173 UART Matrix Multiplier :: Quicker, easier and cheaper to make your own chip!

How it works

This project implements a 2x2 matrix multiplier that communicates via UART. The design receives two 2x2 matrices through UART serial communication, performs matrix multiplication, and transmits the result back via UART.

Matrix Multiplication Process:

Input: Two 2x2 matrices A and B
Matrix A = [[A0, A1], [A2, A3]]
Matrix B = [[B0, B1], [B2, B3]]
Result C = A × B = [[C00, C01], [C10, C11]]

Where:

C00 = A0×B0 + A1×B2
C01 = A0×B1 + A1×B3
C10 = A2×B0 + A3×B2
C11 = A2×B1 + A3×B3

Communication Protocol:

UART configuration: 115,200 baud, 8N1 (8 data bits, no parity, 1 stop bit)
Input: 8 bytes sent sequentially (A0, A1, A2, A3, B0, B1, B2, B3)
Output: 4 bytes sent sequentially (C00, C01, C10, C11) - lower 8 bits of each result
Parallel output: Result matrix elements are also available on dedicated output pins

State Machine:

Wait for UART input (8 bytes)
Compute matrix multiplication
Transmit results via UART (4 bytes)
Return to waiting state

How to test

Required Setup:

UART terminal or microcontroller capable of serial communication
Connection to ui[0] (UART RX) and uio[0] (UART TX)
100MHz clock input
Active-low reset

Testing Procedure:

Connect UART interface:
- Connect UART TX from your device to ui[0] (chip's RX input)
- Connect UART RX from your device to uio[0] (chip's TX output)
- Set terminal to 120,000 baud, 8N1

Send test matrices: Send 8 bytes in sequence representing matrices A and B:

Example: A = [[1,2],[3,4]], B = [[5,6],[7,8]]
Send bytes: 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08

Receive results: The chip will respond with 4 bytes representing the result matrix C:
```
Expected result: C = [[19,22],[43,50]]
Received bytes: 0x13, 0x16, 0x2B, 0x32
```
Monitor parallel outputs:
- uo[0]: C00 (lower 8 bits)
- uo[1]: C01 (lower 8 bits)
- uo[2]: C10 (lower 8 bits)
- uo[3]: C11 (lower 8 bits)

Test Cases:

Identity matrix: A = [[1,0],[0,1]], B = [[5,6],[7,8]] → C = [[5,6],[7,8]]
Zero matrix: A = [[0,0],[0,0]], B = any matrix → C = [[0,0],[0,0]]
Small values: Test with single-digit numbers to verify correctness
Edge cases: Test with values that might cause overflow (results > 255)

External hardware

Required:

USB cable (USB-A to Micro-USB or USB-C, depending on your development board. Testing was performed using a Micro-USB cable.)
No additional UART adapter needed - uses built-in USB-UART bridge

Optional:

Logic analyzer or oscilloscope for debugging UART communication
LED indicators connected to parallel output pins (uo[0:3]) to visualize results
Push button for manual reset control

Connection Setup:

USB Connection: Connect USB cable directly to development board
UART Interface: Automatically available through built-in FTDI USB-UART bridge
- ui[0]: Connected to FTDI TX (receives data from computer)
- uio[0]: Connected to FTDI RX (sends data to computer)
Parallel Outputs: uo[0:3] available for monitoring or LED indicators
Clock/Reset: Handled by board's built-in clock and reset circuitry

Computer Setup:

Install FTDI drivers if not automatically detected
The board will appear as a COM port (Windows) or /dev/ttyUSB* (Linux/Mac)
You may use the mmult_comm.py file at the base of this repository to test the chip.

UART Settings:

Baud rate: 120,000
Data bits: 8
Parity: None
Stop bits: 1
Flow control: None

Usage:

Connect USB cable to development board
Open serial terminal and connect to the board's COM port
Send 8 bytes representing your two 2x2 matrices
Receive 4 bytes back representing the result matrix
Optionally monitor parallel outputs on uo[0:3] pins

Credits

Special thanks to Mr. Tim Edwards for his assistance and mentorship throughout this project
Mr. Zach Kingman for providing the opportunity to complete this project during school hours.
Tiny Tapeout team

#	Input	Output	Bidirectional
0	UART RX	Matrix Result C00[7:0]	UART TX
1		Matrix Result C01[7:0]
2		Matrix Result C10[7:0]
3		Matrix Result C11[7:0]
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173 UART Matrix Multiplier