close all;
clear all;

% file: com8001r1.M
% modified: 8-29-02
% Author: MSS/Alain Zarembowitch
% 
%--------------------
% Generates baseband signal for the COM-8001 pattern generator
% Format is 2 (complex) * 10-bit (unsigned).
% Signal is a sinewave at frequency fc.
%--------------------
fs = 200000;	   % sampling rate 200 KHz typ.
nsamples = 200;	% simulation duration, expressed as number of complex samples
fc = 1000;			% sinewave frequency in Hz
gain = 0.7			% prevent saturation at the D/A converter


% for long simulations, store results in output file
[fid_o1,message]  = fopen('com8001r1.bin','w');
if(fid_o1 == -1)
   message
end


% initialization
last_i = 0;
last_q = 0;
current_i = 0;
current_q = 0;
b = dec2bin(0,10);

%------------------------------------------------------
% MAIN LOOP
%------------------------------------------------------

% loop signal processing (cannot use vectors)
for j = 1:nsamples
	i = j   
   
   phase = 2.*pi*fc*(i-1)/fs;	% carrier phase
   carrier_cos = cos(phase);	
   carrier_sin = sin(phase);
   
   sigt1i = carrier_cos*gain;
   sigt1q = carrier_sin*gain;
   
   % convert samples to 10-bit unsigned format
   % (numbers are pretty much the same after this calculation)
   sigt2i = min(max((floor((sigt1i+1.)*511.5)),0.),1023);
   sigt2q = min(max((floor((sigt1q+1.)*511.5)),0.),1023);
   
   test1(i) = sigt1i;
   test2(i) = sigt1q;
     
   %invert bit order because of pinout
   a = dec2bin(sigt2i, 10);
   b(1) = a(10);
   b(2) = a(9);
   b(3) = a(8);
   b(4) = a(7);
   b(5) = a(6);
   b(6) = a(5);
   b(7) = a(4);
   b(8) = a(3);
   b(9) = a(2);
   b(10) = a(1);
   outputi = bin2dec(b);
   
   test5(i) = outputi;
   
   a = dec2bin(sigt2q, 10);
   b(1) = a(10);
   b(2) = a(9);
   b(3) = a(8);
   b(4) = a(7);
   b(5) = a(6);
   b(6) = a(5);
   b(7) = a(4);
   b(8) = a(3);
   b(9) = a(2);
   b(10) = a(1);
   outputq = bin2dec(b);
   
   test6(i) = outputq;
   
   % pack samples
   % wait until two complex samples are collected before writing into file
   if(mod(j,2) == 0)
      % even sample
      current_i = outputi;
      current_q = outputq;
      
      a = bitand(bitshift(last_q,-2), 255);
	   fprintf(fid_o1,'%c',a);
      a = bitand(bitor(bitshift(last_q,6),bitshift(last_i,-4)),255);
      fprintf(fid_o1,'%c',a);
      a = bitand(bitor(bitshift(last_i,4),bitshift(current_q,-6)),255);
      fprintf(fid_o1,'%c',a);
      a = bitand(bitor(bitshift(current_q,2),bitshift(current_i,-8)),255);
      fprintf(fid_o1,'%c',a);
      a = bitand(current_i,255);
      fprintf(fid_o1,'%c',a);
      
      % keep track of simulation progress
      if(mod(j,10000) == 0)
         j/10000
     	end;
      
   else
      % odd sample
	   % remember last sample
      last_i = outputi;
      last_q = outputq;
   end;
  

   
end   

   % plot of the sin (i and q values)
   plot(test1);
   title('I (blue) and Q (red) values for a Baseband signal composed of a Sinewave at 1MHz');
   hold on;
   plot(test2,'r');
   xlabel('samples');
   ylabel('amplitude');
   
% close opened files
fclose(fid_o1);