Altera_Forum
Honored Contributor
Honored ContributorCosine and Sine lookup table in vhdl
Hi i'm new to vhdl and I need a cosine and sine lookup table file in vhdl file already DONE.. because I don't have much time.. please help! thanks.
Forum Discussion
48 Replies
Altera_Forumvery useful, i've used it in my design:
http://opencores.org/project,verilog_cordic_core- Altera_Forum
sorry for all the duplicate messages
- Altera_Forum--- Quote Start --- very useful, i've used it in my design: http://opencores.org/project,verilog_cordic_core --- Quote End --- The answer is to my cuestion easo?
- Altera_Forum
Have this: A license file is required to enable compilation of your design for the Stratix II family devices. Visit Altera Licensing.... :(
- Altera_Forum
Hi,
I am new to FPGA and want to generate the sine wave. I read your threads and can you please tell me that i have to interface this sincos_lut.vhd file to DAC directly or i have to write some intermediate module? - Altera_Forum
If you want to generate the terms in sequence look up the Goertzel generator, one multiple and an add per term (from the previous 2):
sin(a+b) = 2sin(a)cos(b) - sin(a-b) - Altera_Forum--- Quote Start --- Attached a direct LUT in vhdl The input theta_in is the address, you can increment it as you wish to skip samples e.g. increment by 1 to use full table or by 2 to use half table or by 4 to use quarter table and so on. --- Quote End --- :D Helo!!! could you tell me, how to use this table?? the input theta is in dreegres?? and, how I have to interpret the outputs. thanks
- Altera_Forum
The input is 12 bits counter (not degrees but represents phase) and usually you start from zero and increment by tuning word(tw) as below. The LUT size is 4096 locations. data is 12 bits wise signed.
To produce a given frequency, you first need to know your sampling rate (Fs) then your required output frequency (Fo) then compute a tuning word: the ratio of tw/lut size = Fo/Fs i.e. tw = lut size * Fo/Fs = 4096 *Fo/Fs -- rounded up The lowest frequency is when tw = 1 and the highest frequency is when tw = 2048 i.e. the phase jumps 0 => 2048 => 0 You need to increment phase by tw modulo 4096. Hope this helps
