There are literally dozens of short-range wireless technologies to choose from when implementing home appliances. These are part of a broader movement of monitoring and controlling almost anything generally known as the Internet of Things (IoT). Home appliances are just one segment.
Besides the popular Wi-Fi and Bluetooth (BT) standards discussed in Part 1 of this article, designers can select other standards like Zigbee, Z-Wave, and multiple IEEE 802.15.4 versions. Nevertheless, designers have zeroed in on Wi-Fi and BT for home appliances. Even within those two standards, one can choose from among multiple versions. One approach making that design decision easier is the availability of both Wi-Fi and BT radios on a single chip. First, let’s review and compare the individual standards.
Bluetooth Summary
Bluetooth (BT) is a short-range, point-to-point wireless technology using the 2.4-GHz ISM band meant for building personal area networks (PANs). Invented by telecom vendor Ericsson in 1994, Bluetooth is managed by the Bluetooth Special Interest Group (SIG). Multiple versions are available:
BT 1.x: This nearly extinct version allowed Bluetooth communication to go up to a theoretical maximum of 1 Mb/s, called basic rate (BR).
BT 2.x: This version added the option of an extended data rate (EDR) of 3-Mb/s throughput.
BT 3.x: This version introduced the option of sending data over alternate layers to achieve high-speed (HS) data rates.
BT 4.x: The 4th generation of the Bluetooth spec made a radical change and introduced Bluetooth Low Energy (BLE), which is meant for very low data rates and operates at extremely low power. While the symbol rate has been limited to 1 Mb/s vs. 3 Mb/s EDR, power consumption has been reduced to at least half or even lower compared to BT classic. BLE also offers an improvement in the latency from going from a non-connected state to sending data. For BT classic, this latency has been 100 ms+. BLE reduces it to <6 ms. Devices that support the optional LE feature are only non-backward-compatible to older BT generations. These are called BLE or Bluetooth Smart devices. Devices that support both BT classic rates and BLE are called Bluetooth Smart Ready.