After 12 months of intensive development work, we are now able to offer a Universal Serial
Bus 2.0 interface for use with any of our MX and HX series cameras. Unlike dedicated USB
interfaces, which can be used only with a specific device and cannot be updated with
improved software at a later date, the Starlight Xpress interface is fully re-programmable and
may be updated at any time.

For instance, if you currently own an HX516 camera and buy a USB interface to speed up the
download, the same interface can be used at a later date with your new MX7-C or MX916,
simply by downloading the free software from our web site! (N.B. Please note that the HX916
USB interface is different from that used with our other cameras and so is not transferable)

The USB interface kit:

Why USB?

Several kinds of camera to computer interfaces are currently used with astronomical CCD
systems, the PC serial and parallel ports being perhaps the most common. However, the
serial port is relatively slow and the parallel port needs a multicore cable, has various
compatibility issues and is not fitted to some modern laptops. Most other forms of interface
include some kind of plug-in card, many of which are not usable with laptops, or add
significant cost to the system. USB is probably the best way to overcome these problems, in
that it is widely available on all modern machines, uses a lightweight inexpensive cable, and
is
relatively fast. By careful assembly language programming of the hardware, a data download
link at about 8Mbits per second is possible and the result is seen as readout times of only
between 2 and 5 seconds for most Starlight cameras.

The USB programmable interface:

The use of a USB connection involves a relatively complex interface device at the remote unit,
as USB data is 'packeted' and uses the same wire pair for both transmit and receive. This
device may be in the form of a pre-programmed microprocessor chip, dedicated to a single
camera, or a fully re-programmable processor, which is loaded with the appropriate software
via the USB cable at switch-on, and so may be adapted to operate any camera. Starlight
Xpress have chosen this second course and our USB interface can be re-programmed at any
time for any Starlight camera.
Driver software updates may be downloaded from our web page, when available, and you may
interchange cameras without the additional cost of a new interface.

The camera driver software is contained in a 'hex' data file, which resides in the Windows
'System32\Drivers\' directory and when the interface is connected to the computer, a software
loader recognises it as an 'empty' USB device and downloads the hex file into its internal
memory. The USB interface then takes on its new identity as a driver for the camera being
used, until it is disconnected or switched off. Substituting a different hex file matches the
interface to whichever camera the file is written for.

Using the USB interface:

The following paragraphs describe the software installation and operation in more detail:

Installing the USB system:

The software files for the USB system are normally supplied in an 'Installshield' (TM)
self-installing format. Running the 'Setup.exe' file will invoke the necessary steps to copy the
files into their orrect directories and should give you no problems. However, in the case that
the software does not install correctly, or is damaged in some way, the information below
may
be of some assistance.

The USB cable has only 4 cores; 2 for data transfer and 2 for a low current 5 volts supply.
Data is sent in serial 'packets' at a clock speed of 12 megabits per second, allowing a
maximum data transfer rate of the order of 1,216,000 bytes per second in 'Bulk' mode. In
practice, there are other delays and commands being transferred that reduce the true
long-term rate, but still allow camera images to be sent at rates of 3 or 4 times faster than
the
parallel port. The USB specification gives the maximum cable length as 5 metres, but it can
be considerably longer than this, if of good quality. We have found that 15 metres is usually
practical and in-line repeaters may be used to extend this.

USB uses a simple cable, but relies on complex software to permit fast data transfers without
clashes. This requires a processor at both ends of the link and so USB devices always
contain a microcontroller chip, such as a clone of the Intel 8051. This also allows the USB
device to perform relatively complex operations independently of the PC, a fact that can be
very useful when controlling a CCD camera. However, the complex software at the PC end
does lead to a relatively difficult exercise in programming and can lead to installation
problems. Various forms of data transfer can be used with USB devices and are suited to
different functions. The SX USB interface uses 'HID' (Human Interface Device) control signals
to pass instructions from the PC to the interface and 'Block IO' transfers to send camera data
back to the PC. Block transfers are fast and have error correction built-in, so that the image
data is guaranteed to arrive in good condition. This duality of data transfer requires that the
interface is installed as a 'USB Composite Device' with both HID and BlockIO components -
more of this later.

In most USB devices, the USB microcontroller is programmed at manufacture and can
execute only one fixed program, but this is very restrictive, especially if you wish to upgrade
the software or use it to control a different camera. To avoid this major inconvenience, we
have
chosen to use a unique USB device from Cypress Semiconductors, which is fully
re-programmable via the USB connection. Whenever the interface is connected to the
computer, the PC software recognises the device and sends the required software to it,
reprogramming it to become whatever kind of interface is needed at the time!

This software uploading operation is automatic, but it is independent of the camera control
program and needs to be installed separately onto your computer, before the camera
software
can be used. The USB device software is stored in a data file named '05472131.hex', a
unique
name, which can be recognised by the software installer program 'LoadEz.sys'. A second
program, called 'BlockIO.sys', is used by the computer to transfer data from the operating
USB device into internal PC memory. LoadEz.sys and BlockIO.sys are the same for all
cameras, but 05472131.hex is different for each. If you intend to use more than one Starlight
Xpress USB camera with the same computer, you must keep the hex files in different
directories (e.g. 'MX5' and 'HX9' etc.) and swap them with the active file, as necessary.

Installing the USB system:

Your USB kit will contain the following hardware:

1) A USB driver module.
2) A 5 metre USB cable.
3) A 1.5 metre, 15 way camera lead.

Also included will be a disk of software needed to operate the system.

The USB interface will work with the following operating systems: Windows 98, Windows
Millennium and Windows 2000. Older versions of Windows and Windows NT, do not have
proper USB support.

First, find a free USB socket on your PC and plug in the USB cable, - do not connect it to the
USB interface box at this time. If you do not have a USB capable computer, it is normally
possible to install a USB card into an expansion slot. Almost all machines manufactured
after
1996 provide a pair of USB sockets on the rear panel and either of these may be used.
Please
note that it may be necessary to enable your USB system in the computer BIOS (the SETUP
menu which can usually be accessed at start-up). Many BIOS systems have the ability to
disable 'Plug and Play' devices, such as the USB ports, so please make sure that these are
enabled.

The next operation is to use Windows Explorer to copy the USB driver files into the
appropriate directories of your computer hard drive. The software will normally be in the form
of
an automatic installer, but, if not, please copy the files as follows:

1) Copy 'Empty.inf' and 'BlockIO.inf' to C:\Windows\Inf\
2) Copy '05472131.Hex', 'LoadEz.sys', 'Generic.sys' and 'BlockIO.sys' to
C:\Windows\System32\Drivers\
3) Copy 'Apigid32.dll' and the other dlls to C:\Windows\System\
4) Copy the main program 'exe' file and 'ini' file to your CCD directory.

If you cannot see the directories 'Windows\Inf' and 'Windows\System32\Drivers', this will be
due to the setup of your Windows Explorer software. In this case, go to the 'Tools' menu,
followed by 'Folder Options' and select 'View'. Now select 'Show hidden files and folders' and
make sure that the 'Hide file extensions for known file types' and 'Hide protected operating
system files' check boxes are NOT checked. After this, the various directories and files
should
be visible.

Running the software:

When using the USB system, the following power-up sequence should be observed.
Alternative sequences will do no damage, but may prevent the plug & play system from
recognising the interface.

First, connect the camera and interface with the 15 way 'D' connector lead. Now plug in the
power lead and switch on the power supply. Finally, plug the USB cable into the computer
and interface. (NB. If, for any reason, you need to 're-boot' the USB link, you MUST unplug
the
power lead to the camera and reconnect it after 5 seconds before plugging in the USB cable.
Otherwise, the interface will retain its previous version of internal software and fail to re-boot
properly.)

After a brief delay, you should see an information box, which reports that the computer is
'installing new hardware'. If all is well, the cycle should be repeated 3 times and you should
see various devices, such as 'USB composite device' and 'BlockIO composite device'
appearing in the info. box. All of these devices will be named 'Echo1'.

The sequence should complete without any need to interfere, but it is possible that Windows
may ask you to tell it where a driver is stored. If this happens, then you may need to select
the appropriate driver or inf file in C:\Windows\System32\Drivers or C:\Windows\Inf\.
Just follow the instructions on screen and highlight the correct file.

At the end of this process, the USB interface will be installed as a 'USB composite device'
and the camera software will be able to access it. You can confirm that the installation is
complete by checking the status of the USB devices in the Windows 'Device Manager'. Start
up the Windows 'Control Panel' and select 'System'. Now click on the tab labelled 'Device
Manager' and all of the system devices will be displayed in a list. If the installation is
successful, there will be a diamond shaped symbol labelled 'BlockIO' and clicking on the '+'
sign will reveal it to be an 'HIDwithBlockIO BlockIO device'. There should also be a 'USB
human interface device' under the 'Human interface devices' tag, and a 'USB composite
device'
under the 'Universal serial bus controllers' tag. If any of these devices is faulty, try clicking on
it and selecting 'properties' and then 'update driver'. Following the on screen instructions will
allow you to re-select the correct inf file and driver, which should fix the problem.

Now start the camera software by clicking on the icon, which should have appeared on your
computer desktop. It should start with a message that an 'HID' device and a 'BlockIO' device
have been found and will give 'Handle' values to each. If one or both interfaces fails to be
found,
try re-booting the USB interface by unplugging both the power lead and USB lead and then
reconnecting (power first). If this does not work, you may need to check that all the USB
drivers have installed correctly, as described above.

The software will now operate normally and your new interface should greatly accelerate the
download of images.

Typical USB readout times:

HX9 full resolution: 11-13 seconds, binned 2x2: 3-4 seconds

MX7C: 3-4 seconds

MX5/5C: 2-3 seconds

HX5 full resolution: 3-4 seconds, binned 2x2: 2-3 seconds, binned 3x3: 1 second

Functional restrictions of the USB system:

It is currently not possible to operate two Starlight USB cameras simultaneously from one
computer. The software uploader cannot distinguish between the interfaces and will try to
drive
them as one unit. It should, however, be possible to operate one camera via the parallel port
while a second is connected via USB. This will enable a separate guide camera to be used
with a USB camera.

We do not recommend the use of other USB devices at the same time as a Starlight USB
camera. The packet transfer can become disrupted during download and cause 'artefacts' in
the images.

Price - £190.00

The Astronomy Shop

1 Tone Hill. Wellington

Somerset TA21 0AU

United Kingdom

Telephone: +44 (0)1823 665510