Mumbai University > Electronics Engineering > Sem 6 > Embedded System and RTOS
Following are the two wireless communication means used for embedded system
- Bluetooth is a low cost, low power, short range wireless technology used for data and voice communication.
- Bluetooth operates at a frequency of 2.4GHz using the frequency hopping spread spectrum technique for communication.
- Bluetooth has a physical link part and a protocol part for communication.
- The physical link part is responsible for transmission of data between devices supporting Bluetooth communication. The protocol part is used for defining the rules for communication.
- The Bluetooth enabled device contains a Bluetooth wireless radio for transmission and reception of data. The protocol is implemented on the ‘Bluetooth protocol stack’ which is held by the communication chip.
- Each Bluetooth device has a 48bit unique identification number and packet-based data transfer techniques are used for communication.
- Bluetooth supports point to point and multipoint communication.
- A maximum of seven slave devices can be connected to a single master. This network is known as a piconet. Slaves in this network can connect to other networks. Such interconnection of networks is known as scatternet.
- The Bluetooth protocol defines profiles for communication. This includes the generic access profile for detecting a Bluetooth device, serial port profile for serial communication, file transfer profile for sharing files and human interface device profiles for supporting interface devices like keyboard, joysticks, etc.
- Zigbee is low power, low cost, wireless network communication based on the standard IEEE 802.15.4.
- Zigbee is suitable for low power, low data rate and secure application for wireless personal area networking (WPAN).
- Zigbee supports mesh, start, tree and other networking topologies.
- Zigbee works on the unlicensed spectrum ranging from 2.4-2.48GHz, 902 to 928 MHz and 86 to 868.6MHz.
- It works on an operating distance upto 100m at a data rate of 20 to 250kbps.
As shown in the diagram above, zigbee devices can be classified into 3 categories.
a. Zigbee coordinator: This device is responsible for the creation of the network and for initiation of communication
b. ZigBee Router: It is responsible for routing the data to de=different end-devices across the network.
c. ZigBee End Device: It can only communicate with the ZR or ZC but doesn’t have capability to act as the mediator for transferring data from one device to another.
- Zigbee is used for applications involving wireless sensor networks, industrial automation, home automation, Automatic meter reading, smoke detectors, etc.