PJON

PJON 13.1

PJON (Padded Jittering Operative Network) is an experimental, multi-master, software-defined network protocol that can be easily cross-compiled for many microcontrollers and real-time operating systems such as ATtiny, ATmega, SAMD, ESP8266, ESP32, STM32, Teensy, Raspberry Pi, Zephyr, Linux, Windows x86, Apple, and Android. PJON operates over a wide range of media, data links, and existing protocols like PJDL, PJDLR, PJDLS, Serial, RS485, USB, ASK/FSK, LoRa, UDP, TCP, MQTT, and ESPNOW. For more information, visit the documentation, the specification, or the wiki.

Why PJON?

• New technology: PJON is an experimental network protocol stack crafted through 10 years of research and experimentation. It was originally developed as an open-source alternative to i2c and 1-Wire, but during development, its scope and features were extended to cover use cases where IP is generally applied. PJON has been engineered to have a variable footprint (4.2–8.2 kB program memory) and overhead (5–35 bytes per packet) depending on its configuration.
• Multi-media support: PJON operates over a wide range of protocols including TCP, UDP, MQTT, ESPNOW, USB, Serial, RS485, and LoRa. The PJON network protocol stack also specifies and implements PJDL that operates over a single wire of up to 2000m shared by up to 255 devices, PJDLR that operates with many ASK/FSK/OOK radio modules and PJDLS that operates wirelessly with light pulses using off-the-shelf LEDs and laser diodes.
• Increased reliability: Many widely applied protocols expose significant vulnerabilities, have weak error detection algorithms, and are not resilient to interference. PJON is based on years of analysis and study to avoid the mistakes present in most alternatives and provide with a simpler and more efficient solution.
• High flexibility: PJON is fully software-defined and designed to be easily extensible. It builds out-of-the-box on all supported devices and operates transparently on top of any supported protocol or medium.
• Low cost: With no additional hardware needed to operate, minimal network wiring requirements, and direct pin-to-pin or LED-to-LED communication, PJON is extremely energy-efficient, inexpensive to implement, and maintain. This experimental reference implementation is kept up to date thanks to the strong commitment of its growing community.

Features

• Cross-compilation support with the interfaces system calls abstraction.
• Multi-media support with the strategies data link layer abstraction.
• Modular packet format that includes only the fields used (overhead 5–35 bytes).
• Hot-swap support, no need for a system reset or shutdown when replacing or adding devices.
• Flexible local (device ID) and shared (bus ID) network identification.
• Safe error detection using modern CRC8 and CRC32 polynomials.
• Optional inclusion of MAC addresses.
• Optional acknowledgement.
• Error handling.

Academic studies

Researchers are active in many universities worldwide using PJON in different environments. The following list contains known published academic studies about PJON:

• Definition and Application of PJON-PLC for sensor networks by Jorge Gómez Segurola, Ingeniería de Tecnologías de Telecomunicación - Universidad de Cantabria (ES).
• Biomimetic electronics by Charlie Williams with scientific input from researchers Vítor Martins dos Santos, Diana Machado de Sousa, and Sabine Vreeburg - Artist in Residency at Wageningen University (NL).
• LANC Video Camera Control by Jack Anderson - Department of Computer Science Loughborough University (UK).
• Implementation of a PJON hardware peripheral for the Croc SoC by Pius Sieber - ETH Zurich (CH)

Contribute

Feel free to send a pull request sharing something you have made that could help, if you want to support this project you can also try to solve an issue. Thanks to support, expertise, kindness and talent of the following contributors, the protocol's documentation, specification and implementation have been strongly tested, enhanced and verified:

Fred Larsen, Zbigniew Zasieczny, Matheus Garbelini, sticilface, Felix Barbalet, Oleh Halitskiy, fotosettore, fabpolli, Adrian Sławiński, Osman Selçuk Aktepe, Jorgen-VikingGod, drtrigon, Endre Karlson, Wilfried Klaas, budaics, ibantxo, gonnavis, maxidroms83, Evgeny Dontsov, zcattacz, Valerii Koval, Ivan Kravets, Esben Soeltoft, Alex Grishin, Andrew Grande, Michael Teeww, Paolo Paolucci, per1234, Santiago Castro, pacproduct, elusive-code, Emanuele Iannone, Christian Pointner, Fabian Gärtner, Mauro Mombelli, Remo Kallio, hyndruide, sigmaeo, filogranaf, Maximiliano Duarte, Viktor Szépe, Shachar Limor, Pantovich, Mauro Zancarlin, Franketto, jzobac, DanRoad, fcastrovilli, Andrei Volkau, maniekq, DetAtHome, Michael Branson, chestwood96, Mattze96, Steven Bense, Jack Anderson, callalilychen, Julio Aguirre, Cimex97, der-schne, porkyneal, der-schne, Rainer Schoenberger, jgOhYeah and kuchendieb.

Compliant tools

• ModuleInterface - easy config and value sync between IoT modules by Fred Larsen
• PJON-cython - cython PJON wrapper by xlfe github user
• PJON-piper - command line wrapper by Zbigniew Zasieczny
• PJON-python - python interface by Zbigniew Zasieczny
• PJON-gRPC - gRPC server-client by Oleh Halytskyi
• PjonHL - PjonHL is a highlevel wrapper around PJON

License

All the software included in this project is experimental and it is distributed "AS IS" without any warranty, use it at your own risk. Licensed under the Apache License, Version 2.0.

Safety warning

When testing PJON, take extreme care to avoid any danger. The implementation is experimental and may not behave as expected; use it at your own risk. If devices are connected to AC power, you face a high risk of electrocution unless the hardware is installed carefully and correctly. If you lack sufficient experience, seek assistance from a qualified technician, and be aware that many countries prohibit uncertified installations. When testing a SoftwareBitBang bus follow interference-mitigation and protective-circuitry guidelines. When experimenting with an AnalogSampling setup, wear safety glasses and operate transceivers cautiously to prevent eye injuries. Before testing OverSampling, ThroughSerial or ThroughLoRa radio communication, ensure that the frequency, power, and hardware comply with local regulations. When connecting a local bus to the Internet, treat all devices as potentially compromised, manipulated, or remotely actuated against your will. As a best practice, avoid connecting to the internet systems that could cause damage (fire, flood, data leakage) if hacked.