Connected battery-based devices require always more computing power to run feature rich application programs while using the minimal energy to ensure the longest usage without recharge. As a result, fabless companies need to hunt down every "mA" to satisfy the low-power expectations of their SoC users.
Numerous System-on-Chips rely on a Non-Volatile flash Memory – either embedded or external – to store the application program as it provides an easy firmware update whenever needed. A quick analysis shows that each access to the flash memory requires a significant amount of energy, thus providing room for appealing savings. At the same time, the main challenge for SoC designers is that application program characteristics are unknown in most cases at the date of SoC design-in, making any performance optimization challenging.
R-Stratus-LP is the first cache controller silicon IP optimized to address these low-power challenges. It indeed relies on an innovative architecture which reduces drastically the number of flash accesses, by up to 1,000 times, whatever the targeted CPU frequency, while enabling on-the-fly reconfiguration of relevant cache parameters for specific application program characteristics so as to achieve ultimate power savings.
Benchmarking shows that an embedded flash memory subsystem relying on R-Stratus-LP consumes up to 3x less power than a flash memory connected to an MCU with a prefetch system. Such power savings are even more impressive with external flash memories as R-Stratus-LP allows running code directly from a flash memory (Execute-In-Place, XIP). Comparisons with other cache controllers also demonstrate that power consumption may be minimized thanks to R-Stratus-LP while using a cache memory of much lower capacity, thus enabling both area and power consumption savings for the same data throughput.
As selection of the appropriate values for cache parameters may be a burden for SoC designers, this innovative cache controller IP is provided with an EDA solution which allows easily identifying the best cache controller settings.