Implementation of Cordic Algorithm for FPGA. Based Computers Using Verilog. pani1, ju, a3. The CORDIC rotator seeks to reduce the angle to zero by rotating the vector. To compute . See the description of the CORDIC algorithm for details. */ module. Tags: verilog code for cordic algorithm verilog code for vector verilog code for .. specific device designations, other words log Abstract.. code in the example.

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In MyHDL, a single type does it all – the intbv class.

## Cordic-based Sine Computer

We discussed some time ago how to go about this via rounding. T is also something that is easy to calculate within an FPGA.

The reason is that the convertible subset is much less restrictive. We will first write a unit test for the design. It cordjc only adds, subtracts, and shifts.

The number of stages and the number of bits in each stage can both be defined based upon arguments to the core generator program. This mode seeks to reduce the angle. Rotating to zero The next step is to rotate the xv[0] and yv[0] values through the remaining phase angle, ph[0].

This is what we are going to try to build today.

### Computing sin & cos in hardware with synthesisable Verilog

By filling in the parameters of the bench function, we can construct an verulog test bench that runs a simulation, as follows:. Our first problem, therefore is going to be rotating our incoming vector so that any remaining rotation amount is 45 degrees or less. To represent the numbers, we use the intbv class, which is basically an integer-like type with bit-vector capabilities.

Here is my code to compute sine and cosine of the input angle using cordic algorithm:. One would therefore expect a similar feature in other HDLs.

As the design will perform its calculations in finite precision, there will be rounding errors. Anyway, the cast is an additional safety net.

## Computing sin & cos in hardware with synthesisable Verilog

Note that outside the generator function, we calculate some data such as the X0 constant, and the look-up table of elementary arctangents, represented by the angles tuple. This define determines the number of bits used to represent the angle.

The dual nature of this class comes in very handy. You need to rotate the original vector by some multiple of ninety degree angles until the remaining rotation angle is less than forty five degrees. The user can change the number of bits that represent the x,y, and theta values. As long as the code inside them obeys the constraints of the convertible subset, the design instance can always be converted to Verilog.

We may want to use the test bench for designs with different characteristics; therefore, the error margin is made a parameter.

### Cordic Algorithm using Verilog – Electrical Engineering Stack Exchange

With the underlying two’s complement representation, it works for positive and negative values of y. In addition to the Verilog code for the design coddic, it also generates a Verilog test bench stub that defines an interface between the Verilog design and a Cosimulation object.

It seems corsic that a type that unifies the integer and the bit vector views should be very useful for hardware design. Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

For example, consider how the look-up table of elementary arctangents is set up in the SineComputer design:. The keyword arguments make the link between signal names declared in the Verilog test bench stub and signals in the MyHDL code.

This can become very tricky, especially with negative altorithm and the signed representation. To see this, first calculate the angles of the vectors in Fig 1 above:. For these applications, the way to compensate for the gain is to send a alogrithm number as an input. The goal of this section is to rotate the input by some number of ninety-degree intervals until the remaining phase is between and Because the Berilog algorithm will also increase the magnitude of the input, this process adds one more bit on the leftâ€”to allow for a touch of width expansion.

If more iterations or higher precision calculations are desired then a new arctan table will need to be computed.

For now, remember that the global CE strategy requires that nothing changes unless a CE line is true. This mode seeks to reduce the Y values and is used to compute an angle given a point. Other HDLs seem to verilkg to solve the issues by creating more and more integer and bit-vector like types.

Note that we have been talking about the convertible subset, and not about the “synthesizable subset”. It is important to realize that the conversion occurs on a design instance. Sign up using Email and Password.