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???
05/17/12 03:24
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#187386 - digital sine wave
Responding to: ???'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            01/01/70 00:00      
   What frequency Sine wave & Clock ?            01/01/70 00:00      
      Thank you            01/01/70 00:00      
         DDS (Direct Digital Synthesis)            01/01/70 00:00      
         digital sine wave            01/01/70 00:00      
            uC sine generator            01/01/70 00:00      
               DMA            01/01/70 00:00      
               neither do I            01/01/70 00:00      
                  ARN            01/01/70 00:00      
                  'F120 Series            01/01/70 00:00      
               Other solutions            01/01/70 00:00      
               150nS access time is so long            01/01/70 00:00      
            is that realy the case?            01/01/70 00:00      
   Of course my solution            01/01/70 00:00      
      Hmmm.., nice but...            01/01/70 00:00      
         Those are actually PALs not CPLDs            01/01/70 00:00      
         ATF750CL for PT clocks            01/01/70 00:00      
            ATF750            01/01/70 00:00      
               ATF750C ?            01/01/70 00:00      
                  Yes, Jim You are exactly right.            01/01/70 00:00      
                     Can I suggest            01/01/70 00:00      
                     ATDH1150USB            01/01/70 00:00      
                        Update : ATDH1150VPC            01/01/70 00:00      
                        Thanks JIM            01/01/70 00:00      

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