Get only numbers from serial port without any str2num() conversion
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Sergey Makovkin
el 25 de Mzo. de 2016
Comentada: Walter Roberson
el 28 de Mzo. de 2016
Hi all!
In the serial com port channel values comes from 0 to 1023, this example from Arduino: https://monosnap.com/file/TiTehc6zWhu0zszPnCALbnjIMAfpzf
On the MATLAB side I parse it via function:
function sPs = GetsP()
global obj1;
sPs = 0;
while(obj1.BytesAvailable)
Psvoltage = fscanf(obj1);
if (~isempty(Psvoltage))
sPs = str2num(Psvoltage) * (100 / 1023);
break;
end
end
But I dont like this variant, because str2num() conversion is very slow. If I try to use Psvoltage = fread(obj1, 1, 'ushort'); I didnt see correct data, because fread() reads binary data.
So the question is: How can I try to read direct number data, without any slow string to number conversion? How can I need to use fread() to get numbers?
3 comentarios
Walter Roberson
el 28 de Mzo. de 2016
Reprogram the arduino code to send uint16 instead of text. You only need 10 bits of the 16, so you could even pack in some flags like "Beginning of Row" to help synchronize. Or you could take advantage of the extra 6 bits to add error correcting codes to make it easier to recover from potential dropped bytes.
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Walter Roberson
el 25 de Mzo. de 2016
str2num() uses a full eval() . str2double() is faster. You can also use fscanf with a format specifier,
fscanf(obj1, '%d')
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