction, as described above.

[Aitch]

The Pi has an HDMI combined digital video and audio o/p, as well as phono analogue video and 3.5mm audio o/p, so it IS designed for audio, and SBMC are interested as it has xbox/1080p video capabilities, apparently...so I suspect a codec issue only....there was talk of AAC licensing costs early on

http://forum.xbmc.org/showthread.php?tid=121499

Best get some skates on or XBMC will steal the glory!

Aitch

[Dave_G]

The drivers are one thing, whether they be USB, HDMI or thru the Pi's audio port.

The fact that Lobster mentioned that there is no ALSA, there is no way to "talk" to the drivers as there is no audio "core".

The way I see the Linux audio system is as follows: (could be wrong)

Code: Select all

{audio file} ----> {music app} ----> {ALSA} ----> {driver} ----> {hardware} ----> {audio out}

Hope I'm mistaken and that one of those USB thingies work.

[Lobster]

Barrys back proving that I am devolving . . .
No surprise there
http://bkhome.org/blog/?viewDetailed=02795

In other sound related news: Sound is not a priority for me. I may try my USB headphones which may have an inbuilt sound card - doubt it. Still wrestling with basic command line mayhem such as setting file permissions. Debian Squeeze for Rpi seems very much a work in progress. It will get you going for sure.

Slowly things are settling and I am making sense of the strengths and limitations of my understanding as well as hardware and software.

For those helping and wandering up and down mountains. I am reading and taking my time.

Here is something to get you riled up.
No Flash support.

OK time to continue . . .

[Aitch]

We are in this list already......

http://elinux.org/RPi_Distributions

....and Arch for Pi is CLI...apparently

http://news.techeye.net/hardware/linux- ... -available

Aitch

[sickgut]

The drivers are one thing, whether they be USB, HDMI or thru the Pi's audio port.

The fact that Lobster mentioned that there is no ALSA, there is no way to "talk" to the drivers as there is no audio "core".

The way I see the Linux audio system is as follows: (could be wrong)

Code: Select all

{audio file} ----> {music app} ----> {ALSA} ----> {driver} ----> {hardware} ----> {audio out}

Hope I'm mistaken and that one of those USB thingies work.

sorry to break from the current sound subject.
I want to ask people about clusters because altho the cpu in the Rasp Pi is lame, the video chip is very good, also 256mb ram is quite good also, altho the ethernet isnt gigabit, a gigabit ethernet adaptor could be used on the usb port. Is the usb port version 2.0? i hope it is.

new supercomputers are just clusters but the new ones also have the mechanizm to access GPUs to add to the processing capability just like a normal CPU, so a typical "blade" has 2x cpus on one motherboard and one high end video chip that adds a huge performance increase over just accessing cpus as processing power.

Is anyone here familiar with setting up clusters, and if so is it a simple affair to use attached gpus for processing power, is that a default option in the OS that lets you do this, or is this something very special and out of the reach of normal people?

The appeal of running alot of Rasp Pi in one huge cluster is no need to spend alot of money on cooling, and space is saved as well as power consumption. If the software is ready to access the gpu of the rasp to add this to the pool of processing power, it could actually be reasonably ok, not realy as a price perforamance thing but more like power consumption and maybe space and the ease of adding more "blades" later on and in the event of a failed "blade" its very simple to replace and inexpensive. The cost of a huge air conditioning system is saved and so is the maintanence on alot of water cooling compared to using high end cpus and or cpu fans. Ofcause with so many rasp pi crammed together the heat problem is more than a single rasp standing by itself, but i suspect just one large air forced fan blowing over 30 of them will be enough to keep the air circulating.

anyway.... if anyone knows about clusters accessing gpus then let me know

[Dave_G]

sickgut

I now nothing about clusters, just thinking out aloud here.
Presumably how clustering works is the processing cycles are distributed
amongst many CPUs/GPUs.

If this is indeed the case, then there must be some kind of high speed interconnecting "channel/s"
between the CPU's/GPU's to distribute and collect the data once it's been "crunched".
Surely even USB 2.0 at 480Mbps would create a bottle neck once a cluster
of a certain size has been exceeded?

Just a thought.

[sickgut]

sickgut

I now nothing about clusters, just thinking out aloud here.
Presumably how clustering works is the processing cycles are distributed
amongst many CPUs/GPUs.

If this is indeed the case, then there must be some kind of high speed interconnecting "channel/s"
between the CPU's/GPU's to distribute and collect the data once it's been "crunched".
Surely even USB 2.0 at 480Mbps would create a bottle neck once a cluster
of a certain size has been exceeded?

Just a thought.

i think the inability of the rasp pi to actually pump out processed data at 480Mbs a second would mean it isnt much of an issue as a bottle neck.. dont quote me tho.. just spitting out loud aswell. but yeah... unless we have good networking, you might as well thow it all in the bin. I need to research how much bandwidth is actually used in a gigabit cluster 480Mbs is almost half that speed... my instincts tell me the bottle neck would still be the rasp pi slow processing power...

i have placed an order for one but depending on what i can prioritize here at home, maybe ill order 10 of them just for giggles and try it all out. If it doesnt work out then i can give most of them away as presents to people who would like to have one.

i really do see the Rasp Pi as the perfect platform to bring linux gaming in a semi console format to the masses, but ofcause its not going to go anywhere without any sound how it is now.