NAND Flash wear leveling is an established error- and fault-management technique in SSDs, but Texas Instruments is touting on-chip Flash and EEPROM durability in a low-cost microcontroller: the TI Stellaris M4F series based on the ARM Cortex-M4F microprocessor core. There’s a 256Kbyte Flash memory on the TI Stellaris M4F microcontroller. Here are the relevant words TI uses to describe the Flash memory on the device:
“It can be hard to get excited about memory. It is often simply taken for granted. But changing to a TI 65nm process for the Stellaris LM4F family raises the products to a new level of reliability and integration. Borrowing the Flash technology that TI developed for use in automotive products, the Stellaris LM4F MCUs have extended memory durability by an order of magnitude beyond competition. The minimum number of times the flash memory on these MCUs can be erased and reprogrammed is as high as 100,000 cycles.
For most applications, this breakthrough eliminates any concern of wearing out the memory from re-flashing for data collection, configuration parameters or program modifications. More of the high-reliability Flash is also available for customer-written code because StellarisWare drivers are embedded in a small mask ROM on-chip.
All Stellaris LM4F MCUs have the StellarisWare binaries committed in on-chip ROM, including the peripheral drivers, the in-system programming routines, utilities such as CRC (cyclic redundancy check) algorithms, and AES (advanced encryption standard) tables. These APIs (application programming interfaces) let the programmer take full advantage of these well-proven services, routines and tables, while leaving all of the flash for customer and application-specific code.”
There’s also a 2Kbyte EEPROM on the TI Stellaris microcontroller, described like this:
“There are many other memory features on the MCUs, but one new memory type deserves special attention. The new Stellaris LM4F MCUs have 2K bytes of secure, on-chip EEPROM. EEPROM is normally used to store long-term variables that may even need to survive power outages and dead batteries. Since the implementation is interrupt-enabled, the integrated memory allows for the execution of code while writing values to nonvolatile memory (execute-while-write). The EEPROM use is architected using a built-in wear- leveling technique that ensures each location can be modified 500,000 times. If the data was re-written 100 times a day, the EEPROM would last nearly 15 years!”
Make no mistake. Memory is a very competitive part of any SoC or system design, no more and no less important that other components. Memory is not as simple as it might seem at first and the right approach to providing memory in a design can make a big difference in its perceived value.
For more information on the TI Stellaris M4F microcontroller and its new eval board, see “TI Stellaris LaunchPad eval board features ARM Cortex-M4F. Intro price: $4.99. Get yours now.”