EMG data acquisition with Arduino

Heys guys , i need some help. I'm trying to comunicate Matlab with Arduino in a a more efficient way. I need to make an acquisition in real time of EMG data with 2 channels from an Arduino and Plot it. The data sampling frequency is 2000 Hz , I made an script that works like this : the matlab sends an number of samples to the arduino(between 0 and 200), then the arduino returns the same number to matlab . Then if the number recieved in matlab is the same as the number of samples , he receives the number of samples data in each channel. But it takes 8 seconds to plot 200 samples that is just 100ms of the data.

code :

   = serial('COM5'); %assigns the object s to serial port
set(s, 'InputBufferSize', 512); %number of bytes in inout buffer
set(s, 'FlowControl', 'None');
set(s, 'BaudRate', 9600);
set(s, 'Parity', 'None');
set(s, 'DataBits', 8);
set(s, 'StopBit', 1);
set(s, 'Timeout',5000);
fopen(s);           %opens the serial port
s.ReadAsyncMode = 'continuous';
amostras = 200;
figure(1)
tic
fprintf(s,int2str(amostras));
dado = fscanf(s,'%i'); 
if(dado(1) == amostras)
for i = 1:amostras
% 
dados(1,i) = fscanf(s,'%f');
dados(2,i) = fscanf(s,'%f');
drawnow;
sb1 = subplot(2,1,1);
plot(dados(1,:))
sb2 = subplot(2,1,2);
plot(dados(2,:))
axis([sb1 sb2],[1 amostras -1.2e+04 2.5e+03]);
% pause(0.01 - toc);
end
end  
dados = dados';
toc

With this code , it takes 8 seconds to plot the 200 samples , how can i make it work faster ? I'm thinking maybe its necessary to use the buffer , but how ?

the code of the arduino is :

if true
  % int led = 13;
long emg[2][200]= {{-2915.1071,-2811.9843,-2769.226,-2741.5589,-2731.4981,-2766.7108,-2781.802,-2834.621,-2884.9248,-2967.9262,-3045.8971,-3171.6567,-3262.2036,-3320.053,-3304.9618,-3249.6276,-3118.8377,-2945.2894,-2681.1943,-2429.6751,-2147.9737,-1926.6368,-1730.4519,-1604.6923,-1483.9631,-1403.4769,-1328.0212,-1302.8693,-1277.7174,-1277.7174,-1312.93,-1436.1744,-1627.329,-1931.6672,-2308.9459,-2789.3476,-3299.9315,-3870.88,-4419.1918,-4962.4732,-5488.1482,-6061.6119,-6682.8643,-7321.7229,-7948.0057,-8461.1048,-8838.3835,-9029.5381,-9052.1748,-8868.5658,-8559.1972,-8134.1298,-7706.5473,-7281.4799,-6889.11,-6494.2249,-6119.4613,-5737.1522,-5369.9342,-4919.7149,-4487.1019,-4021.7915,-3619.3608,-3249.6276,-2970.4414,-2691.2551,-2429.6751,-2175.6408,-1964.3647,-1750.5734,-1554.3884,-1363.2339,-1207.292,-1081.5324,-996.0159,-882.8323,-779.7094,-641.3739,-513.0991,-402.4307,-314.399,-228.8824,-140.8507,-83.0013,-7.5456,72.9406,193.6698,284.2167,397.4003,445.1889,503.0383,533.2206,575.9789,613.7068,651.4346,669.041,706.7689,744.4967,794.8006,807.3765,852.65,877.8019,950.7424,998.5311,1046.3197,1043.8045,1043.8045,1033.7438,1036.259,1043.8045,1041.2893,1033.7438,1028.7134,1033.7438,1028.7134,1028.7134,1038.7742,1068.9565,1119.2603,1194.716,1250.0503,1307.8997,1350.6579,1398.4466,1408.5073,1426.1137,1393.4162,1398.4466,1400.9618,1438.6896,1438.6896,1436.1744,1395.9314,1348.1427,1285.2629,1209.8072,1089.078,996.0159,915.5298,887.8627,880.3171,887.8627,867.7411,857.6804,837.5588,809.8917,769.6486,721.86,689.1625,651.4346,628.7979,588.5548,570.9485,555.8574,568.4333,583.5245,621.2523,628.7979,633.8283,628.7979,658.9802,664.0106,689.1625,699.2233,747.0119,774.679,809.8917,784.7398,736.9512,661.4954,598.6156,543.2814,508.0687,467.8257,425.0674,372.2484,357.1572,309.3686,286.7319,261.5799,264.0951,251.5192,236.428,181.0938,62.8798,-65.395,-228.8824,-402.4307,-636.3435,-865.2259,-1094.1084,-1282.7477,-1426.1137,-1544.3277,-1622.2986,-1617.2682,-1589.6011,-1524.2061,-1483.9631,-1436.1744},{-973.3792,-1003.5615,-1036.259,-1121.7755,-1217.3528,-1348.1427,-1488.9935,-1670.0873,-1828.5443,-1976.9406,-2097.6698,-2168.0952,-2175.6408,-2140.4281,-2049.8812,-1939.2128,-1785.7861,-1644.9353,-1494.0238,-1360.7187,-1227.4135,-1136.8666,-1051.3501,-970.864,-928.1057,-877.8019,-860.1955,-832.5284,-855.1652,-885.3475,-940.6817,-985.9551,-1041.2893,-1081.5324,-1096.6236,-1071.4716,-1046.3197,-953.2576,-872.7715,-749.5271,-656.465,-513.0991,-392.3699,-201.2153,-30.1823,201.2153,402.4307,603.646,749.5271,850.1348,887.8627,875.2867,814.9221,747.0119,613.7068,485.432,316.9142,145.8811,-42.7583,-246.4888,-455.2497,-653.9498,-847.6196,-1018.6526,-1156.9882,-1307.8997,-1431.1441,-1569.4796,-1697.7544,-1856.2114,-2052.3964,-2215.8839,-2419.6144,-2648.4968,-2869.8337,-3103.7465,-3302.4467,-3473.4797,-3586.6633,-3659.6039,-3659.6039,-3641.9975,-3574.0874,-3483.5405,-3355.2657,-3234.5365,-3076.0794,-2900.016,-2774.2564,-2625.8601,-2464.8878,-2301.4004,-2115.2762,-1904.0001,-1670.0873,-1416.0529,-1149.4426,-880.3171,-606.1612,-339.5509,-93.0621,153.4267,384.8243,631.3131,809.8917,1028.7134,1154.473,1280.2326,1325.506,1358.2035,1335.5668,1315.4452,1250.0503,1207.292,1154.473,1131.8362,1101.6539,1101.6539,1104.1691,1126.8059,1169.5641,1252.5654,1300.3541,1370.7795,1411.0225,1428.6289,1413.5377,1345.6275,1257.5958,1126.8059,998.5311,872.7715,784.7398,724.3752,711.7992,689.1625,726.8904,754.5575,812.4069,842.5892,887.8627,892.893,900.4386,870.2563,832.5284,741.9815,686.6473,570.9485,498.0079,402.4307,337.0357,286.7319,281.7015,294.2774,334.5205,397.4003,492.9776,586.0397,701.7385,799.8309,910.4994,990.9855,1081.5324,1111.7147,1116.7451,1109.1995,1056.3805,990.9855,905.469,814.9221,734.436,691.6777,661.4954,646.4043,616.222,593.5852,540.7662,520.6447,480.4016,470.3408,533.2206,679.1017,855.1652,1151.9578,1466.3567,1810.938,2100.185,2329.0675,2447.2815,2500.1005,2444.7663,2334.0979,2198.2775,2075.0331,1964.3647,1863.757,1833.5747,1743.0278,1685.1784,1617.2682}};
void setup() { 
pinMode(led, OUTPUT); 
Serial.begin(9600);
}
String leStringSerial(){
String conteudo = "";
char caractere;

// Enquanto receber algo pela serial
while(Serial.available() > 0) {
  // Lê byte da serial
  caractere = Serial.read();
  // Ignora caractere de quebra de linha
  if (caractere != '\n'){
    // Concatena valores
    conteudo.concat(caractere);
  }
  // Aguarda buffer serial ler próximo caractere
  delay(10);
}
Serial.println(conteudo);

return conteudo;
}
void loop() {
// Se receber algo pela serial
if (Serial.available() > 0){
  // Lê toda string recebida
  String recebido = leStringSerial();
  int a = recebido.toInt();
  if (a > 0 && a <= 200){
    digitalWrite(led, HIGH);
    for(int i=0;i< a;i++)
   {
     Serial.println(emg[0][i]);
     Serial.println(emg[1][i]);
   }
  }
  }

   delay(100); 
  }
  end

Can anyone help ?

[Crystiano Martins]

Nobody can help ?

[Star Strider]

There aren’t many people experienced with Arduino on MATLAB Answers. Most who are are MathWorks folks.

You might consider contacting MathWorks Support directly.