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USB connection



The USB cable supplied with the amBX unit is an A-B type and is approximately 1.5 metres long. This may be too short, especially if you are connecting multiple units to the PC. The total length of a USB2 cable (or combination of cables) should be no more than 5m. If longer than this, it could have a detrimental effect and whatever is connected to the cable might not work properly.


As long as you don’t want a total length of more than 5m, you can either replace the supplied cable with a longer cable, or use the existing cable with a M-F extension cable no longer than 3.5m.


It is important that you use quality USB2 cables if you are extending or using a different cable to that supplied. Older USB1 cables are generally not made to such high specifications as USB2 cables and their recommended maximum length is shorter. If, like me, you have accumulated a collection of USB cables over the years, it is likely that many of these will be the older USB1 type. Unfortunately, it is almost impossible to identify whether a cable is USB1.1 or USB2 as there are normally no markings on the cable. (If I buy a USB2 cable, I mark it with a “2” for later identification). Depending on the length and the equipment connected to it, you may find that a USB1 cable works OK on some equipment. However, for best results, and if you are using long cables, make sure you use USB2 cables. Unless a USB cable or connector is labelled on the item or packaging, assume it is only USB1


If you have a cable that is 5m long or less and you are having problems with amBX, it may be that you need to replace the cable with a known USB2 one.



Running out of USB sockets?
The Philips amBX system uses one USB socket per system (for the wallwasher). The Madcatz Cyborg lights use one USB socket for each light – two sockets per set of lights.

Newer PCs may have as many as twelve USB sockets available, others may have four, a laptop may have only two. Some of these sockets are probably already in use, especially if you have a USB keyboard and mouse. If you are short of sockets, there are different options you can do:

1) If you have a PC with less than 12 USB sockets, it may be possible to add more sockets if the motherboard supports this. See your motherboard manual. Some of the motherboards have additional USB outlets on the motherboard that are unused – these are rows of pins that need a matching connector. You can buy USB panels containing USB sockets that fit onto the front of an empty drive bay. These usually have a connector that fits onto the motherboard USB outlet. This will give you up to four additional sockets on the front of the PC.

2) You can buy a USB card that fits into one of the vacant slots on the motherboard and can provide you with 2, 4 or more USB sockets at the back of the PC. Make sure you get the right card for the slot.

3) The simplest and easiest way, and one that doesn’t involve taking the PC apart – buy a hub.
This is also probably the cheapest way of all, unless you actually want the extra sockets on the PC.
A hub connects to a spare USB socket and can contain many USB sockets. The most common are four or eight port hubs, but others are available.



Do you need more than 5m?

If you need longer than 5m of cable between the PC and the unit, then there are still ways that you can do this:


USB repeater cable

Sometimes called active cables, USB2 repeater cables connect to the PC. They are normally 5m long and boost the signals. You can then connect up to 5m of USB2 cable between the repeater and the unit. It is generally recommended that you don’t use more than three repeater cables in one length (although some people say it’s OK to have five, but I expect it depends on what you have connected at the end). Experience has taught me that a maximum of three applies when connecting the unit. However, three repeaters at 5m each, plus one 5m A-D cable, could give you a total length of 20m between the PC and the unit. This is probably more than enough for most requirements.



USB hubs

A hub is a similar principle to a multi socket mains extension cable. A hub can have any amount of USB sockets (or ports) and connects to the PC via a single USB cable, effectively letting you connect several USB devices to one socket. They are usually used as a means of providing more USB ports to the PC or laptop. If using a hub, make sure you use a USB2 one. The most common types available have either four or seven ports.


Most hubs can also be used as a repeater and these are an ideal solution if you want to run more than one unit (or anything else) at the end of a long run of cable. Substitute the USB repeater cable with an ordinary USB cable connected to the hub. Generally, the same principle applies as when using USB repeater cables. You can “mix and match” USB repeaters and hubs on a cable run, although it is best not to use no more than a total of three. This will still give you a total run of 20m from PC to device. Devices can be connected to any hub used, as long as each device uses no more than 5m of cable. (Using more hubs / repeaters may work, but there is more chance of amBX not working properly).

If using more than one hub on a cable run, only the last hub (the one the devices are connected to) should be unpowered in order to avoid any potential problems. Any intermediate hubs should be powered. Ideally, power all hubs if you are connecting several devices.



Note

Some hubs, especially cheap ones you can pick up in the £ shops may not work correctly. They may not be suitable as repeaters, or they may not be USB2. If you’re buying a new hub, it’s preferable to buy a powered one (see below).


Powered hubs

A USB port can only supply 500mA of current. Therefore, the amount of devices that can be connected via hubs etc. to a single PC USB port will be limited by the total amount of current that they use. The hub also uses some current. Some devices, such as external USB drives, that do not have their own power supply, may require as much as the maximum 500mA. If they are having to share this current with other devices, they, or some of the other devices may not work properly. An unpowered hub will only supply a maximum of 100mA per socket. This is sometimes the reason (there are others) that you may see on a device’s instructions stating that it must be connected directly to the PC.


One way around this limitation, is to give the hub its own power supply. The hub then becomes a powered hub and can supply up to the maximum 500mA to each socket.

Note - the actual power available, may depend on the rating of the hub’s PSU - always check. I’ve used a 7 port USB2 Plexus hub during the amBX testing and that has a power supply rated at 2600mA which would normally be sufficient because even if I connect seven devices to the hub, it’s unlikely that they’ll all want the maximum power available. Many devices only require a small amount of current.


If buying a new hub, it’s always worth paying the extra and getting a powered hub, even if you don’t think you need the power. There may be a time in the future that you want to connect a device that needs more power, and this will save you having to buy a new hub.

I think everybody should have at least one powered hub as this can be used as part of the troubleshooting of failed connections. If you have several devices (or even one using more than 100mA) connected to an unpowered hub and you have problems with connections, devices on the hub not working properly etc., replacing the unpowered hub with a powered one can eliminate overloading the unpowered hub as the problem. If everything works when they are connected to the powered hub, it probably means that the unpowered hub was insufficient. It’s really a process of elimination and can save a lot of unnecessary wasted time when trying to diagnose when something doesn’t work.



Cat5 USB extender

These allow the signal to be send over Cat5e network cable.

They consist of a Transmitter which plugs into the PC USB port and a Receiver which has a USB socket on the end. The transmitter and receiver have network sockets on them so that a suitable length of network cable can be used to join the two together. The data from the USB port is suitable converted at the transmitter and sent along the cable to the receiver where it is converted back again ready for the USB device. This allows a much greater length of cable to be used between the PC and the USB device.


NOTE
Although the extension is made using network cable, the light is not a network device and the connection MUST NOT be made via a network router / hub / switch etc., only via the dedicated network cable.


Although I’ve tried three different versions, they’ve been USB1.1 or USB2 compatible. I think full USB2 versions are available, but at a much higher cost.


I’ve had mixed results using these with the wallwasher and, whilst the extension is longer than the maximum 5m USB, it doesn’t work on very long runs. On the Cyborg lights, a much longer network cable could be used. This is probably because the USB has to supply a lot of information to the wallwasher than it does to the one Cyborg light, so the timing might be more rigid for the wallwasher.



How many devices can you connect?

The USB sockets are controlled via a USB controller. A PC may have several controllers. Up to 127 devices can be connected to a controller. This means that, in theory at least, up to 127 USB devices can be connected together via hubs and one single cable to a USB socket on the PC. In practice, there would be limitations on this - not least the amount of powered hubs that would be required and the spaghetti junction of cables!

As part of the amBX testing, I had eleven Philips units connected via two hubs and one USB cable to the PC and all worked OK.


Hubs can be “daisy-chained” or branched as required, subject to the maximum cable length and power limits.

If you had six USB sockets on a PC and you connected a seven port hub to each of these sockets, that would give you 42 USB sockets available for use. If you daisy-chained three powered seven port hubs together, that would give you 19 ports altogether (6 on the first, 6 on the second and 7 on the third) connected to the one socket on the PC. You could also branch off with more hubs connected to the first and second hubs, and so on, up to the maximum.



























Fig. U1:  Examples of various ways to connect devices to a single USB port


1  has one device at the end of 20m cable, using three repeaters

2  has one device at the end of 20m cable using two repeaters and one hub. Further devices can be added at the hub

3  has one device at the end of 20m cable using one hub and two repeaters, plus one device at the hub. More can be added

4  has nine devices connected via four hubs. More can be added


for more detailed information about USB and USB hubs, see the following Wikipedia pages:

http://en.wikipedia.org/wiki/Universal_Serial_Bus

http://en.wikipedia.org/wiki/USB_hub



Testing different amBX setups

I’ve been lucky that I’ve been able to borrow some extra units to play with as well as my own and at one point I was able to connect eleven units up at once - a good way to test the amBX system and USB connections.


Armed with two powered Plexus 7 port USB2 hubs (Plex-039), some Plexus 5m USB2 repeater cables and various 5m Belkin USB2 A-A and A-D cables, I was able to try out a wide permutation of units and cable connections, some of which are shown below. Generally, I found that it didn’t matter if I used a 5m repeater cable or a hub at the end of a 5m cable (the hub acting as a repeater), the results were the same.


I used a PC with an AMD3000 processor which, these days, may be thought of as a little slow, running XP. I’d only done a re-install of XP a few months ago, and hadn’t got much loaded on it and so the PC was quite clean with nothing that could adversely affect amBX working.


To test the setup, I used scenes from the DirectControl panel and the Aurora, Illuminate and Synthesizer modes in Aurora Synesthesia v1.06  (AS). In all tests, if there were going to be any problems, the PC usually crashed when I started a scene etc. or shortly afterwards. I found that if everything was working after five minutes, it would continue to do so, whatever mode I was using. I use the term “crash” loosely. I suspect in some cases that it had slowed to an extreme crawl, rather than actually crashed, but the effect was the same and it meant a reboot of the PC to get everything running again.


To show some of the tests that I did, these are from edited postings about the tests that I put in a thread on the amBX forum:


I’ve dug up some extension leads and had a play around. I set up amBX units as follows:
One unit direct to it’s own USB port on the computer via the supplied 1.5m lead. This worked perfectly all the time, so I won’t mention this unit again.

Six units to the Plexus hub, each via their own 1.5m cable. I didn’t bother to power the hub. I then added all the USB cables to effectively make a long cable between the computer and the hub. The length of the cable shown below is the total length between the computer and the hub, plus the 1.5m between the hub and a unit. I opened up the Philips DirectControl panel to check the icons:


22.5m - Nothing. Hub not recognised, units not recognised
19.5m - Hub recognised. Device errors at hub for units
16.5m - Hub recognised. Device errors at hub for units
13.5m - Hub recognised. All six units recognised. Played around switching between scenes. Crashed
11.5m - Hub recognised. All six units recognised. Played around switching between scenes. Crashed
8.5m - This is my present setup (7m between computer and hub, 1.5m between hub and unit). Everything worked as it should do, including Aurora screen effects in Media Player Classic, and Aurora audio effects.

5m + 2 x 5m repeater cables to hub + 1.5m to unit (16.5m). All worked normally
5m + 3 x 5m repeater cables to hub + 1.5m to unit (21.5m). Only three out of six units recognised. These worked normally
I rebooted the computer and tried the same setup with the three repeater cables again and this time I got an “Incorrect amBX firmware detected” message.  I assume that this is because it’s not detecting a unit properly (the firmware). Only one unit was detected this time, then it crashed. I rebooted the computer and tried the two repeater setup again just to prove it was all working OK and it was.
It’s quite likely that if I reduced the total length of the ordinary 5m cable to around 2 – 3m, then using the three repeater cables would have worked, giving a total cable length of around 19 – 20m
Reading the above now, I suspect that the problem with the 5m + 3 x 5m repeater cables to hub + 1.5m setup was that, with the hub, there were effectively four repeaters in the cable run and it didn’t like it. Also, the hub wasn’t powered, although I don’t know if that would have made a difference or not.


As the results show, whilst there is a bit of leeway if using over the total recommended 5m length of cable, it’s not very forgiving the longer the cable is. Using active / repeater extension USB cables is the only way to extend the USB connection (the repeater cable should be plugged into the computer, the ordinary USB cable connects between the repeater and the hub or direct to the unit).


next post:

Since my post yesterday, I decided to look at the Wikipedia USB entry as I wanted to see the total power that a USB port could output. I found an entry regarding cable lengths and one thing that I didn’t know was that it appeared that hubs could act as a repeater. I decided to investigate and tried the following configurations, working in the DirectControl and Aurora in Ambient mode as with yesterdays tests:

1st configuration
Hub 1 had five units connected to it and was connected to the computer via the standard 5m cable. Hub 2 was connected to a port on hub 1 via a 5m cable. Hub 2 had 1 unit connected. Hub 2 was at the end of the chain. The hubs were not powered.
The unit on hub 2 wasn’t recognised – no light for that port on the hub. The five units on hub 1 were recognised in the panel and the scenes worked.
I connected the hub PSU to hub 1 and rebooted. All units recognised and worked OK on test

2nd configuration
Hub2 (one unit) was connected to the PC via the 5m cable and left unpowered. Hub1 (5 units) was connected to hub 2. Hub 1 was still powered, and was at the end of the chain. This time all six units were recognised
All units detected, but there were problems. Rebooted with hub 2 now powered as well and everything tested OK

3rd configuration
5m repeater cable connected between PC and hub 2, hub 1 connected to hub 2. Hub 1, with five units connected was at the end of the chain and both hubs were powered. Total cable length = 15m, plus the two metre cables between each unit and the hub.

Therefore, it seems that the hubs do indeed act as repeaters. However, mine needed to be powered to work properly. So, dependent on hub, it would seem that a hub may only act as a repeater if it is powered. This may not be the same in all instances and it may be that some non-powered hubs work as repeaters and some powered hubs don’t. It may be a case of trial and error. Actual maximum cable length may also be affected by the quality of the cable used.

Both hubs = Plexus. Cables, other than the 1.5m unit cable supplied, are Belkin






























Fig. U2:  The three configurations





Next post

Well I connected up eleven units in two configurations as shown below. The cable between the hub and PC and between hubs was 5m long, the cables to each of the units were the supplied 1.5m cables.

All the units worked OK, although I was surprised that I got away with not powering up hub1 on test 2. When I've done any tests, I've normally only used the music side, not games (I haven't got any) or the screen effects. I've been running it in the test 2 setup for about 2 hours now, whilst using the computer for a few other things and everything's been working OK. I’m currently running Aurora with the Aurora part disabled and playing a variety of tracks via the line in on the PC.


I’ve also tried the same test 2 setup (using Aurora) on a Compaq laptop which, according to My Computer has the following CPU:
Intel Pentium dual CPU T2310@1.46GHz 1.47GHz, which I assume is slower than my AMD 3000 (it certainly seems it) and all works fine on there as well.















Fig U3: Connecting eleven units to one USB port




So, from the tests that I did, I’ve reached the conclusion that, for the Philips units, as long as the 5m cable length between PC / repeater / hub / unit is not exceeded and there are no more than three repeaters / hubs in the total cable length, then everything should work OK, irrespective of the amount of units connected. Any hubs may need to be powered.


I’ve not done as many tests using the Cyborg lights. The comments above should apply to the Cyborg lights as well, and it may be possible to increase the amount of repeaters / hubs to four. However, if you need long extensions, it might be better to use Cat5 USB extenders. See the Madcatz pages for more details.