Semaphores

UDP (User Datagram Protocol) is a fast and lightweight method for sending and receiving network messages. These messages are often “un-targeted,” meaning they may be broadcast to multiple receivers without requiring an acknowledgment or validation of the sender. This lack of confirmation is acceptable in cases where communication speed is essential, or when the sender’s identity is not important. In this context, UDP is ideal for transmitting informational messages, such as status updates or sensor readings, where receiving every message is not critical.

UDP is a way to rapidly send & receive on the network un-targeted messages, that generally are just informative and don’t need a validation of the sender (due to communication speed necessity or simply because there’s no need to pinpoint the sender). It should be simply used to validate messages or states.

Each semaphore broadcasts its status at a frequency of 5 Hz. These broadcasts include the semaphore’s position on the map and its current state (red, yellow, or green).

Semaphore state

Semaphore state	0	1	2
Color	RED	YELLOW	GREEN

Semaphore cycle

The cycle of each semaphore is described in the table below

Start Cycle

RED

GREEN

YELLOW

RED

To run

The API listens for UDP messages on port 5007. To intercept and test these messages, run the script located at src/data/Semaphores/processSemaphores.py.

For testing purposes, you can simulate the data transmission using a script found in the “Computer” project. Running this simulation on your computer will allow you to validate that data is being transmitted and received correctly.