Request - Low frequency arbitrary function generator

Have an idea? Post it here! - Looking for developers? Ask here as well!
Post Reply
GreginBSE
Posts: 3
Joined: Sat Nov 29, 2014 10:43 am

Request - Low frequency arbitrary function generator

Post by GreginBSE » Sat Nov 29, 2014 10:49 am

I have an application which requires a low frequency arbitrary function generator. Ideally I'd like to be able to set an amplitude (read from a .CSV file) every second or so. It looks like a 100Hz setting on the signal generator app is the lowest possible. The maximum number of points of 16383 is fine.
If anyone can suggest a way to achieve what I'm looking for with the existing software, that would be great. Otherwise, it's one for the wish list.

Nils Roos
Posts: 1441
Joined: Sat Jun 07, 2014 12:49 pm
Location: Königswinter

Re: Request - Low frequency arbitrary function generator

Post by Nils Roos » Sun Nov 30, 2014 6:29 pm

Are you looking to output 1 sample every second ? Or do you want to change the amplitude of a higher (but still low) frequency signal every second ?

GreginBSE
Posts: 3
Joined: Sat Nov 29, 2014 10:43 am

Re: Request - Low frequency arbitrary function generator

Post by GreginBSE » Mon Dec 01, 2014 7:47 pm

I'm just looking for the value in the .CSV file to be read every second, and for that to be the output level until the next value is read from the .CSV. The output will be converted to a 4-20mA signal for a process control application.

Nils Roos
Posts: 1441
Joined: Sat Jun 07, 2014 12:49 pm
Location: Königswinter

Re: Request - Low frequency arbitrary function generator

Post by Nils Roos » Mon Dec 01, 2014 8:26 pm

There is a really simple solution to your requirement:

The default generator settings are such that the first value in the output buffer will continuously be output through the DAC. Just issue

Code: Select all

monitor 0x40210000 <value 0x2000 - 0x1fff> //(for channel A)
monitor 0x40220000 <value 0x2000 - 0x1fff> //(for channel B)
on the command line and the value will appear as DC on the DAC outlets.

The range of values is 14bit two-s complement, 0x2000 = -16384 = -1.0V, 0x1fff = 16383 = 1.0V (roughly).

Writing a script that reads CSV and calls monitor every second should be easy.

I noticed that the scope application seems to interfere with the generator settings, so it is best to avoid using the web-apps while running your RedPitaya in that way.

GreginBSE
Posts: 3
Joined: Sat Nov 29, 2014 10:43 am

Re: Request - Low frequency arbitrary function generator

Post by GreginBSE » Tue Dec 02, 2014 8:24 pm

Thank you Nils.

I'm a complete beginner. I'll take a look and see how I get on.

Post Reply
jadalnie klasyczne ekskluzywne meble wypoczynkowe do salonu ekskluzywne meble tapicerowane ekskluzywne meble do sypialni ekskluzywne meble włoskie

Who is online

Users browsing this forum: No registered users and 2 guests