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Andy Peters
05/16/12 21:24
Read: 760 times
Tucson, Az
USA


 
#187386 - digital sine wave
Responding to: Jason Arkwright's previous message
Jason Arkwright said:
Hi Jim,

I need to generate a sinewave with quadrature outputs, speed wise >1kHz. Do you have an alternative to generating a digitally derived sinewave?


There are two aspects to this problem:
a) generating the sine values.
b) creating an analog output.

The generation problem is pretty easy. You can do a lookup table in an FPGA; that lookup table is what's implemented in that ROM you can't find, and the smallest FPGAs have more resources anyway. You need a counter at some nominal sample frequency to read the lookup table.

Or you could use a microcontroller to generate sine values, again using a lookup table or perhaps just calling a math library with a sine function. Use a timer to get a new value on a regular interval.

The second half of the problem is generating the output. Most micros have built-in DACs, so you simply scale the sine function output (a real number between -1 and 1) to the DAC's output range. Or just configure the lookup table to give you exact DAC outputs.

Or connect an SPI or I2C or I2S DAC to your micro or FPGA output.

You could even do PWM to generate the sine wave analog output.

Lots of options!

-a

List of 24 messages in thread
TopicAuthorDate
256bit x 8 proms      Jason Arkwright      05/15/12 04:44      
   What frequency Sine wave & Clock ?      Jim Granville      05/15/12 05:37      
      Thank you      Jason Arkwright      05/15/12 08:10      
         DDS (Direct Digital Synthesis)      Jim Granville      05/15/12 17:49      
         digital sine wave      Andy Peters      05/16/12 21:24      
            uC sine generator      Jason Arkwright      05/17/12 04:36      
               DMA      Aubrey Kagan      05/17/12 06:43      
               neither do I      Erik Malund      05/17/12 07:07      
                  ARN      Michael Karas      05/17/12 15:30      
                  'F120 Series      Michael Karas      05/17/12 15:58      
               Other solutions      Jim Granville      05/17/12 20:12      
               150nS access time is so long      Justin Fontes      05/17/12 22:13      
            is that realy the case?      Richard Erlacher      05/23/12 16:21      
   Of course my solution      Jez Smith      05/19/12 09:11      
      Hmmm.., nice but...      Jason Arkwright      05/20/12 12:29      
         Those are actually PALs not CPLDs      Jez Smith      05/20/12 12:44      
         ATF750CL for PT clocks      Jim Granville      05/20/12 16:38      
            ATF750      Jason Arkwright      05/21/12 09:21      
               ATF750C ?      Jim Granville      05/22/12 23:42      
                  Yes, Jim You are exactly right.      Jason Arkwright      05/26/12 12:49      
                     Can I suggest      Jez Smith      05/26/12 14:00      
                     ATDH1150USB      Jim Granville      05/26/12 19:45      
                        Update : ATDH1150VPC      Jim Granville      05/27/12 05:57      
                        Thanks JIM      Jason Arkwright      05/31/12 15:57      

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