The Sine Wave Pattern Generator serves as a data generator that provides data for the AXI streaming interface. The sine wave generator, as the name implies, generates values in the form of sine waves. The values are generated from the angular phase, which is controlled by the inc (increment) register. Other parameters that influence the sine wave are gain, multiplier with a range of 0 - 1.999..., and offset with a range of -2 to 1.999....
CORDIC (COordinate Rotation DIgital Computer) is a hardware-efficient iterative method that uses rotations to compute a wide range of elementary functions. The RTL uses the CORDIC algorithm as a primitive method for generating sinusoidal values from phase. The behavior of the CORDIC algorithm is controlled by the following input registers:
The output is represented by the following registers:
Some other inputs are:
The output is a 2f16 signed value with a frequency of 100MHz.
Cocotb is used for the testbench environment. It allows the user to access all RTL signals, control them and influence their behavior. In this case, the testbench accesses and modifies the phase increment value (inc_val_q_i), the gain factor (gain_val_q_i) and the offset (offset_val_q_i), as well as the system clock, reset and data generation enable. On the other hand, the testbench receives sine values from RTL via the sine_out output line. Just as RTL performs the calculation of the sine value using the CORDIC algorithm, the Testbench can import the sin() function from the math library. With the corresponding calculation, the sine value is output in hexadecimal form. The verification of the values calculated in the testbench and the values from the CORDIC algorithm is explained in detail in the following section.