Obsolescence-Proof Your UI (Part 1)

(Photo 1)
Web Server Strategy

After years of frustration dealing with graphical user interface technologies that go obsolete, Steve decided that web browser technology could help this problem. With that in mind, he built a web server that could perform common operations that he needed on the IEEE-488 bus—and it is basically obsolescence-proof.

By Steve Hendrix

My consulting business is designing custom embedded electronics. Many such systems are size-constrained, but still need some type of user interface. For portable devices, the battery is usually the biggest point of discussion. For wireless designs, it’s the antenna. But for virtually every design, the user interface figures prominently in the concept discussions.

I’ve been involved with one particular design for some 20 years now. When I took it over from the client’s in-house designer, the internal structure was very shaky. Unfortunately, they were not willing to change it due to the re-certification efforts that would be required for a major change. The design’s user interface used a graphic LCD with a touchscreen overlay. I have just completed the latest revision to replace an obsolete part—the latest in a long series of revisions caused by the display panel or the touchscreen going obsolete. This usually happens just about the time the whole product gets through final certification. In this case, we jumped through a lot of hoops to avoid disturbing the core of the product so we wouldn’t require a a big recertification effort. We did so by building a daughterboard that emulates the original touchscreen. A web browser interface would be so much easier!

In a similar vein, I recently purchased a spectrum analyzer to replace a failed unit. The only way to get a screen dump into my PC is via the IEEE-488 bus. That standard is sometimes known as GPIB (General Purpose Interface Bus) or HPIB (Hewlett-Packard Interface Bus). Because this bus has mostly fallen out of favor, instruments that use it are inexpensive. The solutions that purport to interface the IEEE-488 bus to a PC are themselves badly dated. In addition to requiring a cable big enough to flip an instrument off the bench, several other pieces are needed. You need to buy a board that goes inside the PC for four figures, and software to run it for well up into four figures, and hope your PC and operating system are old enough to be compatible. Alternatively, numerous USB interfaces are available. All of those interfaces require a custom driver in your PC, and most of those drivers require older versions of Windows.

Photo 2
(a) A close-up view of the finished unit, which fits comfortably within a standard IEEE-488 connector backshell. This unit is ready for the final application of the label showing its permanently-assigned MAC address. (b) A peek under the hood, showing the microcontroller, the IEEE-488 bus termination resistor packs, and most of the power supply. The mini-USB connector makes no data connection, but only provides power to the unit. Such power supplies have become such ubiquitous commodity products that they are the most cost-effective way to get 5 V power to the unit.Many years ago, I worked for a company who specialized in IEEE-488 interfaces. Although I’d forgotten some of the nuances that make it such a pain to work with directly, I remembered enough to know that the Microchip PIC18F97J60 microcontroller could directly drive the bus lines for a single instrument. The PIC would need buffering to deal with the full 14 instruments that can be on the bus per the specification, but I just wanted to interface a single instrument. Best of all, I already had experience with building a web server in this chip from my solar power controller discussed in the July 2014 and August 2014 issues (Circuit Cellar 288 and Circuit Cellar 289.) The microcontroller and all required electronics could fit inside the backshell of a standard IEEE-488 connector. The lead article photo (Photo 1) shows the very tidy end result—note the MAC addresses printed on each label. Photo 2 shows a close-up view of the exterior and interior.

I’m sure that HTTP and web browsers will someday go the way of buggy whips. However, given their use today in everything from PCs to laptops to tablets to smart phones, I’m thinking web browsers are likely to be around for a while. With that in mind, I chose to build a web server that could perform common operations that I need on the IEEE-488 bus, and ultimately built it into a product available for sale to others with similar needs. By using a web browse the user interface, the device is accessible via anything from a desktop computer to an iPod—and it’s pretty much obsolescence -proof, at least within my lifetime! …

Author′s Note: I offer a special discount on KISS-488 to Circuit Cellar readers. Contact me at SteveHx@HxEngineering.com for details!

Read the full article in the April 333 issue of Circuit Cellar

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Programming-Free LCD User Interface for Embedded Applications

LCDTERM.com recently launched a new programming-free LCD user interface, which allows for seamless and code-free integration onto any embedded platform. Eliminating the need to write software to control the display, the LCDTERM user interface does not require LCD programming knowledge, so you can focus more on desired functionality rather than writing device drivers. Its three-button keyboard allows developers to implement a full user interface without having to worry about reading buttons, debouncing, or programming resources on the host embedded system.LCD term

The LCDTERM interface includes all control firmware and uses a speedy ARM M0 processor. It comes with a free API. Included font and user-defined bitmaps allows for addition of 64K color displays to any embedded system. Display sizes begin at 1.77″ and are ready to ship immediately in high quantities. Larger sizes of 2.8″ and 5″ are also available. LCDTERM.com can scale for custom sizes, and it is equipped to enter into OEM arrangements. Free demo kits are available for applications via the website.

Source: LCDTERM.com

Bluetooth Low Energy Changes the “Wireless Landscape”

In 2010, the Bluetooth Special Interest Group (SIG) took Nokia’s existing Wibree standard and renamed it Bluetooth Low Energy (BLE). In doing so, it combined the latest in a series of evolutionary engineering improvements with brute-force market pressure to change the wireless landscape.

Adding BLE to the Bluetooth 4.0 specification has spurred rapid adoption. In fact, the SIG predicts that 90% of Bluetooth-enabled smartphones will support BLE by 2018. Before this wide adoption, a Wibree-based product had to include both sides of the radio link. Now a BLE-based device can ship with the assumption that the customer already owns the receiving half. This enables system architects to consider the user interface (UI) to be a software problem, not a hardware one. Hardware UIs are expensive and their power requirements are many orders of magnitude higher. BLE-based design can cut total product costs by more than half and increase usability by leveraging the customer’s smartphone. This provides a high-resolution screen, an already familiar user experience, and an Internet connection essentially for free.

The Mooshimeter displays a car startup transient.

The Mooshimeter displays a car startup transient. (Photo courtesy of Mooshim Engineering)

Wibree’s main technical value proposition is its extremely small power draw. Our company, Mooshim Engineering, offers the Mooshimeter, a wireless multimeter and data logger that uses your smartphone as a display. The transceiver we use for the Mooshimeter consumes a little less than 100 µW average draw to both send broadcast announcements every few seconds and listen for wake-up requests. This is roughly 10 to 100 times more power than a quartz watch, but 10 to 100 times less power than the watch’s backlight. Like the wristwatch, this draw is extremely peaky and depends heavily on usage. Products that only need to transmit can pull as little as 155 µJ per announcement. This provides more than a year of standby time.

Using 100-μW average draw as a starting point and assuming perfect power conversion, power could be provided by 2 to 4 mg per day of storage with a rechargeable lithium-ion battery; 1 to 3 g per day of storage with a supercapacitor; 10 mm2 of solar cells placed in a good spot outdoors; 5 cm2 of skin contact using thermal harvesters (e.g., a narrow but secure wristband); vibration harvesters, either on our limbs or in heavy industrial settings; or –10 dBm of wireless power transfer. An alkaline AA battery could ideally provide four years of service, although its self-discharge is more than 10% of the energy budget.

These power levels enable devices to have a high level of energy independence and become truly wireless—no data wire and no power wire. Thus architects can explore new relationships among devices, their environments, and their users. Connectors don’t compromise environmental seals, and frequent recharging doesn’t compromise the user’s experience.

The 100-μW  budget assumes the device just periodically announces its existence (as with wireless tethers and remote wake-up). But in uses that require more interesting payloads, the value proposition may be that the wireless link can fade into the noise of the energy budget. Remoting the user interface can also save energy, as even a dim indicator LED draws a milliwatt.

BLE is gaining its heaviest traction in electronic wearables, where users are likely to have BLE-enabled smartphones and a willingness to try new technologies. Fitness aids are enjoying early success because their sensor payloads are relatively low power and they address a large user base.

Medical wearables will take longer because of regulatory concerns and the user base. Diabetics may carry several screens with them, and often these devices will use proprietary radio protocols. Moving to a standard protocol could reduce the carry burden and provide a more secure data link. Standardization improves security through the principle of “given enough eyeballs, all bugs are shallow.”

Home appliances may be third-wave BLE adopters. The power draw is irrelevant here. A high-efficiency transformer wastes 10,000 times more power than the radio uses. It likely won’t eliminate the need for a hardware user interface either. Who wants to load an app to microwave their dinner? The convincing use case is to provide powerful diagnostic and monitoring capabilities. A refrigerator can tell a user’s phone when it needs a new filter. Washing machines can push notifications. Smoke detectors will proactively demand replacement batteries.

Until 2010, Wibree and its competitors offered incrementally improved energy independence. But BLE’s rapid market growth offers an inexpensive and unobtrusive way for system architects to provide new and compelling user experiences.

 

Eric VanWyk

Eric VanWyk

ABOUT THE AUTHOR
Eric VanWyk, who wrote this essay for Circuit Cellar, is co-founder of Mooshim Engineering and an adjunct instructor at Franklin W. Olin College of Engineering in Needham, MA, where he earned his BSc in Electrical and Computer Engineering in 2007. His background is in educational robotics, short-range wireless, and medical device development. Eric and his business partner, James Whong, have joined the rapidly growing number of innovators developing hardware and sensor add-ons that take advantage of Bluetooth Low Energy (BLE) 4.0 in today’s mobile devices. Their crowdfunded Mooshimeter is a multichannel circuit testing meter that uses a smartphone or tablet, via BLE, as a wireless, high-resolution graphical display.