451 Tbilisi CORDIC Engine
451 : Tbilisi CORDIC Engine
- Author: Levan Chagelishvili
- Description: A fixed-point CORDIC engine that calculates sine and cosine using iterative shift-and-add operations.
- GitHub repository
- Open in 3D viewer
- Open in Tiny Tapeout Explorer
- Open in VGA Playground
- Clock: 50000000 Hz
How it works
The Tbilisi CORDIC Engine calculates sine and cosine using the iterative CORDIC rotation algorithm. It uses only arithmetic shifts, additions, and subtractions, avoiding hardware multipliers.
When start is asserted while calc is low, the engine accepts the selected angle and initializes the working vector with x = 1/K and y = 0, where K is the CORDIC gain. It then performs 14 micro-rotation iterations. During every iteration, the direction of rotation is selected from the sign of the remaining angle.
calc remains high while the calculation is running. After the final iteration, calc returns low and finish is asserted for one clock cycle. The calculated sine and cosine values are output on sin_out and cos_out.
The angle is represented by a 16-bit fixed-point value in which 16'h0000 represents 0 degrees and 16'h4000 represents 90 degrees. The top-level design contains 16 predefined angles from 0 to 90 degrees in steps of 6 degrees. Each accepted start request selects the current angle and advances the angle index for the next calculation.
The sine and cosine outputs are signed 16-bit fixed-point values with 15 fractional bits.
How to test
TODO: Explain how to use your project
External hardware
TODO: List external hardware used in your project (e.g. PMOD, LED display, etc), if any
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | switch [0] | VGA red [1] | |
| 1 | switch [1] | VGA green [1] | |
| 2 | switch [2] | VGA blue [1] | |
| 3 | switch [3] | VGA vsync | |
| 4 | switch [4] | VGA red [0] | output sticky_failure |
| 5 | switch [5] | VGA green [0] | TM1638 inout dio |
| 6 | switch [6] | VGA blue [0] | TM1638 output clk |
| 7 | UART rx | VGA hsync | TM1638 output stb |