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Receiving data

To read data from the DSP, a read channel must be set up. This is done using the invoke open command with an 'R' parameter. invoke(h,'Open','ochan','R'); Reading data from the DSP board is a little more complicated. It seems that the DSP board buffers all the data. To get the latest piece of data, you must first 'Seek' to the current message. [status,nummsgs] = invoke(h,'GetNumMsgs');status = invoke(h,'Seek',nummsgs); Once at the correct message, the actual reading can be done. [status, values] = invoke(h,'ReadI2'); As with writing, the port should be closed after reading.

Using matlab gui features

MATLAB has some nice Graphical User Interface (GUI) features which can be used to control the flow of data to and from the RTDX port. The basic implementation consists of a blank window (figure) which can have differentinterface elements placed on it. These elements can be sliders, buttons, text boxes, etc...

When an element is accessed (for instance, a slider is moved, or a button is pushed), MATLAB will execute a "callback routine" which is a MATLAB function defined by the user. Desgining these interfacesis simple.

Creating a user interface with sliders

1 % rtdx_sliders - initializes RTDX port and sets up three sliders 23 h = actxserver('RTDX'); 45 % open a blank figure for the slider 6 Fig = figure(1);7 % open sliders 8 % first slider9 sld1 = uicontrol(Fig,'units','normal','pos',[.2,.7,.5,.05],...10 'style','slider','value',4,'max',254,'min',0,'callback','rtdx_wrt_sliders'); 1112 % second slider 13 sld2 = uicontrol(Fig,'units','normal','pos',[.2,.5,.5,.05],... 14 'style','slider','value',4,'max',254,'min',0,'callback','rtdx_wrt_sliders');15 16 % third slider17 sld3 = uicontrol(Fig,'units','normal','pos',[.2,.3,.5,.05],...18 'style','slider','value',4,'max',254,'min',0,'callback','rtdx_wrt_sliders');
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Lines 9 through the end create the three sliders for the user interface. Several parameters are used to specify the behavior of each slider. The first parameter,Fig, tells the slider to create itself in the window we created in Line 6. The rest of the parameters are property/value pairs:

  • units : Normal tells Matlab to use positioning relative to the window boundaries.
  • pos : Tells Matlab where to place the control.
  • style : Tells Matlab what type of control to place. slider creates a slider control.
  • value : Tells Matlab the default value for the control.
  • max : Tells Matlab the maximum value for the control.
  • min : Tells Matlab the maximum value for the control.
  • callback : Tells Matlab what script to call when the control is manipulated. rtdx_wrt_sliders is a Matlab file that writes the values of the controls to the RTDX port.
Every time a slider is moved, the rtdx_wrt_sliders.m file is called:

1 % rtdx_wrt_sliders : writes values of sliders out to rtdx 23 % open rtdx port for data transfer 4 status = invoke(h,'Open','ichan','W');5 6 % send valuefrom sld1 7 v1 = round(get(sld1,'value'));8 status = invoke(h,'Write',int16(v1)); 910 % send value from sld2 11 v2 = round(get(sld2,'value'));12 status = invoke(h,'Write',int16(v2)); 1314 % send value from sld3 15 v3 = round(get(sld3,'value'));16 status = invoke(h,'Write',int16(v3)); 1718 % send reset pulse 19 status = invoke(h,'Write',int16(2989));20 21 % close rtdx port22 status = invoke(h,'Close');
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Line 7 retrieves the value from the slider using the get function to retrieve the value property. The value is then rounded off to create an integer, and the integeris sent as an 16-bit quantity to the DSP in Line 8. The other two sliders are sent in the same way. Line 19 sends 2989 to the DSP, which can be used toindicate that the three previously-transmitted values represent a complete set of data points. ( You can use whatever value you want. ) This can be used to prevent the DSP and Matlab from losing synchronization if a transmittedcharacter is not received by the DSP and provides some error detection.

Line 22 closes the RTDX port. Make sure you close the port after sending a data block to the DSP.

Advanced features

The slider example shows some basic features of the gui tools. The handle for the RTDX server is generated into the workspace so that it can be used for writing. But other elements, such as text boxescannot be dealt with as easily. The Parameters from these can be accessed through their returned handles. Some examples:

%GUI.m %****Sample GUI, Text and a Button***%open a blank figure Fig = figure(1);set(Fig,'Name','Test GUI'); %Space to enter texted2 = uicontrol(Fig,'backgroundcolor','white','units','Normalized','pos',[.1,.6,.4,.05],...'string','Default Text','style','edit'); %Buttonbut1 = uicontrol(Fig,'foregroundcolor','blue','units','Normalized','pos',[.1,.4,.5,.1],...'string','Press Me!','style','pushbutton','callback','SampleGUI');

A Text box is created with default text in it that says: "Defaul Text". A button is also created, which when pressed, will execute the callback function SampleGUI.m

%SampleGUI.m %Get TexttestText = get(ed2,'string')

Now testText holds whatever string was entered into the text box. The function get() is used to retrieve the data from the 'string; parameter in the ed2 handle. MATLAB help uicontrol gives the full list of options for interface elements.

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Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
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Source:  OpenStax, Digital signal processing laboratory (ece 420 55x). OpenStax CNX. Jan 18, 2010 Download for free at http://cnx.org/content/col10397/1.10
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