Mumbai University > Electronics Engineering > Sem 6 > Embedded System and RTOS

Following are the two wireless communication means used for embedded system

Bluetooth:

1. Bluetooth is a low cost, low power, short range wireless technology used for data and voice communication.
2. Bluetooth operates at a frequency of 2.4GHz using the frequency hopping spread spectrum technique for communication.
3. Bluetooth has a physical link part and a protocol part for communication.
4. 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.
5. 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.
6. Each Bluetooth device has a 48bit unique identification number and packet-based data transfer techniques are used for communication.
7. Bluetooth supports point to point and multipoint communication.
8. 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.
9. 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:

1. Zigbee is low power, low cost, wireless network communication based on the standard IEEE 802.15.4.
2. Zigbee is suitable for low power, low data rate and secure application for wireless personal area networking (WPAN).
3. Zigbee supports mesh, start, tree and other networking topologies.
4. Zigbee works on the unlicensed spectrum ranging from 2.4-2.48GHz, 902 to 928 MHz and 86 to 868.6MHz.
5. It works on an operating distance upto 100m at a data rate of 20 to 250kbps.

6. 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.

7. Zigbee is used for applications involving wireless sensor networks, industrial automation, home automation, Automatic meter reading, smoke detectors, etc.