Design Con 2015

Cypress kit simplifies Apple-lightning accessory designs

-July 19, 2013

Older accessories for Apple's line of "i" products, such as iPhones, iPads, or iPods, have a 30-pin connector that provides USB, analog audio, display, and power signals for plug-in accessories. The latest "i" devices, though, use a 8-pin "Lightning" connector that includes two USB communication channels and an identification/control signal for each.

To help engineers, programmers, and product designers get a head start on Lightning-compatible designs, Cypress Semiconductor created a new development kit for digital-audio accessories for Apple’s "i" products. The CY8CKIT-033A PSoC 3 MFi Digital Audio Development Kit for Lightning includes license-free reference hardware, firmware, and iOS app software. The Cypress reference design immediately connects an Apple device to a programmable system on a chip (PSoC-3) integrated circuit so designers can go from a concept to an MFi-licensed product within a few months. For kit information, please visit this page. The kit, shown in the image below, also includes an adapter (not shown here) for Apple's 30-pin products.



Accurate reproduction of audio signals delivered across a USB link can cause a design headache. According to information in a Cypress white paper, "Designing Modern USB Audio Systems," a device that received digital audio over a USB interface requires a master clock. That clock should synchronize the audio sample rate with the proper conversion back to analog audio. USB provides no such clock signal, so the engineers at Cypress created a USB audio clock synchronization and recovery scheme compatible with the PSoC-3 chip. Thus the reference design can ensure bit-perfect audio at several standard sample rates for speaker docks, headphones, game controllers, microphones, MIDI controllers, and so on.

The CY8CKIT-033A kit works with any Core Audio or Core MIDI (Musical Instrument Digital Interface) iOS app, including Apple’s GarageBand, and music streaming apps such as Pandora and Spotify. To get development work started quickly with the Apple External Accessory (EA) framework, the kit comes with Cypress’s EA Console example iOS app, that enables bidirectional communication between apps and accessories attached to an Apple device. The EA Console, for example, can deliver firmware upgrades from the Apple device to a connected accessory.

The PSoC-3 MFi Digital Audio design includes Cypress’s CapSense technologies that let you easily create touch-sensing buttons and sliders, and proximity sensors that enhance a user interface and aesthetic appeal. For more information about the kit or to view a demonstration, please visit this page.

Licensees of Apple's MFi program may purchase the CY8CKIT-033A PSoC 3 MFi Digital Audio Development Kit for Lightning from Apple’s authorized MFi component distributor. Price: $199. Click here for information about the Apple MFi program.

Before engineers or programmers use the MFi development kit, they must download the free PSoC Creator and PSoC Programmer software from the Cypress website. I have enjoyed using these programs because they let me quickly move all-in-one building block diagrams into a design window for functions such as serial ports, filters, op amps, analog converters, touch controllers, display controllers, and so on. Then I connect the functions as needed and include any code for the 8051 microcontroller core in a PSoC-3 chip. The MCU enhances the functions and provides the capability to program many operations, controls, displays, data transfers, and communications, among other things. For PSoC software, lists of functions, sample projects, and other information, please visit this page.

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