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The Cubesat Space Protocol
Cubesat Space Protocol (CSP) is a small protocol stack written in C. CSP
is designed to ease communication between distributed embedded systems
in smaller networks, such as Cubesats. The design follows the TCP/IP
model and includes a transport protocol, a routing protocol and several
MAC-layer interfaces. The core of
includes a router, a connection oriented socket API and
The protocol is based on an very lightweight header containing both transport and network-layer information. Its implementation is designed for, but not limited to, embedded systems with very limited CPU and memory resources. The implementation is written in GNU C and is currently ported to run on FreeRTOS, Zephyr and Linux (POSIX).
The idea is to give sub-system developers of cubesats the same features of a TCP/IP stack, but without adding the huge overhead of the IP header. The small footprint and simple implementation allows a small 8-bit system to be fully connected on the network. This allows all subsystems to provide their services on the same network level, without any master node required. Using a service oriented architecture has several advantages compared to the traditional mater/slave topology used on many cubesats.
Standardised network protocol: All subsystems can communicate with eachother (multi-master)
Service loose coupling: Services maintain a relationship that minimizes dependencies between subsystems
Service abstraction: Beyond descriptions in the service contract, services hide logic from the outside world
Service reusability: Logic is divided into services with the intention of promoting reuse.
Service autonomy: Services have control over the logic they encapsulate.
Service Redundancy: Easily add redundant services to the bus
Reduces single point of failure: The complexity is moved from a single master node to several well defined services on the network
The implementation of
libcsp is written
with simplicity in mind, but it’s compile time configuration allows it
to have some rather advanced features as well.
Thread safe Socket API
Router task with Quality of Services
Connection-oriented operation (RFC 908 and 1151).
Connection-less operation (similar to UDP)
ICMP-like requests such as ping and buffer status.
Very Small Footprint in regards to code and memory required
Zero-copy buffer and queue system
Modular network interface system
OS abstraction, currently ported to: FreeRTOS, Zephyr, Linux
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