How to create sine and cos waves of different frequencies using Cyclone III(VHDL)

[Altera_Forum]

Hi, 

 Is there anyone can help me to deal with one problem: How to create sine or cos waves in Cyclone III FPGA in VHDL. I have no clear idea to program the VHDL code although I have search some documents.  I will be much appreciate if someone can help me out.  Thank you very much.  Best wishes,  peipei

[Altera_Forum]

If you have no VHDL knowledge, my first suggestion would be to find a good tutorial and get yourself familiar with the language. 

 As for the sin waves, sine and cosine are identical, but with a phase shift. It would be easy enough to build a ROM of sin values in VHDL and just read them out.

[Altera_Forum]

Or read up on Goertzel.

[Altera_Forum]

There are many methods that can be used, A simple lookup table is the easiest, then just step through the lookup table at different rates. 

 If you truly want to generate Sin and Cos values, a CORDIC algorithm is the way to go.  Pete

[Altera_Forum]

If it was me I will use the altera ip away from manual hdl coding. I think cordic is too much for a beginner to hand code or understand.

[Altera_Forum]

--- Quote Start ---  If it was me I will use the altera ip away from manual hdl coding. I think cordic is too much for a beginner to hand code or understand.  --- Quote End ---   Does altera provide cordic IP for user now?

[Altera_Forum]

Hi Tricky, 

 I have learnt VHDL and I suppose I have some knowledge of this language.  But just for this application, I have not clear idea to achieve this.  In my mind, I want to use Look up table, due to the ADA board is 14 bits, and I have generated the different values in Excel for one cycle, I am not sure should I generate all 2^14 values or not.  Thanks for your reply.  Best wishes,  peipei  --- Quote Start ---  If you have no VHDL knowledge, my first suggestion would be to find a good tutorial and get yourself familiar with the language.  As for the sin waves, sine and cosine are identical, but with a phase shift. It would be easy enough to build a ROM of sin values in VHDL and just read them out.  --- Quote End ---  

[Altera_Forum]

Hi Jerry, 

 I am planning to use LUT.  Do you have specific suggestions? My ADA board is 14 bits.  Thanks,  Best wishes,  peipei  --- Quote Start ---  Does altera provide cordic IP for user now?  --- Quote End ---  

[Altera_Forum]

Remember Sin and cosine are reflective, so you only need 2^13 values in the rom, you use the 14th bit as the sign bit.

[Altera_Forum]

CORDIC is suitable for generating the sin/cos of an angle. 

You can generate sin(a + delta) from sin(a - delta) and sin(a) with a single multiply (and a shift). The only slight problen is that the amplitude can drift.