Designing High Performance GUIs

329 Brumby Lead Image for Web

UIs for the Multicore Era

For embedded developers, it’s critical to understand the types of performance problems a typical end-user might encounter and the performance metrics relevant to user
interface (UI) design. Phil examines these and other important UI design challenges.

By Phil Brumby
Mentor, Embedded Systems Division

The widespread proliferation of portable media devices has changed the way we interact with each other on a daily basis. In fact, there is now a generation of users who grew up with some type of touchscreen device. These users no longer see the UI as new or revolutionary, but rather as a standard piece of mobile device functionality. This phenomenon has created a new set of expectations. It means any device with an LCD must offer a fluid and intuitive user experience. It’s also expected that the touchscreen has to be “smartphone-like” whenever the device is powered on. Embedded system developers are now under pressure across multiple markets and device types to replicate the smartphone UI interactive experience.

The importance of getting the UI right is absolutely critical to the success of the device. Underpinning documented UI design methodologies is a need for the device to operate in a way that it will not impinge or be detrimental to the user experience. For developers, it’s necessary to understand the types of performance problems a typical end-user might encounter, and through an understanding of performance metrics employ various analyses to highlight the bottlenecks and performance degradation issues.

A key advantage to system start-up is analyzing selected input events.

A key advantage to system start-up is
analyzing selected input events.

TYPICAL PERFORMANCE ISSUES

To understand how to best analyze performance, it’s important to look at typical performance issues from the end-user’s perspective. In identifying these issues, developers can begin to identify the first data points or metrics needed for feedback on system performance.

Responsiveness: Responsiveness can be thought of as the time it takes for the user to receive feedback from the UI as a result of an input action made. Typically, this consists of a touchscreen input, but also includes hard key presses. Responsiveness is important as the user must feel the device performs within a certain timeframe to avoid the feeling a UI is “laggy” or slow to respond. Delays in updating the UI in response to input can result in frustration and mistakes made by the user.

Animation smoothness: Animation smoothness relates to the visible motion or change in appearance of elements displayed within the UI. As an element transitions from one point in 3D space to another, does it do so in a smooth manner that is pleasing to the eye? Animation smoothness is important because if the user perceives jagged or staggered motion in a transition, it will degrade the overall interactive experience.   …

Read the full article in the December 329 issue of Circuit Cellar

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Buck Converter Extends Battery Life of USB Type-C Gear

Maxim Integrated Products has announced the MAX77756, a 24 V, 500 mA, low quiescent current (IQ) buck converter. The product targets developers of multi-cell, USB Type-C products in need high current, dual inputs and I2C support. USB Type-C products must generate an always-on 3.3 V rail to detect USB insertions. Products utilizing the Power Delivery (PD) voltage range (5 V to 20 V) can generate an always-on (1.8 V /3.3 V /5.0 V) digital supply MAX77756_EVKit_imagerail for the port controller using the MAX77756 step-down converter. In addition, the MAX77756 has a 2 0 μA quiescent current that extends battery life by reducing idle power consumption. To simplify the system design, the MAX77756 has a dual input ideal diode ORing circuit that allows the chip to power from the external USB source if the battery is empty.

Multi-cell battery-operated devices—such as ultrabooks, laptops, tablets, drones and home automation appliances—can easily evolve to Type-C with PD using the flexible MAX77756 power supply. The MAX77756 has a unique combination of wide input voltage range, low quiescent current, higher current load, dual input, and I2C for flexibility and programmability. There is also a default power mode if customers do not want to use the I2C bus. The MAX77756 is a robust IC with short-circuit and thermal protection, 8ms internal soft-start to minimize inrush current, proven current-mode control architecture, and up to 26V input voltage standoff.

Key Advantages

  • Low quiescent current: 1.5 μA Buck and 20 μA MUX for always-on operation
  • High efficiency: Up to 92% with integrated power MUX
  • Small solution size: 2.33mm x 1.42mm 15-bump WLP; no external Schottky array needed
  • Wide input voltage: Operates on full VBUS range (5 V – 20 V) and VBATT (2S, 3S, 4S Li+)

MAX77756 is available from stock and priced at $0.65 (10,000+)..An evaluation board MAX77756EVKIT# (see photo) is available from stock and priced at $70

Maxim Integrated Products | www.maximintegrated.com