Access serial port for data sent from Nios II's uart for real time plotting graph in Matlab

Hi all,

I am able to read data from FPGA to Nios processor, then transmit this data to Uart component created in Qsys using direct register method (IORD_ALTERA_AVALON_UART_STATUS (UART_BASE); IOWR_ALTERA_AVALON_UART_TXDATA(UART_BASE, txdata);etc).

Then, I was trying to access serial port data sent from uart in Altera Nios II to plot graph real time in Matlab. I was using this code from Matlab central (<http://uk.mathworks.com/matlabcentral/fileexchange/28941-real-time-data-plot-from-serial-port>) with minor modification as pasted below:

When I run this code I keep getting the following error. What should I do ?

??? In an assignment A(I) = B, the number of elements in B and I must be the same.

Error in ==> real_time_data_serial at 80 voltage(count) = fscanf(s,'%f');

I found a few solutions on the web, what I have tried: 1. add pause in .m file so that it has enough time to read the data before the next cycle of data

2. add enough delay at C code where I transmit data to uart

3. make sure the uart has the same setting as comport such as comport number, baud rate, parity, flow control

%%real time data plot from a serial port % This matlab script is for ploting a graph by accessing serial port data in % real time. Change the com values and all variable values accroding to % your requirements. Dont forget to add terminator in to your serial device program. % This script can be modified to be used on any platform by changing the % serialPort variable. % Author: Moidu thavot.

%%Clear all variables

clear all; %%Variables (Edit yourself)

SerialPort='com8'; %serial port MaxDeviation = 3;%Maximum Allowable Change from one value to next TimeInterval=0.2;%time interval between each input.0.2 loop=120;%count values %%Set up the serial port object s=serial('com8'); set(s,'BaudRate',9600,'DataBits', 8, 'Parity', 'none','StopBits', 1, 'FlowControl', 'none','Terminator','LF'); set(s, 'terminator', 'LF'); set(s, 'timeout', 10);

%%s = serial(SerialPort) fopen(s);

time =now; voltage = 0; %% Set up the figure figureHandle = figure('NumberTitle','off',... 'Name','Voltage Characteristics',... 'Color',[0 0 0],'Visible','off');

% Set axes axesHandle = axes('Parent',figureHandle,... 'YGrid','on',... 'YColor',[0.9725 0.9725 0.9725],... 'XGrid','on',... 'XColor',[0.9725 0.9725 0.9725],... 'Color',[0 0 0]);

hold on;

plotHandle = plot(axesHandle,time,voltage,'Marker','.','LineWidth',1,'Color',[0 1 0]);

xlim(axesHandle,[min(time) max(time+0.001)]);

% Create xlabel xlabel('Time','FontWeight','bold','FontSize',14,'Color',[1 1 0]);

% Create ylabel ylabel('Voltage in V','FontWeight','bold','FontSize',14,'Color',[1 1 0]);

% Create title title('Real Time Data','FontSize',15,'Color',[1 1 0]);

%% Initializing variables

voltage(1)=0; time(1)=0; count = 2; k=1; while ~isequal(count,loop)

    %%Re creating Serial port before timeout

    k=k+1;  
    if k==25
        fclose(s);
delete(s);
clear s;        
s = serial('com8');
fopen(s)
k=0;
    end

    %%Serial data accessing 
   pause(2);
   fprintf('here');
     voltage(count) = fscanf(s,'%f');

     %%For reducing Error Use your own costant

     voltage(1)=0;     
     if (voltage(count)-voltage(count-1)>MaxDeviation)
         voltage(count)=voltage(count-1);
     end

     time(count) = count;
    set(plotHandle,'YData',voltage,'XData',time);
    set(figureHandle,'Visible','on');
    datetick('x','mm/DD HH:MM');

    pause(5);
    count = count +1;
end

%% Clean up the serial port fclose(s); delete(s); clear s;

When I check the serial port status, I got the following:

Communication Settings Port: COM8 BaudRate: 9600 Terminator: 'LF'

   Communication State 
      Status:             open
      RecordStatus:       off

   Read/Write State  
      TransferStatus:     idle
      BytesAvailable:     0
      ValuesReceived:     0
      ValuesSent:         0

I noticed the serial port is ready (since it is open) but no data is sent or receive. Could you please tell me what is wrong so I could try?

Please , thank you

Answer 1

[want2know]

anyone please?