Interface. RF modules typically communicate with an embedded system such as an MCU or microprocessor. Communication protocols include UART used in Digi International’s XBee modules, Serial_Peripheral_Interface_Bus used in Anaren’s AIR modules and USB used in Roving Networks’ modules. Although the modules may use a standardised protocol for wireless communication, commands sent over the MCU interface are typically not standardised, as each vendor has its own proprietary communications format.
Speed of the MCU interface depends on the speed of the underlying RF protocol used—higher speed RF protocols such as Wi-Fi require a high-speed serial interface such as USB, whereas protocols with a slower data rate such as Bluetooth Low Energy may use a UART interface.
IoT-driven modules. Embedded electronic devices are now adding the capability to be accessible from the Internet or be able to push data to the Cloud. This new trend in connecting smart electronic devices to the Internet is called the IoT. Many research studies have envisioned that 20 to 50 billion smart devices or things will be connected to the Internet by 2020. Attractiveness of the IoT market is driving the creation of many new businesses.
Main hardware components of an IoT device are:
Microcontroller unit. The processing unit together with the memory device
Connectivity module. Wireless or wired connectivity module enabling the device to communicate with other devices
Sensor module. Temperature, proximity, movement, humidity, current, voltage and so on
As in any design activity, there are several approaches to designing IoT hardware and devices like chip design solution, SoC design solution and embedded module solution. To avoid the risk of failure and project delays, many companies go with the module path. That does not mean that they are engaged in an easy path.
Wireless module selection is another challenge. Ambedkar says, “IoT-driven Wi-Fi modules connect a sensor or end node device directly to the Internet. These require a router in order to upload collected data to the Internet. Issues faced by such modules usually include limited penetration power, inefficient mesh network and lack of a standard protocol like ZigBee. On the other hand, these modules are relatively cheaper and can be accessed using mobile phones and tablet PCs, thus giving a better option for user touch points.
“IoT-driven RF modules connect to a gateway device and transmit data to it. The gateway then uses an appropriate connection backbone like GPRS, Wi-Fi, WiMAX or Ethernet in order to upload data to the Internet. Issues faced by these modules include an additional intermediary to upload data like a gateway and higher cost than Wi-Fi modules.
“However, both types of modules have a higher range and better penetration than Wi-Fi. Coupled with an efficient mesh protocol, RF modules find applications in all smartcity domains like smart metering and smart lighting.”
He adds, “In the Asian scenario in general and the Indian scenario in particular, solutions should use a combination of technologies. As mentioned earlier, concrete obstacles are aplenty and Internet connectivity is patchy in some areas. This calls for a solution that has an RF mesh to collect data from devices like utility meters, lighting fixtures and home sensors. This mesh would then transmit data to a gateway device. Using an appropriate connection backbone like Wi-Fi, Ethernet, WiMAX or GPRS, the gateway will then upload data to the Internet. The gateway device and RF modules need to be able to work even in the absence of Internet connectivity to ensure that the solution is not Internet-dependent.”
Praveen Ganapathy, director – embedded processing, India sales and applications, Texas Instruments India, adds, “We see broadest traction for BLE across segments, followed by Wi-Fi for home and enterprise segments, followed by sub-GHz radios with support for Zigbee, 6LowPAN and more in the industrial space. Near Field Communication is also seeing increased traction in payments, pairing and related applications involving authentication.”
Anand informs, “All Wi-Fi and RF modules are IoT-centered these days. However, not all fit due to the fact that some criteria do not match. For example, both NodeMCU and smartWi-Fi module are based on the same chipset, however, smartWi-Fi has a battery charger and a user button, LED on board, while NodeMCU does not, that makes the final setup much bulkier.”
