Determining Dynamic Memory Latency Impact on Low Power Mesh Re Keying Operations
Dynamic memory access delays during mesh key rotation increase microcontroller active time, causing battery voltage droop and lost frame acknowledgments.
Flash Write Latency
Meaning
Time delay required to commit a page of data to non-volatile solid-state storage dictates the maximum logging rate of sensor devices. High flash write latency can cause incoming data queues to overflow if the processor receives information faster than it can write. This metric is a critical factor when designing high-frequency telemetry systems.
Program Delay
Writing to flash memory involves a charge pump that generates high voltages to alter the floating-gate transistors. This physical process explains why the flash write latency is orders of magnitude longer than the read latency. During this write cycle, the memory bus is often locked, halting other read operations.
Wear Assessment
As the memory cells undergo repeated write and erase cycles, the oxide layer degrades and slows the programming operation. This degradation causes the flash write latency to increase gradually as the device reaches its write-endurance limit. Monitoring this delay provides a direct way to predict flash memory failure before data loss occurs, ensuring that preventative maintenance can be scheduled.
Firmware can automatically flag sectors that exceed a defined latency threshold to isolate them.
Buffer Strategy
Developers use RAM buffers to cache incoming sensor data while the flash memory executes the write command. This architecture minimizes the impact of the flash write latency on the responsiveness of the system. In addition, writing larger blocks of data at once reduces the overall frequency of these write delays.