serial connection via matlab

[r.a.mccracken]

Hi,

I'm communicating with my RP via serial as I don't have an ethernet connection on my MacBook. I have managed to establish a Matlab connection and can output voltage signals, however I can't get seem to acquire data. When using 'query', the response is always the last command sent. I have attached code below - any help is appreciated!

Code: Select all

 s=serial'/dev/cu.usbserial-DB00FW8L','BaudRate',115200,'DataBits',8,'Parity','none','StopBits',1,'FlowControl','none','Terminator','CR/LF');
fopen(s);
fprintf(s,'root');     % This and following 'root' are necessary to login to the RP
pause(1);
fprintf(s,'root');
pause(1);
fclose(s);
s.InputBufferSize=16384*32;

fopen(s);
fprintf(s,'generate 1 1 200000 sqr');   % This command works, output has been checked on oscilloscope.
pause(1);
query(s,'acquire 1024 8');
fclose(s);

[Nils Roos]

According to this description, a 'query' without format specifiers reads single characters (default input format %c) from the com object until the first end of line. Thus, you only see the console echo of your command.

"acquire" outputs its results as pairs of values with a newline after each pair. So maybe instead of using 'query', you'd be better of sending the command with 'fprintf' and receiving the results with a series of 'fscanf'.

[r.a.mccracken]

Thanks for the quick reply. Could you be more specific about the pairs of values that are put out using acquire, for example are the unsigned/signed integers, floating point numbers, strings?

[Nils Roos]

From acquire.c:

Code: Select all

printf("%7d %7d\n", (int)s[1][i], (int)s[2][i]);

The array s contains the raw ADC samples from both channels.