31.1.14.2 BFM and PFM Swap Organization Notes

Single Panel Device Organization Notes

When a device contains a single panel flash system, swapping changes how logical system addresses are mapped to physical flash addresses within the single panel. When not swapped, the Lower region maps to the lower half of the physical flash addresses and the Upper region maps to the upper half of the physical flash addresses. When swapped, the Lower region maps to the upper half of the physical flash addresses and the Upper region maps to the lower half of the physical flash addresses.

Dual Panel Device Organization Notes

When the devices contains a Dual Panel flash system, swapping changes the panel in which the Upper and Lower regions exists. The natural order, not swapped, is for the Lower region to be mapped to the lower numbered panel and the Upper region to be mapped to the higher numbered panel. When swapped, the Lower region is mapped to the higher number panel and the Upper region is mapped to the lowered number panel.

Since a dual panel system supports Live Update (aka Read While Write - RWW) for access to different panels, swapping BFM when not swapping PFM can impact code execution if using writes and erase NVMOP operations during mission mode execution.

BFM Swap Protection

It may be desirable to prevent swapping BFM after setup. The BFSLOCK allows BFSWAP (and itself) to be write locked preventing them from changing. Lock is in effect until the next reset.

PFM Swap Protection

It may be desirable to prevent swapping PFM after setup. The PFSLOCK allows PFSWAP (and itself) to be write locked preventing them from changing. Lock is in effect until the next reset.