With the rise in complexity of end-products, current generation design kits are much more complete than in earlier years. They are RoHS-, FCC- and CE-compliant, with optimized layout and good EMC performance. Plus they come complete and tested with comprehensive suites of software.
At the same time, designers are under increasing pressure to reduce the time-to-market of their products, a trend that will only accelerate as the Internet of Things (IoT) picks up speed.
Figure 1: Freescale mBED development kit for IoT applications. (Source: EDN-Europe)
As a result, businesses and entrepreneurs have begun integrating development boards and components directly into their product designs in an effort to cut down on development time and costs. Development kits are becoming an essential part of the design process. This goes beyond prototyping and testing to using development kits partially or in whole as a reference design or even incorporating these designs into their end products.
A 2014 study of design engineers found that 45 percent of respondents used development kits as part of their designs—primarily for sensing, wireless and communications applications—and of those, 79 percent said they used some portion of the development kit design in their final production design. The research also shows that four out of five of these designs moved through to production in 12 months or less.
Manufacturers of development boards recognize that their systems can offer a quick way to a finished product, or a method to easily add a new function to an existing product. For example, FTDI supplies a range of development modules supporting prototyping and development for their USB devices. The company promotes their development modules as a way to enable USB connectivity within existing product designs.
Other suppliers offer development boards with added features specifically aimed at suppliers who wish to make the development system the basis of a fully-fledged product.
Development Kits for Production Systems: The Pros and Cons
When does it make sense to consider using a development kit as the basis for a design versus designing everything from scratch? Here's a run-down of the pros and cons. First, the pros:
• For one-of-a-kind or very low-volume applications, or projects where the cost of the hardware is a small percentage of the total, then the higher unit cost of the development board can be outweighed by the reduction in development time.
• If certification (FCC, CE, etc.) would be expensive or time-consuming relative to the cost of the hardware, a ready-made development kit might make sense.
• If the unit being built has a lot of custom applications or customers have specific customization requirements, a development kit can reduce development time considerably.
• If you want to add a particular interface—such as ZigBee or Bluetooth—to an existing design, using a ready-made development kit can be the quickest and easiest way to proceed.
On the other hand, using a development kit board has certain disadvantages, such as:
• The higher cost may make a development kit cost-prohibitive for volume production.
• In general, a development kit will have a lower performance-to-cost ratio for a specialized application.
• The hardware might be less flexible in terms of integrated peripherals, I/O, etc.
• A development kit is usually larger in size than a custom board.
• A development kit may be more difficult to integrate (mechanical and electrically).
• The development kit manufacturer isn’t usually set up to supply high volumes in an efficient manner.
• The development kit may be only be available under a license (for instance, this one) that doesn’t adequately protect your intellectual property.
Plan B: Shorten Development Time by Starting with Development Kit Design Files
If you can’t use the development board hardware “as is” out of the box, the next best thing is to start with the design and make the minimum modifications possible. Recognizing this, some development kit manufacturers provide a complete set of design tools to speed the process.
For example, Freescale provides printed-circuit board design files for all Freescale Tower modules. These files can be helpful for an experienced board designer to use as examples when building their own module or a derivative design. The files are provided in professional formats—depending on the particular kit, some or all of the following files are available:
• LAY—Layout source (Cadence Allegro)
• GRB—Gerber files
• FAB—Fabrication document
• UNI—UniCAM file
• CEN—Placement file
• BOM—Bill of Materials
• SCH—Schematic source (Cadence, OrCad)
• SPF—Schematic PDF
Similarly, Microchip’s MRF89XA 8-bit wireless development kit is an evaluation and development platform for sub-GHz application designers. The develop kit includes Microchip’s MRF89XAM9A transceiver module and the PIC18 XLP microcontroller family, enabling designers to rapidly prototype wireless applications. The demonstration kit is pre-programmed with Microchip’s MiWi™ protocol stack and comes with complete Gerber files.
To further help designers, the MRF24J40MA module has received regulatory approvals for modular devices in the United States, Canada and European countries. This allows the end-user to place the MRF24J40MA module inside a finished product and not require regulatory testing for an intentional radiator (RF transmitter), provided no changes or modifications are made to the module circuitry.
It’s Not Only about the Hardware
When making a decision about whether to use all or part of a development kit in your production design, remember that development kits include a lot more than just hardware. Software Development Kits (SDKs) for embedded microcontrollers include numerous software modules: real-time operating systems (RTOS), device drivers, TCP/IP stacks, and more, all of which can drastically reduce development time.
Figure 2: Sitara SDK. (Source: LinuxGizmos)
For instance, the Texas Instruments’ SDK for the Sitara range of processors, which are based around the ARM® A-series of cores, includes:
• Linux Kernel and Bootloaders
• GUI-based application launcher
• File system
• Qt/Webkit application framework
• 3-D graphics support
• Integrated WLAN and Bluetooth® support for selected parts
• ARM benchmarks: Dhrystone, Linpack, Whetstone
• Webkit web browser
• Soft Wi-Fi access point
• Cryptography: AES, 3DES, MD5, SHA
The Sitara SDK can be downloaded for free, requires no runtime royalties and includes Board Support Packages (BSPs), tools, demos, and documentation.
Arrow offers a large number of development kits and tools for both analog and digital application.