Ward Christensen developed XMODEM, a straightforward file transfer protocol, in 1977. It frequently finds application between two computers employing the XMODEM protocol. The protocol initiates transmission with the ‘C’ character, followed by packets. The receiver provides proper acknowledgment (ACK) for each packet. Identification of the last packet is facilitated by EOT, and the completion of transmission is signaled by ETB.
Archives
Embedded Protocol – Bluetooth
Bluetooth is a wireless personal area network(WAN). BLE acronym for Bluetooth Low Energy. One of the most popular short-range wireless communication standards. Known as IEEE 802.15.1, it is now maintained by SIG (Special Interest Group). this is everywhere. How many this devices are there in the room? Cellphones, wireless mouse/keyboard, smart watch/bracelet, earphone, ibeacon.
Embedded Protocol – HTTP
FAQ
- http is tcp or udp?
- http only works TCP
Embedded Protocol – WiFi
WiFi, short for “Wireless Fidelity,” is a technology that allows devices to connect to the internet or communicate with each other wirelessly using radio waves. It’s widely used in homes, businesses, and public spaces to provide internet access without the need for physical wired connections. WiFi operates within the unlicensed radio frequency bands, typically 2.4 GHz and 5 GHz, and it’s governed by the IEEE 802.11 family of standards. These standards define different WiFi versions, such as 802.11n, 802.11ac, and the latest, 802.11ax (Wi-Fi 6), each offering various speeds, range, and features. WiFi routers and access points transmit signals that devices like smartphones, laptops, tablets, and smart home gadgets can receive, enabling them to access the internet or network resources.
Embedded Protocol ZigBee
ZigBee is a low-power, low-data-rate wireless communication embedded protocol based on the IEEE 802.15.4 standard. It is commonly used for creating networks of low-power devices in applications such as home automation, industrial control, and smart energy management.
ZigBee is designed to be simple, cost-effective, and reliable, making it ideal for use in battery-powered devices that need to communicate over short distances. It uses a mesh networking topology, allowing devices to communicate with each other directly or through intermediate nodes in the network.
ZigBee supports a range of applications including lighting control, HVAC control, security systems, and remote monitoring. It provides robust security features to ensure the confidentiality and integrity of data exchanged between devices.
Overall, ZigBee is a popular choice for building wireless sensor networks and other low-power, low-data-rate communication systems.
Advantages of ZigBee:
- Low power consumption: ZigBee is designed for low-power devices, making it ideal for battery-powered devices that need to operate for long periods without frequent battery replacements.
- Low data rate: ZigBee is optimized for applications that do not require high data transfer speeds, making it suitable for applications such as home automation and industrial control.
- Robust mesh networking: ZigBee’s mesh networking topology allows for reliable communication even in challenging environments with obstacles and interference.
- Cost-effective: ZigBee is a cost-effective solution for building wireless sensor networks and other low-power communication systems.
- Security features: ZigBee provides strong security features to protect data communication between devices, ensuring confidentiality and integrity.
Disadvantages of ZigBee:
- Limited data rate: ZigBee’s low data rate may not be suitable for applications that require high-speed data transfer, such as video streaming or large file downloads.
- Limited range: ZigBee’s range is typically limited to a few tens of meters, which may not be sufficient for applications that require long-range communication.
- Interference: ZigBee operates in the crowded 2.4 GHz frequency band, which can be prone to interference from other wireless devices operating in the same frequency range.
- Scalability: While ZigBee supports scalable networks, managing large networks with hundreds or thousands of devices can be challenging.
- Compatibility: ZigBee devices may not be compatible with devices using other wireless communication protocols, limiting interoperability in mixed-device environments.
Zigbee Protocol Analyzwer
Embedded Protocol – CAN
CAN, short for Controller Area Network, was developed by Robert Bosch. This protocol facilitates half-duplex communication. In active voice, it would be: “It operates as a multi-master protocol, allowing it to connect multiple nodes.” This protocol utilizes a two-wire configuration, consisting of CAN H (H-High) and CAN L (L-Low). In active voice, it would be: This two-wire bus interconnects all nodes within the network. The wires typically constitute a twisted pair with a nominal impedance of 120 Ω. CAN supports communication over relatively short distances, typically up to 40 meters at speeds of 1 Mbps
Embedded Protocol – UART
UART (Universal Asynchronous Receiver/Transmitter) is a standard communication protocol used for serial communication between devices. It’s commonly employed in embedded systems for communication between microcontrollers, sensors, and other peripheral devices.
In the context of embedded systems, UART is often used as a hardware communication protocol, enabling devices to transmit and receive data serially. The UART communication involves two pins: TX (transmit) and RX (receive).
- It’s is full-duplex communication
- UART contains a shift register
- which is the fundamental method of conversion between serial and parallel forms.
- Type of Communication: Asynchronous (No clock).
- Rule: The transmitter and receiver should same baud rate. Data format and transmission speed are configurable.
- UART Uses serial communication over a computer or peripheral device serial port. (Electronics Devices).
Embedded Protocol – SPI Communication
SPI is an abbreviation for Serial Peripheral Interface, which stands for Synchronous Serial Communication Interface. It is utilized for short-distance communication and was developed by Motorola in 1980, later becoming a de facto standard. SPI communication operates in full-duplex mode. It is also sometimes referred to as the Four-Wire Serial Bus (FWSB), distinguishing it from Three, Two, and One Wire Serial Bus protocols. The four-wire protocol includes SCL, SS, MISO, and MOSI. SPI operates as a single master protocol.
Embedded Protocol – MQTT
Message Queue Telemetry Transport (ISO/IEC PRF 20922), or MQTT, is a lightweight protocol designed for machine-to-machine (M2M) device communication using a Publish/Subscribe pattern. It was developed by Message Queue Telemetry Transport (ISO/IEC PRF 20922) and Lightweight protocol for (M2M) device communication using Publish/Subscribe. It was Developed By Andy Stanford-Clark (IBM) and Arlen Nipper (Eurotech; now Cirrus Link) in 1999. Unlike HTTP, which follows a request/response paradigm, It utilizes a publish/subscribe architecture. The central communication point in It is the Broker. It is available for implementation in C, C++, JavaScript, Lua, Python, and soon in C#.
Client functions
| Field | Description |
|---|---|
| Host | Address of the MQTT broker. |
| Port | Default: 1883. |
| ClientID | Unique client identifier. |
| Username | UTF-8 encoded string for authentication. |
| Password | Client’s password if flag set. |
| Keep Alive | Duration client stays connected (seconds). |
| SSL | Indicates SSL/TLS encryption usage. |
| Clean Session | If set, session clears subscriptions and messages. |
| Last-will Topic | Topic for “Last Will” message on disconnect. |
| Last-will QoS | Quality of Service for “Last Will”. |
| Last-will Retain | Retain status for “Last Will” message. |
| Last-will Message | Content of “Last Will” in case of disconnection. |
| Topic | Message destination hierarchy. |
| + Plush sign | Single-level wildcard in subscriptions. |
| # Hash Sign | Multilevel wildcard in subscriptions. |
| Publish QoS | Quality of Service levels: |
| QoS(0) – At most once | |
| QoS(1) – At least once | |
| QoS(2) – Exactly once | |
| Retain | Message retention by broker. |
| Subscriptions | List of subscribed topics. |
| Message | Payload data transmitted. |
| Broker | Server distributing messages. |
| Client | Device or app connected to broker. |
| Quality of Service | Message delivery guarantee. |
| Retained Messages | Broker-stored messages for new subscribers. |
| Persistent Session | Broker-maintained session after client disconnects. |
| Last will and Testament and SYS topic | Client’s “Last Will” message and system topics interaction. |
PHP MQTT
Web Apps
WordPress Plugin
DIOT SCADA with MQTT By Ecava
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DIOT which stands for Decoupled IOT, has its SCADA functionalities decoupled into Host and Node for flexibility and scalability that catered for IoT era. This plugin functions as the SCADA Host to work with your device or system, which will be treated as SCADA Node. You just need to enter the broker/server into the configuration. You may then subscribe to the desired topic with a shortcode to display in any desired web page or post. [diot topic="building/floor/device/sensor"] Or, if you have a JSON content, you may add dollar sign as JSON root: [diot topic="building/floor/device/sensor$json.data"]. The content will be updated dynamically when the device publish any data. You may also choose to display your realtime data in trending chart. Check out Ecava DIOT online demo to see how easy things can be done now! For more see here : https://wordpress.org/plugins/ecava-diot-scada/
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WP-MQTT By Roy Tanck
Setting up Tthis is easy. Simply supply your MQTT broker’s details and configure which WordPress events should trigger messages. “MQTT is a machine-to-machine (M2M)/”Internet of Things” connectivity protocol. It was designed as an extremely lightweight publish/subscribe messaging transport.” (from mqtt.org) A number of events are predefined. Simply check the right checkbox and fill in the message’s subject and text.
- Pageview
- User login
- Failed user login
- Post published
- Page published
- New comment
Other events can be added using the “custom events” section. This allows you to use any WordPress hook (actions and filters) to trigger messages.
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Android App
Check this below name in Play-store
- Dashboard
- IOT Manager
- IOT
Broker Service Supporter
The following list of brokers may be used online or locally also giving free and paid service
Adafruit IO (Online – Free)
- Website : Adafruit IO
- Adafruit supporting online free service.
- You can use adafruit client libraries to Python, Node JS, Rubby and Arduino. see the client libraries section).
- The following details are to connect a client to Adafruit IO.
- Host : io.adafruit.com
- Port : 1883 or 8883
- Username : Your adafruit account username
- Password : Your adafruit IO Key
CloudMQTT (Online -Free and Paid)
- Website :
- CloudMQTT
- Online – Free Plans : Cute Cat and
- Paid Plans : Keen Kola, Loud Leopard, Power Pug)
- Using Amazon Web Service
- Type : mosquitto
HiveMQ (Online -Free and Paid)
Connect to Public Broker
- Dashboard
- Broker: broker.hivemq.com
- TCP Port: 1883
- Websocket Port: 8000
- Web socket Client : http://www.hivemq.com/demos/websocket-client/
- Broker: broker.mqttdashboard.com
- TCP Port: 1883
- Websocket Port: 8000
Setup local instance
- Genral Download HiveMQ
- Arun Requested : Downloaded Link
m2m
Free public broker service
- q.m2m.io
- Broker: q.m2m.io
- Port: 1883.
- Application : Facebook messenger
Mosquitto (Local and Online free)
Eclipse Mosquitto™ is an open source v3.1/v3.1.1 Broker.
Free public Service
- iot.eclipse.org
- Broker: iot.eclipse.org
- Port: 1883, 80(WebScoket), 443 (WebSockets+SSl)
- mosquitto
- Broker : test.mosquitto.org
- Port:
- 1883 : MQTT, unencrypted
- 8883 : MQTT, encrypted
- 8884 : MQTT, encrypted, client certificate required
- 8080 : MQTT over WebSockets, unencrypted
- 8081 : MQTT over WebSockets, encrypted
- 80(WebScoket), 443 (WebSockets+SSl)
rabbitMQ
- https://www.rabbitmq.com/
- Install on windows
- Download rabbit for windows :
- Installation guide
Free public broker service
- dev.rabbitmq.com
- Broker: dev.rabbitmq.com
- Port: 1883,
SimpleML
- Free MQTT service to evaluate Machine Learning models, documentation
Free public broker service
- simpleml
- Broker: mqtt.simpleml.com
- Port : 1883 (MQTT), 8883 (MQTT +SSl), 80(REST), 80(WebSockets), 5683 (CoAP)
Other free public broker service
- dioty.co
- Broker : dioty
- Port : 1883 (MQTT), 8883 (MQTT +SSl), 80(REST), 8080(WebSockets), 8880 (WebSocket +SSL)
- swifitch.cz
- Broker :mqtt.swifitch.cz
- Port : 1883 (MQTT)
Interview Questions
Reference
- hivemq
- wiki
- http://www.hivemq.com/ (Tutorials)
- https://github.com/mqtt/mqtt.github.io/wiki
- https://github.com/mqtt/mqttorg-graphics
- github
- http://mqtt.org/
- http://mosquitto.org/download/
- https://www.youtube.com/watch?v=fwb5YAPzPGk
Embedded Protocol – COAP
COAP, or Constrained Application Protocol, a specialized web transfer protocol, is designed for constrained devices and low-power, low-bandwidth networks commonly found in Internet of Things (IoT) and Machine-to-Machine (M2M) applications. CoAP is an application layer protocol similar to HTTP but optimized for constrained environments.
Read more: Embedded Protocol – COAPThis, designed to be simple and lightweight, is ideal for resource-constrained devices, operating over UDP instead of TCP to reduce complexity. It supports request/response interactions like HTTP and offers features such as multicast support and resource discovery. CoAP facilitates efficient communication between constrained devices and web servers, fostering the development of scalable IoT solutions.
Getting Started with Terminal by Br@y tool
- Terminal is a simple serial port(COM) terminal emulation program
- Used for communication with different devices (Modem, routers, embedded uC systems, GSM Phones. GPS Modules)
- Very useful debugging tool for serial communication applications
Embedded Protocol – I2C
I²C (Inter-Integrated Circuit) is a bi-directional two wires and serial data transmission communication protocol developed by Philips (Now NXP Semiconductor) in 1982. I2C is a Half-duplex communication protocol – (I2c can’t send and receive same time in the bus-data line). Multi-master can communicate with multi-salve. (Note: Communication is restricted between two masters; however, a single master can communicate with either a single slave or multiple slaves.) I2C is a Level Triggering. A device that sends data onto the bus is defined as a transmitter, and a device receiving data is defined as a receiver.
The bus must be controlled by a master device, responsible for generating the Start and Stop conditions. In contrast, certain devices such as LCDs, EEPROMs, and RTCs function as slaves. It’s important to note that both master and slave devices can operate as either transmitters or receivers. However, the master device plays a pivotal role in determining which mode is activated.