There are variety of WiFi-based chipsets that embedded developers and product designers use in their IoT designs. An alternative reference design that allows these developers and designers to explore IoT (Internet of Things) concepts is the cloudBit manufactured by littleBits electronics. The littleBits are colorful electronic modules that provide specific electrical functions for consumer devices and gadgets. By connecting the modules in unique creative ways, interesting, innovative electronic devices and gadgets can be built. The ease in which electronic devices and gadgets can be built allows a rapid approach to developing new IoT design concepts. I’ll present an alternative design approach to building IoT product concepts using the littleBits cloudBit. To illustrate this design method a WiFi-based appliance controller prototype will be built with additional littleBits modules. Before discussing the design details of the IoT appliance controller prototype, I’ll present the system architecture of the cloudBit using block and circuit schematic diagrams.
|The cloudBit, an alternative reference design for IoT concept development. (Source: littleBits Electronics)|
The cloudBit System Architecture
The cloudBit module allows a variety of electronic devices and gadgets to easily connect to a home WiFi network. The IC (integrated circuit) technologies used on the tiny electronic module’s PCB (Printed Circuit Board) allow wireless connectivity to control and monitor other littleBits modules. Also, a hardware development kit (HDK) provides electrical circuit interfacing to non littleBits modules, as well. The cloudBit module’s System Architecture consists of eight basic subcircuits using a variety of SOIC (Small Outline Integrated Circuit), LQFP (Low Profile Quad Flat Pack), and SMD (Surface Mount Device) components. The littleBits System Architecture consists of the following eight basic subcircuits:
- Power Supply
- Setup (pushbutton switch)
- WiFi Dongle (USB Host adapter)
- Analog In
- Analog Out
- μSD (micro SD)
- RGB LED (status)
- 512 MB (Megabytes) DDR-SDRAM (Double Duty Rate Synchronous Dynamic Random Access Memory)
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|The cloudBit System Architecture consists of eight basic subcircuits. (Source: Don Wilcher)|
The cloudBit’s WiFi radio is packaged inside of a USB adapter. Dynamode manufacturers the radio (Part Number WL-700N-XS) which is a compliant 802.11n/g WiFi device. It’s operating frequency range is 2.4- 2.4835 GHZ, which puts the USB adapter within the ISM (Industrial, Scientific, Medical) category of wireless devices. The Dynamode USB WiFi adapter conveniently operates from a single 5V DC source only consuming 0.6W of power.
|The cloudBit WiFi chipset is conveniently packaged into a USB adapter. (Source: Dynamode)|
The linux software that provides the WiFi setup resides inside of the μSD (micro SD card) located on the bottom side of the cloudBit. The RGB LED provides operational and setup status of the cloudBit. The setup button allows the cloudBit to detect and connect to the home network by pressing a tiny momentary switch. The NXP iMX23 processor provides I/O processing of the external connected subcircuits. To aid the iMX23 processor, as a wireless controller, an external 512 MB (Megabyte) DDR SDRAM chip makes high WiFi transfer rates manageable by controlling the digital data and electrical clock signals. The WiFi transfer rate of the DDR SDRAM is supported by 16 address lines, 15 data lines, and 13 control lines. The analog I/O circuits allow electrical wiring of the cloudBit to other electronic modules or developer designed circuits.
|Electronic components supporting the cloudBit WiFi module.
(Source: littleBits Electronics)
To accomplish external circuit interfacing, the littleBits electronic modules include plastic bitSnaps. bitSnaps have three metal pins for electrical connections. The electrical connections consist of the following signal names:
- Vcc (+5V power supply)
- sig (electrical signal)
- gnd (electrical ground)
|The cloudBit physically interacts with other littleBits modules or external circuits using the bitSnap electrical connection scheme. The littleBits modules are mechanically connected with magnets.
(Source: Don Wilcher)
In developing the system architecture block diagram, I used the circuit schematic diagram obtained from littleBits’ github website. A key educational philosophy of littleBits is to open source their design, thereby democratizing electronics for educators, students, inventors, engineers, and makers. Github is the ideal website for promoting their open source philosophy because all of the littleBits module design files are zipped and can easily be downloaded to your machine’s hard drive. Circuit modifications and new modules can be achieved conveniently using these open source files.
The library of littleBits’ module circuit schematic diagrams are created in Eagle CAD software. As seen next, the cloudBit electronic schematic diagram is quite comprehensive in subcircuit details. Also, their design is based on the OLinuXino Nano created by Olimex: another manufacturer of open source embedded development boards.
|The completed circuit schematic diagram of the cloudBit.
(Source: littleBits Electronics)
The Coffee Pot Controller
With the cloudBit system architecture explained, let’s look at how to use it in a WiFi appliance control application. To illustrate the ease in which this IoT device can be prototyped, I’ll briefly discuss the Coffee Pot Controller. This project was presented, with additional hands-on lab projects, in a week-long Design News CEC webinar course titled Prototyping Home Automation Concepts. The project design concept is to control a coffee pot wirelessly using a smartphone, tablet, desktop PC, or notebook computer with a simple UI (User Interface) pushbutton. Touching the pushbutton on a smartphone or tablet will turn on the coffee pot. A mouse click of the UI pushbutton on a desktop PC or notebook computer will accomplish the same task. A system diagram of the Coffee Pot Controller is shown next.
|The cloudBit along with supporting littleBits electronic modules can rapidly build an IoT coffee pot controller. (Source: littleBits Electronics, Don Wilcher)|
Setup instructions to connect the coffee pot controller to your home WiFi network using the cloudBit are found on the littleBits website. Also, the AC switch has an IR (Infrared) sensor that needs to be paired to the IR transmitter. After all wireless connectivity of the cloudBit, AC switch, and IR transmitter components are achieved, the cloud-based UI pushbutton will be able to turn the coffee pot on and off. Beside controlling a coffee pot, small AC home electrical appliances like portable house fans, radios, and TVs can also be operated with this IoT-based controller.
|A coffee pot controller prototype built with a cloudBit (left) and additional littleBits electronic modules. (Source: Don Wilcher)|
I hope the cloudBit features discussed and illustrated with the coffee pot controller can be realized as an alternative prototyping tool for developing new IoT appliances. Additional information about the coffee pot controller project can be obtained from the Day 4 of the Prototyping Home Automation Concepts Design News CEC webinar course. Also, pricing of littleBits cloudBit, electronics modules, projects, and accessory kits may be found on the littleBits website.
Don Wilcher is a passionate teacher of electronics technology and an electrical engineer with 26 years of industrial experience. He’s worked on industrial robotics systems, automotive electronic modules/systems, and embedded wireless controls for small consumer appliances. He’s also a book author, writing DIY project books on electronics and robotics technologies.