18.6.2 Example 2

The angle output of CORDIC is represented with 18-bit resolution, where each bit contributes to the total 360° range. The contribution of each bit at position $κ$ is given by:

Equation 18-11.

\frac{180 °}{2^{(17 - κ)}}

where $κ$ = 17 to 0.

Table 18-3. Contribution of Each Bit to Angle Representation
Bit Position	Angle
17	180°
16	90°
15	45°
14	22.5°
13	11.25°
12	5.625°
11	2.812°
10	1.406°
9	0.703°
8	0.351°
7	0.175°
6	0.087°
5	0.043°
4	0.021°
3	0.010°
2	0.005°
1	0.002°
0	0.001°

The CORDIC block implements the rotation mode of the CORDIC algorithm. The algorithm begins by rotating the vector (x,y) = (1,0), which represents 45°. The inputs are fed to input CORDIC registers after multiplying the coordinates by the CORDIC gain, 0.6072. Hence, the coordinate inputs are RDCCORDXIN = 0x4DB88000 = 0.6072 and RDCCORDYIN = 0. Suppose the resolver angle is 225°, then using Table 18-3, RDCCORDANGIN = 0b101000000000000000 = 225°. Once the algorithm finishes, the resulting output will be available in CORDIC output registers. RDCCORDXOUT = 0xA5818000, RDCCORDYOUT = 0xA57E8000.