Embedded Systems/Common Protocols

This is a list of common protocols used in embedded systems. Eventually, this list will become hyperlinks to sources of information on each. Many of them are byte-stream protocols that can be transmitted by a variety of serial protocols on a variety of hardware.

• I²C
• RS-485 is an extremely common hardware arrangement used by many embedded protocols:
  • CAN on top of RS485
  • DeviceNet on top of CAN. Wikipedia: DeviceNet
  • NMEA 2000 on top of DeviceNet. Wikipedia: NMEA 2000
  • DMX on top of RS485. Wikipedia: DMX512
  • Modbus on top of RS485
  • see Serial Programming/RS-485, Robotics/Computer Control/The Interface/Networks#RS485, Embedded Control Systems Design/Field busses, Embedded Systems/Serial and Parallel IO#RS-485
• MIDI. official MIDI interface schematics (1); beautiful MIDI IN schematic (2).
• BlueTooth
• InfraRed
• ZigBee
• SPI
• RS-232
• USB
• IP Over Serial Connections
• MINES (Microcontroller Interpreter for Networked Embedded Systems) was designed for very small embedded systems (see Gallery of MINES Devices).
• the Tiny Embedded Network
• IEEE Standard for Sensor Transducer Interface
• the three byte Mini SSC protocol (and another Mini SSC protocol example)
• JTAG
• NTSC / PAL television video output: w:TV Typewriter, Generating TV signal by PSoC, Generating TV signal with the PICs, PIC Breakout, ... Parallax Propeller has a video generator ...
• The low-latency Myrinet protocol is used in over 100 of the TOP500 supercomputers, as of June 2005.
• The low-latency InfiniBand protocol is used in over 100 of the TOP500 supercomputers, as of November 2010.
• The various Audio over Ethernet (AoE) protocols are generally designed to be relatively low latency.
• The LIN-Bus (w:Local Interconnect Network), a low-cost vehicle communication network
• Modbus (w:Modbus) protocol works over a variety of hardware interfaces, including
  • Modbus RTU over RS-485
  • Modbus ASCII over 7-bit asynchronous serial lines
  • Modbus TCP over Ethernet
• Firmata is a generic protocol that allows people to completely control the Arduino from software on a host computer. Arduino reference for Firmata; Firmata wiki.
• rosserial "rosserial ... is a general protocol for sending ROS messages over serial links." Code is available for Arduino and a variety of other platforms. (It was designed for ROS, the w: Robot Operating System).
• S.N.A.P - Scaleable Node Address Protocol [1] is media-independent, building on an underlying byte-oriented communication layer.
• Yet Another Scalable Protocol (YASP)
• Labor-Octet-Protocol (LOP) is a simple protocol originally implemented on AVR microcontrollers; it builds on an underlying byte-oriented communication layer and provides support for both message-oriented (all-or-nothing) and stream-oriented communication.
• Inter-Chip Serial Communications (ICSC) is a simple, high-reliability media-independent protocol originally implemented on Arduino.
• Perhaps the simplest-to-parse variable-size packet container format is the netstring format.w:netstring
• JSON (perhaps encapsulated in packets of one of the above formats) seems to be gaining popularity as a way to transmit complex data structures, in a way that is easy for humans to read and debug.[2] w:JSON

Further reading

If you are designing a new protocol because none of these meet your needs (which are what, exactly?), you may want to consider the w:Network protocol design principles, some Serial Programming/Forming Data Packets tips, ponder Communication Systems and Data Coding Theory, select one of the Serial Programming/Error Correction Methods, and post rough drafts to the PICA standards wiki for expert review.

Typically an embedded system has one "main" CPU and a bunch of peripheral devices. Is there a way for the main CPU to automatically find out how many peripheral devices are currently connected, and the unique ID of each device? Yes, several ways—some of them are listed on a page at the Electronics and Robotics site.

• "Consistent Overhead Byte Stuffing" by Stuart Cheshire and Mary Baker, 1999.
• Internet Technologies/Protocols
• "Good RS232-based Protocols for Embedded to Computer Communication"
• "Networking, Protocols, and Devices" forum [3]