Newnan, GA (PRWEB) August 14, 2006
When AOL created its AOL Wireless division recently, the goal was extending interactive services to mobile devices, simplifying, and promoting their usage. To further this end, Paul R. Nash AOL Wireless’ Chief Architect, who oversees hardware and software design for cell phones and other wireless devices, proactively searched for a way to expedite the design cycle while minimizing any inadvertent engineering bugs.
The Cost of Flawed Design
“We build software for devices that have to run all day, every day,” says Nash. “People get really upset if their phone crashes, their wireless device won’t access the network, or their battery dies. Getting stability and power consumption as perfect as possible is critically important.”
“On top of this, the challenge is to satisfy market demand for new portable devices better, faster, and cheaper in ever shorter design cycles,” adds Nash. “At stake is hitting national product launch dates that could involve millions of dollars in marketing, cross promotion, inventory, and opportunity costs.”
According to Nash, it’s common for engineers in the industry to rush to meet cost and launch dates, only to sacrifice stability or battery life. Though executives immediately notice when product is late or over budget, customer grumblings or a higher return rate may escape notice until much later. By then engineers are often working on the next iteration, and original design flaws remain.
“If the same flawed base design is used across multiple product lines, the cost of product instability and short battery life rises,” says Nash. “Because you’re usually stuck with design flaws for a while and want to minimize support or potential recall costs, you’ve got to get design right from the start. That requires powerful, proactive engineering tools.”
Previously, the company had used a simple four-channel digital oscilloscope to verify and troubleshoot voltage and time elements of component design. But the oscilloscope had significant drawbacks.
“If we zoomed out enough to capture a good slice of time on the protocol, when we zoomed in we wouldn’t have enough data points to distinguish the wave forms or decode bits,” says Nash. “The triggering wasn’t quite right, the bandwidth not sufficient. We were left wondering, ‘Does the signal really look like this, or is the probe distorting it?’ Trying to look at high speed signals with it was like working with cement gloves on.”
Furthermore, the GPIB standard they used to connect their oscilloscope and multimeter provided only limited data and communication speed, while requiring expensive PC card adapters.
Stopping Bugs Before They Hatch
To meet AOL Wireless’ expedited design and quality goals, more powerful engineering tools were needed. After thorough research, Nash turned to a SignalExplorer digital oscilloscope from Yokogawa, a leading manufacturer of process, test, and measurement instruments, headquartered near Atlanta, Georgia. For a test trial, he borrowed a digital oscilloscope capable of waveform, logic and protocol analysis of serial data bus types such as I2C and SPI, along with advanced zoom, triggering, and other functions. When Nash put the digital oscilloscope to the test, the payoff was immediate.
AOL Wireless had an auxiliary micro-controller that communicated to a main processor via I2C. Nash was developing firmware for the micro-controller, but the device was going to sleep in the middle of an I2C transaction and hanging the bus. “I’d normally have put a bunch of debugging in my code and tried to figure out where it was hanging the bus,” says Nash. “Trying to capture something on the old oscilloscope and guess at what’s going on would’ve taken me at least two days to track the problem down.”
“With the Yokogawa digital oscilloscope however, I was able to put probes on the bus, run my test case and, instantly got an analysis of all the bytes that had been sent, received, and where the bus had stopped in a particular state,” says Nash. “I spotted the problem, went into the firmware, made one change and it worked perfectly. Including set up, it took just 20 minutes to resolve the I2C transaction problem. Most importantly, I was certain I fixed the actual problem rather than just masking it. Because the digital oscilloscope gave me a perfect view of what was really happening I didn’t have to guess at all.”
Having saved two days of development time and cost on the single test case while improving stability and power conservation, Nash purchased the digital oscilloscope for AOL Wireless. The company uses the oscilloscope to proactively debug general and custom serial data buses including I2C and SPI, as well as parallel data buses, memory and hard drive formats.
“The digital oscilloscope gives us the flexibility to meet whatever bus design is required,” says Nash. “Along with deep memory, logic and protocol analysis, we can scale to capture the signal with as many repetitions or at whatever resolution needed. Combined with advanced triggering and search capabilities, the oscilloscope lets us hone development quickly and cost effectively.”
Since the digital oscilloscope can save information via Ethernet to an FTP server and connect to USB peripherals as needed, it’s fully accessible over a network. The oscilloscope’s automatic bus analysis capability along with its ability to independently run long-term tests and email the results have saved AOL Wireless significant development resources.
“Instead of having to squint and move cursors to figure out the 1s and 0s, the digital oscilloscope provides automatic bus analysis,” says Nash. “This saves us a lot of time and effort and is particularly important for I2C and SPI bus analysis. Its ability to set up out of bound criteria is also helpful, especially when running long-term tests for infrequent events like incoming calls or low signal conditions. Because you can set up a test and have it email you the results, it essentially baby-sits your experiment while you move on to other things.”
Recently, Nash has used the digital oscilloscope to trigger a sequence of about 50 short commands over a serial bus for a complicated new device. The oscilloscope triggers at the beginning of each of the serial transactions. Not only does it provide a picture of each serial transaction, but also it enables capturing all 50 transactions together and scrolling through them one-by-one later.
“With our old oscilloscope, the triggers came too fast; we couldn’t stop at a specific trigger; and we couldn’t capture multiple events at the same time due to insufficient memory,” says Nash.
“Instead of buying an expensive, dedicated logic analyzer to look at the whole serial protocol we’re using the Yokogawa oscilloscope,” says Nash. “With it we verified the correct command sequence down to the bit forms within minutes, and confirmed we were programming the peripheral and processor to send the right waveforms.”
On another occasion, AOL Wireless had to debug a synchronous digital video signal interface between an LCD and CPU controller. They had to monitor 16 signals including data lines, a clock line, two synch lines, and a control bus; and it was critical to confirm whether data was sent from the CPU in the right format. The process was complicated because the digital video protocol is complex and flexible, meaning that every LCD or other peripheral can have unique timing needs.
“If we wanted to look at the pixel clock or other signals with our old oscilloscope, we would’ve had to change our bench set up and look at the data in separate groups,” says Nash. “But not being able to look at the signals in real-time is like feeling your way in the dark. If you turn on the LCD and it doesn’t run, which side is misconfigured? You don’t know.”
Instead, Nash used the Yokogawa digital oscilloscope to watch and name all 16 signals on screen at the same time. Ample memory allowed capturing a whole frame of data and cursoring around to zoom in on specific parts in question.
“Using the digital oscilloscope we watched an entire frame of video on screen at once and zoomed in on a particular line of video or pixel data as needed,” explains Nash. “It integrated the process and was like looking at the forest and the trees. It confirmed the control chip was set up correctly, and helped us figure out all the details of the LCD interface a week earlier than we otherwise would have.”
Another time Nash used the digital oscilloscope to debug a memory bus. He had to determine what the drivers were doing and whether there were any termination issues. With the oscilloscope, he determined there were memory corrections and that some vendor documentation was inaccurate. “We wrote to a memory address, read back the values, and the values were different,” says Nash. “The oscilloscope showed the truth of the situation regardless of what the documents said. With accurate data, we quickly found a solution.”
“On a typical product cycle of about a year, the Yokogawa oscilloscope could save us weeks, even months of development time,” concludes Nash. “It can make the difference between hitting a critical launch date like Christmas or missing it. Not only that, but I can’t count the number of bugs I’ve avoided. It has helped to rein in cost, increase stability, and improve battery life — all pluses for us and the end customer.”
For more information on optimally testing, viewing, and analyzing electrical signals for system design and development, contact:
Yokogawa Corporation of America
2 Dart Road, Newnan, GA, 30265
Phone: (770) 253-7000
Fax: (770) 251-2088
Or visit their Web site at: http://www.yokogawa.com/tm.
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