TEJ4M Computer Interfacing Lab

Source and CAD for the TEJ4M computer interfacing lab.

The goal of this project is to develop a dual-processor system, linked over USB/UART, where the host has cryptographic random number generation capabilities and the coprocessor has a small 7-segment display. The idea is that any time a specific button is pressed, a new truly random number will be displayed.

Source layout

The source code is split into three modules:

• common
  • Common code between the host and coprocessor
• desktop
  • The host code
• coprocessor
  • The coprocessor code

Building

Configure the toolchain:

rustup toolchain install nightly-2020-11-20
rustup component add rust-src rls-preview rust-analysis --toolchain nightly-2020-11-20
sudo apt-get install binutils gcc-avr avr-libc avrdude

Build the desktop side of the project:

./scripts/build-desktop.sh

Build the avr side of the project:

./scripts/build-coprocessor.sh

Schematic & Photo

The multi-processor communication protocol

Communication between the two devices is done via a simple "question-answer" system, described below, and implemented in common/src/protocol/mod.rs.

Request

Data	Size	Description
0x01	u8	Packet type (request)
size	u8	Packet size after this byte
request	u8	Type of data requested

Response

Data	Size	Description
0x02	u8	Packet type (response)
size	u8	Packet size after this byte
payload	u8	Response payload