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Next gen wireless apps with FRAM-based MCUs

Posted: 14 May 2012 ?? ?Print Version ?Bookmark and Share

Keywords:embedded wireless? ferroelectric random access memory? microcontroller?

More importantly, embedded FRAM opens up a new vector of flexibility when it comes to data memory organization. Data-logging procedures can become more adaptive and adjust their buffer size. Endurance of 1015 (1 thousand trillion) access cycles (both writes and reads) offers a preferred solution for data storing and logging purposes.

Enhancing wireless networks
The motivation for many wireless applications is to cut the cord, minimize the number of components and reduce the installation cost. Unfortunately, the inaccessibility issue that wireless systems try to solve remains a problem if maintenance is required. While the battery significantly contributes to the overall bill of the solution, the maintenance cost could actually outweigh the cost of the batteries by four times. Part of this cost is because of the unreliability nature of wireless and battery-powered systems. Improving battery life and data reliability will also solve many maintenance problems.

Reliability with zero-power write ensures data integrity even in systems susceptible to abrupt power loss. A zero-power write means sufficient energy is always stored to guarantee the completion of the current FRAM write, even in the event of sudden power failure. This feature significantly improves the integrity of the data or memory being processed or captured.

The high-speed and low-power write equates to low average current as well as shorter duration for such current consumption. Both of these aspects help shrink the data-logging energy signature, minimizing the total energy consumed per data-logging event. This results in improved battery life time, or reduces the capacity requirement for the energy storage in the system. Additionally, peak current is a key design consideration for energy harvesting applications where the type of energy storage places a restriction on peak current. Unlike a Flash write that requires a charge pump and high peak currents, a FRAM low-power write allows for preservation of high-peak events only for radio operations. This further alleviates the stringent requirements in power supply for energy harvesting systems.

Wireless security, IP protection
The open- nature of wireless communication inherently makes it vulnerable to security threats. Security is critical in wireless systems to protect both over-the-air transmission data and intellectual property (IP) encapsulated in the wireless nodes. FRAM high-endurance memory allows for abundant storage for encrypted data, security keys and on-the-fly key generation. The same memory can also be used as processing buffer space for any encryption or security algorithm.

For instance, some of the NFC or secure credit card transaction applications require key generations and memory writes up to 100 times a day. On a typical Flash memory with 10K write/erase cycle, achieving 100K write/erase cycle endurance requires 10B of memory for every one byte of data. In comparison, a FRAM memory byte can endure 1015 write/erase cycles C 100 billion times more than a Flash byte. For applications that require high endurance in the order of millions of write/erase cycles, FRAM's endurance specification is unmatched by other embedded non-volatile memory technologies available today.

The IP protection mechanism can also be enhanced thanks to the duality of FRAM memory. Specifically, IP vendors can easily block off a contiguous segment in FRAM to secure both their IP code as well as the data memory needed to process during execution. This allows for IP vendors to conveniently package up their IP and ensures higher level of protection even against taint tracking.

Conclusion
On the road to ubiquity and reaching out to improve every aspect of human lives, wireless applications have seen many challenges and successes. The countless number of advancements in microcontrollers, radios and embedded systems have been instrumental to enable such incremental improvements. Perhaps this revolutionary universal memory can serve as a necessary nudge for wireless systems to gain the momentum necessary to break through and become truly universal.

About the author
Dung Dang is an applications engineer for Texas Instruments' ultra-low-power MSP430 microcontroller (MCU) group. He joined Texas Instruments in 2007 and has since served in various roles in new product development.

Mr. Dang works closely with MSP430 MCU silicon development in addition to supporting development tools and software solutions. His focus also includes realizing various ultra-low-power wireless solutions on MSP430 MCUs. Dung Dang holds an MSEE degree from St. Mary's University at San Antonio, concentrating on embedded systems and image processing.

To download the PDF version of this article, click here.


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