acquire_trigger_software Example program not working

[tknopp]

Hi,

I have trouble with data recording on the fast DAQ. I followed these instructions:
http://wiki.redpitaya.com/index.php?tit ... le_program

and compiled the program: acquire_trigger_software. I then executed:
LD_LIBRARY_PATH=/opt/redpitaya/lib ./acquire_trigger_software > test.txt
and copied the result to the host computer. When I plot the data it does not show a continuous sinus but many discontinuities. Is that expected for this example program?

It would further be interesting if these examples use SCPI or not. I would say no, because it runs on the RP but there is a comment on SCPI in that example file.

Thanks

Tobias

[Nils Roos]

Hi Tobias,

what did you connect to input 1? The example code generates a 20kHz sine wave on output 1 and records input 1 at 15.625MSps .

It would further be interesting if these examples use SCPI or not.

They do not.

[tknopp]

Thanks, I did something completely stupid and had the oscilloscope app running while performing the measurement. Now it works. For some reason the signal is clipping when I am using 1V output signal. Not sure why.

[Nils Roos]

Do you terminate the output with 50ohm? Without proper termination, the output will deviate noticably from the expected voltage range.

[tknopp]

I have an SMA cable from CH1 input to CH1 output. Do I need to put 50 Ohms in series?

[Nils Roos]

You need a 50ohm termination on the output and connect the scope input across that termination (=> in parallel). This is commonly done with a T-connector with the termination resistor connected to one leg and the scope to the other.

[tknopp]

Ah yes, thanks! Forgot about that.

Cheers,

Tobias