Working within tight limits.
WHAT MEMORY EXISTS
Program storage, holding firmware Volatile working memory, usually very small Persistent storage for configuration and buffers
WHAT CONSUMES WORKING MEMORY
Buffers for radio and sensors The stack Static variables
WHAT STACK OVERFLOW CAUSES
Corruption that appears as unrelated faults.
WHAT DETECTS IT
Filling the stack with a pattern and checking how much was used.
WHAT TO MEASURE
Peak usage, under worst-case conditions.
WHAT WORST CASE MEANS
Deepest call path, largest message, error handling active.
WHAT PERSISTENT STORAGE HAS
Limited write cycles.
WHY THAT MATTERS
Writing frequently wears it out within the device's intended life.
WHAT TO DO
Write rarely Distribute writes across the storage Buffer in memory and commit periodically
WHAT TO BE CAREFUL WITH
Power loss during a write, which corrupts.
WHAT PREVENTS THAT
Writing to an alternate location and switching, with a validity marker.
WHAT TO MONITOR IN THE FIELD
Free memory, reported periodically.
WHAT A DECLINING TREND INDICATES
A leak, which will eventually cause failure.
WHAT TO TEST
Behaviour when memory is exhausted, deliberately.
