Tascam US-224

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http://www.tascam.com/Products/US-224/us224_frontFP.jpg

\ The Tascam US-224 is an external USB audio device which sports the following features:

The Tascam US-224 is well supported under Alsa, but it can be tricky to get it running at its maximum potential. Hopefully after reading this document you will be able to:

Contents

The ingredients

In order to make your US-224 work under linux you will need:

You could also use the external alsa drivers instead of those included with your kernel version, even if with a modern kernel there are no real reasons to do so.

To make your life easier you should also make sure that the lsusb command, from the 'usbutils' package, is available on your system. It will allow you to easily identify the resources used by your card without poking inside /proc.

Maybe it 'Just Works'?

Chances are that your distribution has already set everything up for you, and the card is configured automatically when it is plugged in your PC. If the green led marked as 'USB' lights up a few seconds after the card is plugged in and turned on, you can safely skip the next section. Otherwise keep on reading.

Setting up your US-224 manually

We are now going to explain how to setup your US-224 manually. Please make sure your card is connected to a USB port and turned on. The green led named 'Power' should be on.

Kernel module

The first step is to make sure that the appropriate kernel module (which is known as the 'driver' in the Windows world) is available and loaded. The kernel module for the US-224 is called snd-usb-usx2y, and to make sure it is available on your system you can run the following command as root (from now on all commands will have to be run as root unless stated otherwise):

$ modprobe snd-usb-usx2y

If the module is available it will be loaded silently, otherwise some kind of error message will be shown. If the module is not present you will have to recompile your kernel. You can find a lot of howtos which thoroughly explain this step (a good one can be found here). Make sure you select the snd-usb-usx2y module in the Alsa section of your kernel configuration, under 'USB devices'.

Once you have loaded the kernel module, it should show up when executing the lsmod command, whose output should contain lines similar to these ones:

$ lsmod
Module                  Size  Used by
[...]
snd_usb_usx2y          20160  0
[...]

Please note that hyphens are replaced by underscores in the output of lsmod.

Setting up firmware and FPGA

The kernel module is not enough to make the card work. The US-224 needs also a firmware and its FPGA must be programmed before use.

To load the firmware you will need the 'fxload' utility (as described above) and two firmware binary files. These files are included in the alsa-firmware package, and are are named tascam_loader.ihx and us224fw.ihx. They can typically be found in such locations as /usr/share/alsa/firmware/usx2yloader, /usr/local/share/alsa/firmware/usx2yloader, etc. Before loading the firmware you must find out which bus the card is attached to and which device number it has been assigned. The best way to gather this info is through the lsusb utility, from the 'usbutils' packages. Executing lsusb from the console will output something similar to this:

Bus 003 Device 008: ID 04b4:6830 Cypress Semiconductor Corp. USB-2.0 IDE Adapter
Bus 003 Device 001: ID 0000:0000
Bus 002 Device 007: ID 1604:8004 Tascam US-224 Audio/Midi Controller (without fw)
Bus 002 Device 006: ID 046d:c03d Logitech, Inc.
Bus 002 Device 001: ID 0000:0000
Bus 001 Device 001: ID 0000:0000

In this case the card is attached to Bus 002 and its device number is 007. As you can see lsusb recognizes that the card is without firmware.

Now we can upload the firmware to the card using the following command:

$ fxload  -s /usr/share/alsa/firmware/usx2yloader/tascam_loader.ihx \
  -I /usr/share/alsa/firmware/usx2yloader/us224fw.ihx -D /proc/bus/usb/002/007

You will have to use the locations of the actual firmware files on your system, and the bus/device numbers your card is related to. Beware that they are not static and they will change as you connect/disconnect USB devices.

You can check that the firmware has actually been loaded into the card by launching the lsusb command again. It should output something like this:

Bus 003 Device 008: ID 04b4:6830 Cypress Semiconductor Corp. USB-2.0 IDE Adapter
Bus 003 Device 001: ID 0000:0000
Bus 002 Device 008: ID 1604:8005 Tascam US-224 Audio/Midi Controller
Bus 002 Device 006: ID 046d:c03d Logitech, Inc.
Bus 002 Device 001: ID 0000:0000
Bus 001 Device 001: ID 0000:0000

As you can see the card's device number has increased by one and the (without fw) indication has disappeared.

As for the FPGA, it needs to be programmed before using the card. You can do this by simply launching the usx2yloader command, from the alsa-tools package:

$ usx2yloader

At this point after a couple of seconds the card's leds should blink, and the 'USB' green led should turn on. You may also hear a clicking sound if your speakers are connected to the card.

Starting us428control

'us428control' is a small program, available in the alsa-tools package, that sits in the background and manages the physical controls on your US-224. If you do not run it you may not be able to hear anything from the card because it is muted by default and there are no software mixers on the board. The only way to raise the volume is through the knobs and faders, and they are non functional until 'us428control' is running. You should launch us428control by appending &, so that it won't block your console while it is running:

$ us428control &

This command may output a message similar to

us428control: cannot open hwdep hw:0

This is perfectly fine if you have another card which is loaded before the US-224: us428control probes all cards beginning from the first one until it finds a Tascam card. If you want to get rid of this message you can explicitly tell us428control to probe just a specific device by using the -c switch.

Testing the card

To check whether the card is functional or not, run the following command, making sure that you are using the right value for the -D option (hw:0 is for the first soundcard, hw:1 for the second one and so on):

$ speaker-test -c2 -D hw:1 -twav

Make also sure that all the volume controls on the soundcard are not mutedĀ :)

Minimizing latency in JACK

In order to squeeze out the best performance in terms of latency with JACK you will have to tweak a bit the configuration of your US-224. The first step is to load the kernel module with the option nrpacks set to 1:

$ modprobe snd-usb-usx2y nrpacks=1

If you don't want to specify this parameter each time you load the module (and, most importantly, if you want this option to be picked up by your distribution's scripts automatically) you will have to modify a file, called /etc/modules.conf, by adding the following line somewhere:

options snd-usb-usx2y nrpacks=1

Caveat:some distributions use the file /etc/conf.modules in place of /etc/modules.conf, and some other distributions (e.g., Gentoo) use the more flexible approach of re-building /etc/modules.conf at each system startup from a group of files in the /etc/modules.d/ directory. Please consult your distribution's documentation for details regarding the management of /etc/modules.conf.


What does the nrpacks=1 option do? Basically it is a USB setting that enables lower latency transmission over the bus. This settings is detected by JACK, which features an experimental rawusb driver capable of exploiting this low latency route over the USB bus. Keep in mind that this driver is still experimental and may not work for you, but it is not dangerous to try it.

To enable the rawusb backend in JACK you have to start it specifying the Alsa sub-device number 2. For instance:

$ jackd -dalsa -dhw:1,2 <other JACK parameters follow>

This means that we are using jackd with the Alsa backend on the second card (numbered 1 because the first card is given number 0) and sub-device number 2. If you did not load snd-usb-usxy with the nrpacks=1 option, sub-device number 2 will not be available and JACK will exit with an error. If you are using qjackctl to start JACK, you can confirm that the nrpacks=1 setting has actually been used when loading the module by checking for the existence of the 'US-X2Y hwdep Audio' device when pressing the '>' button in the 'Setup' window of qjackctl:

File:Qjackctl rawusb.png

\

That said, you can reach the physical limits of low latency over USB also by using the standard JACK driver in conjunction with a realtime kernel and the rtirq script by Rui Nuno Capela. According to my personal experience, the US-224 works better with low values for the period length (-p parameter in JACK) and higher values for the number of periods (-n parameter in JACK), which somehow contradicts what is written in JACK's man pages. For instance with -p128 -n2 the sound comes out rather choppy, while with -p64 -n4 the sound has no distortions whatsoever. -p64 -n4 corresponds to a latency of 5.8ms, which, to my knowledge, is close to the best you can theoretically achieve over USB.

Using the control surface in Ardour

To use the control surface of your US-224 in Ardour you will need to:

To achieve the first goal we are going to assume that qjackctl is correctly installed on your system and that you are able to use it to start JACK.

Once JACK has been started with qjackctl and Ardour is running, click on the 'Connect' button on the main window of qjackctl, then select the 'MIDI' tab in the window that just popped up. You have to establish the following connections using drag&drop between the two panes:

File:Qjackctl tascam control surface.png

Here we are setting things up so that control events generated on the card will be reported to Ardour (so that, for instance, when you press the 'Play' button on the card Ardour will start playing), and conversely Ardour will report back to the card about control events generated inside Ardour itself (so that, for instance, if you press the 'Record' button in Ardour the card's 'Record' led will be powered on too). You can use qjackctl's patchbay functionality to store and recall JACK's connections in a file to avoid manually establishing them each time.

The second step is to enable control surface support in Ardour. To achieve this you have to check the following options under the 'Options' menu in Ardour's main window:

Additionally, you have to open the 'Options -> Option Editor' window, click on the 'MIDI' tab and make sure that all the available options for the control port are activated:

File:Ardour control options.png

\ At this point you should be able to use your US-224 to pilot Ardour. You can, for instance, play or start recording by pressing the card's button, as well as use the 'Locate' buttons and the jog wheel to change position of the cursor in Ardour's tracks. Some buttons, like the 'Null' and 'Solo' ones, are not yet supported as of March 2007 (us428control version 0.4.4). Support for these buttons is present in the upcoming versions (which will be included as usual in the alsa-tools package).

Troubleshooting

Q: The 'power' and 'USB' leds are turned on, the card is detected by the Alsa subsystem, volumes are unmuted but I can't hear any sound.

A: Probably you forgot to run the us428control utility, which activates the card's knobs, faders and switches. Run it in a console as root (possibly appending the & character to avoid killing it when you close the console):

$ us428control &

Q: All volumes are unmuted and us428control is running, but I can't hear any sound from the mic/guitar I've plugged in the card.

A: Make sure that you pressed the 'Input monitor' button and that the corresponding led is on. Input volumes can be adjusted using the first two faders.

Q: The card seems to hang at random times, and I get messages like

ep=8 stalled with status=-18

or

Sequence Error!(hcd_frame=5170779 ep=8in;wait=5170776,frame=5170777).

in the kernel logs.

A: Most likely you are running with some sort of power management activated. In particular this card seems very sensitive to the changes of CPU frequency. On my laptop, for instance, every time the CPU scales frequency the card hangs for a while. My suggestion is to disable CPU scaling altogether when you are using the card. On a modern linux distribution you can fix the CPU frequency to the highest value available with the following command:

$ echo "performance" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

You may want to experiment a bit and read about CPU frequency scaling. A good resource can be found here.

Q: The card is connected, the power led is on and the firmware has been successfully loaded, but us428control / usx2yloader fails with an error message similar to

no US-X2Y-compatible cards found

A: Check that us428control / usx2yloader is not already running.

See also

Retrieved from "http://alsa.opensrc.org/Tascam_US-224"

Category: Sound cards

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