Overall Context:

These excerpts are from datasheets for GD25LE series flash memory devices (GD25LE10, GD25LE20, etc.). They detail the device's protected area functionality. Essentially, the datasheet is describing how you can selectively protect parts of the flash memory from being modified.

1. GD25LE40C (Most Extensive Tables)

️· Protected Area Concept: The `CMP` (Compare) bit in the status register controls the behavior of the protection system. `CMP=0` and `CMP=1` have different protection tables.
️· Protection Table (CMP=0):
- This table defines the protected blocks based on the settings of BP4, BP3, BP2, BP1, and BP0 bits in the status register.
- It maps these bit configurations to a range of memory blocks and addresses.
- The `Density` column indicates the size of a "block" (e.g., 4KB, 8KB, 16KB, 32KB).
- The `Portion` column expresses the ratio of the protected region compared to the total memory (e.g., Upper 1/8 means 1/8 of the total memory is protected).
️· Protection Table (CMP=1):
- Provides an alternate set of protected regions, determined by the status register bits.
️· How it works:
- When writing to a memory address, the device checks if the address falls within a protected block.
- If the address is within a protected block, a write attempt will be rejected (a status flag indicates failure). If it's outside of a protected block, the write operation will be successful.
️· Key Columns in Protection Tables:
- `BPx` bits: Status Register bits used to define the protection.
- `Blocks`: Number of blocks protected.
- `Addresses`: Starting address of the protected memory region.
- `Density`: Size of each memory block.
- `Portion`: Proportion of the memory that is protected.

2. GD25LE20C (Simplified Table)

️· Similar protection concept using BPx bits, but with fewer protection options compared to the GD25LE40C.
️· The protection is determined by BP4, BP3, BP2, BP1 and BP0 in status register
️· Simplified table with fewer protection options compared to the GD25LE40C.

General Notes:

️· Status Register: The behavior of the protection system is controlled by writing specific values to the status register. This is a core part of how you configure the protection.
️· Configuration: To implement the protection, you must carefully configure the status register to define the desired protected areas.
️· Applications: This feature is useful for protecting critical firmware, boot sectors, or configuration data from accidental or malicious modification.