Mobile Devices: Developing Applications for the Smart Accessory Revolution


The mobile computing device market has been one of the fastest-growth sectors the electronics industry, and the pace shows no signs of slowing. Market watchers agree that this explosive growth is set to continue into 2020. Driving this growth is a potent combination of mobile broadband connectivity, combined with increasingly powerful mobile computing capability. High-resolution displays and intuitive user interfaces have also changed the landscape for the consumer electronics market, making it possible to combine a multitude of functions that up to now have been performed by separate, stand-alone products.

The flood of new smart devices has also created the demand for new smart accessories, interfacing to the mobile devices and using them as personal connectivity hubs. In the consumer’s mind, accessories are no longer limited to ear buds and chargers.

The key to translating the idea for a new smart accessory into a product in a timely fashion is a comprehensive development infrastructure. This includes a portfolio of development products and tools, together with stable and mature software libraries. The ideal development platform provides the basic elements of a design, while not restricting freedom for those bringing the next must-have accessory to market. Uniquely, Microchip can offer this design environment – for all levels of PIC® microcontrollers, plus analog and wireless components – for both Apple and Android™ platforms.

Designing an Accessory
Mobile device accessories can take many forms, depending on their connectivity and power sources. For example:

  • Accessories may draw power independently from an AC wall socket, and communicate with mobile devices over physical connections. USB is a common protocol of communication. These are typically “docked” accessories such as audio playback sub-systems or DJ music mixers.
  • Accessories may draw power from mobile devices, and communicate over physical connections. They are typically portable accessories such as glucose meters, pico-projectors or credit card readers.
  • Accessories may communicate with mobile devices wirelessly. Common wireless protocols include Bluetooth (or its low-power variant, Bluetooth LE) and Wi-Fi®. These accessories may draw power either from batteries, AC wall socket or other external supply, and may be docked or portable such as pedometers, home automation panel controls, or auto diagnostics.

Accessory designs also vary greatly in complexity. For designs that use microcontrollers, the range spans connectivity products that are (in effect) “smart cables”, to audio playback docks and encrypted financial devices. The design effort that must be invested in an application will vary correspondingly. In all cases, there will be a hardware phase (MCU choice and configuration), a firmware phase (establishing connectivity and communication protocols), and finally the software application phase (designing the application on the mobile device).

Regardless of its ultimate form, a key requirement in designing any accessory is to satisfy the user experience. The consumer’s expectations are set by those of the host mobile device: the accessory must match or even exceed those expectations. Everything that contributes to a consumer product’s brand values – ease of use, utility, appearance – combines to determine user satisfaction. The designer’s choices in efficient user interfaces or fast response time all influence the user experience.

Examples of Microchip Development Platforms
Microchip’s Smartphone accessory development portfolio comes with highly refined hardware development boards and an extensive set of software libraries. The hardware development boards come with complete reference design information. The included Gerber files that allow entire boards, or sections of boards, to be used as the basis for fast time-to-market product turnaround of both high fidelity audio and nonaudio accessories. Use of standards in development boards goes beyond the obvious connections to Apple iOS or Android-based devices. For example, the 16/32-bit MCU Accessory Development kit might become the basis of a GPS car kit for an iPhone.


Additionally, the development platform provides connectors for expansion capability so the developer can quickly add to a prototype, pre-configured hardware and functions from that product space. Those working with Apple devices will find the appropriate connector to directly connect iPod, iPhones or iPads, either directly on the development board for lower-complexity designs, or on a plug-in expansion card for more advanced devices.

For either development platform the designer can select from an extensive software library of proven functional blocks for a wide range of application domains. Software comes royalty-free and no-feelicense and is maintained to be compatible with the latest Apple iOS or Android releases. Designers can also call on a suite of basic functional code blocks to build the framework of designs in an almost limitless array of application spaces. The software library elements also feature automatic initialization and allow for field upgradeability over wired or wireless connections, ensuring continued compliance with evolving standards for accessory products.

Microchip’s PIC24 or PIC32 Accessory Development Starter Kit for Android gives designers all they need to get their accessory project talking to, and exchanging data with Android devices. The platform provides a library for accessing and talking to Android devices through the Open Accessory Framework found in the Android OS (versions 2.3.4 or 3.1 and later). The free download comes with examples that show how to connect and communicate over the open accessory framework via USB embedded host and On-the- Go. Firmware examples show how to complete the design using the Android accessory library, linking the hardware portion of the design to the application.


Microchip’s 16-/32-bit Accessory Development Platform for Made-for-iPod, available through the Apple distribution channel, provides has an equally comprehensive offering for the Made-For-iPod (MFi) program.

The audio space is particularly well-served, with a full suite of functions covering audio input and output, audio processing, filtering and mixing. At the top of the range, the PIC32 Digital Audio Playback Development Kit provides a cost effective audio docking solution with on-chip SRC, up to 32-bit sampling at 48 kHz, and encoding/decoding to all commonly-used digital format. The MIDI Accessory Development Kit will run MIDI input and output, while powered by the iPhone or iPad.

As mobile devices become mainstream, the technology hub around which consumers organize their lives and the scope for innovative accessories is limited only by the imagination of design teams. Microchip’s Smartphone development platforms allow designers to stretch their imagination to the fullest.

For more information visit:

Contact Information

Microchip Technology Inc.

2355 W. Chandler Blvd.
Chandler, AZ, 85224

tele: 480.792.7200
toll-free: 888.MCU.MCHP
fax: 480.792.7277

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