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Programming Mini-Bee in Visual Basic |
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Although Mini-Bee comes with it's own
software (BeeStep14) to allow the beginner to start using it in home
automation projects very quickly, it also comes with a DLL interface to
allow the intermediate and advanced user to write their own programs for
it. The DLL provides a general purpose interface that greatly simplifies
the task of writing programs for a USB device. It can be tricky
manipulating the USB comms into sending and receiving messages to and from
a device which can easily be plugged and unplugged at any time. The
DLL eliminates all of these headaches by simplifying the task into two
library functions. |
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InitMbee( )
and
SetOutputs (outputs) |
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InitMbee() is called somewhere near the start of your program and
takes care of all of the USB comms initialisation and prepares the Mini-Bee
for receiving messages.
SetOutputs(outputs) can then be called at
any time during your program to set the output pattern of on's and off's.
The parameter Outputs is simply a 32 bit integer value where bit0
corresponds to output 1, bit 1 to output2, etc... Where a logic value of 1
turns the output on and a value of 0 turns it off. For example the
statement below would turn on the first three outputs... |
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SetOutputs (7) |
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The only other thing that a VB program
must do is to declare the functions that it is going to use within the DLL
and the name of the DLL itself. This must be done at the start of your
program or at least before any references to the two functions are made.
The following is an program excerpt showing how this is done... |
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Declare
Function
InitMbee Lib "mb.dll"
() As
Boolean
Declare
Function SetOutputs
Lib "mb.dll" (ByVal
outputs As
Integer)
As
Boolean |
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The first declaration states that the function InitMbee
has no parameters,
is found in mb.dll and returns a boolean value. The second states that
SetOutputs has one integer parameter passed by value rather than reference, is
found in mb.dll and also returns a boolean value. It should be
noted that the |
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Lib
"mb.dll" |
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lets the program know where to find the mb.dll file. When written like
this it assumes that since there is no path information that the
mb.dll
file can be found in the windows system directory
c:\windows\system32
If you like you can copy the file mb.dll on the installation disk to the
system32 directory and the above statement will work perfectly.
Alternatively you can copy the file to some other location and give that
location in the declaration as the example below shows ... |
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Declare
Function
InitMbee Lib
"c:\Mylibrary\mb.dll" () As
Boolean |
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To speed up your development of software for the Mini-Bee a complete working
example is available for download below. It is called VBmini and creates a
very simple form based program that has individual buttons for various
functions such as initialising the Mini-Bee and setting various patterns on
the outputs. The main (and only) screen is shown on the right. This
has been written using Microsoft Visual Studio .net and the download files
contain the full workspace (solution) details to allow you to
immediately open and start editing or running.
Even if you don't have Visual Studio, the source code is virtually
self explanatory with the most relevant sections being in "Form1.vb" which
can even be opened in a simple text editor such as notepad. The files are
zipped for convenience and may be downloaded by right clicking on the link
below and choosing "save target as" to begin the download. |
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Download Files |
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©
Copyright pc-control.co.uk 2008 |
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