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11 Threads found on edaboard.com: Lookup Table Dds
I'm not aware of a simple single chip dds solution that includes arbitrary waveforms (RAM lookup table). For the intended low frequency range, a dds generator with RAM lookup table can be well implemented in a single chip processor. ARM or dsPIC with built-in DAC could be used, otherwise an (...)
hi frnds i wan to make v/f control of 3phase acim successfuly i generate 3 phase sine wave, which frequency can vary frm 1hz to 1023hz using 3 phase dds by sine lookup table, timer,interrupt. now i wana to implement V/F i attached my program /****************************************************************** * (...)
The dds is pretty simple. If you want simpler, just use a lookup table.
It sounds as though you're using a method that will have lookup tables consisting of partial sine waves. First and last values may be far apart. This will result in sudden transitions at the speaker. You'll get harsh sounding sine waves. You only need one lookup table. You stated your memory has room for 44 x 256 (...)
You will need a block of RAM that takes the values of your calculations. The LUT that was referred to is a lookup table, not the LUT that is a hardware part of a logic element within an FPGA.
First of all, you do not need to change the lookup table (the table where you store the sine wave values) as the output frequency changes. The waveform will be always the same, the only change will be the speed that the points of the table are converted to analog signal. The solution for your problem is the (...)
the diagram below shows my design to generate a sine wave ... but its not generating it .... help needed there any need to create a lookup table inside the dds block .. or its there by defalult ...? If it is required to create a lookup table manually then h
Are you using a Xilinx device? Which one? Try the "dds Compiler" or "Direct Digital Synthesizer" cores included with Xilinx ISE CORE Generator. Or build your own dds. Feed a frequency constant into an ordinary arithmetic accumulator. Connect the accumulator output to the address inputs of a sinewave lookup table ROM. (...)
Hi, i think the best way to do this is to make a lookup table with stored digital values of a single cycle of a sine wave and raster on this value with ur required frequency, also offcourse u need DAC to get ur analog signal. good luck.
Maybe this will you repeatedly add a constant to an integer accumulator, and then use the most significant bits of the accumulator as an index into a sinewave lookup table. Please, can you upload the ddssim.zip file of that page as well as its useful
Can you please explain what all that code is trying to do? A dds normally has one accumulator plus a few lines of code for table lookup and phase modulation. Sort of like this: module top (clk, reset, fc, pc, sinout, cosout); input clk, reset; input fc, pc; reg acc0, phase; reg