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