1. General Information - GD25LH Series (Likely GD25LH40C, GD25LH20C, GD25LH10C)
️· What they are: These are Flash memory devices. Flash memory is a type of non-volatile memory – it retains data even when power is removed.
️· Likely Denominations: The text refers to GD25LH40C, GD25LH20C, and GD25LH10C. The '40C' likely refers to a 4Mb (4096kb) density, '20C' to 2Mb (2048kb), and '10C' to 1Mb(1024kb).
️· Uniform Sector: The term "uniform sector" implies a standard size block of memory being written and erased, simplifying the memory management.
2. Protected Area Size Tables (CMP=0 and CMP=1)
️· What they do: These tables define how memory blocks can be protected from writing. This is a security feature to prevent accidental or malicious modification of critical data.
️· `CMP` Register: The tables are presented for two different CMP register values, 0 and 1. This register likely controls some aspect of the memory protection mechanism.
️· `BP4`, `BP3`, `BP2`, `BP1`, `BP0`: These are bits within a register (likely a status or configuration register). The combination of these bits determines which memory blocks are protected.
️· `Blocks`: Indicates the number of blocks protected.
️· `Addresses`: Lists the starting memory address of the protected area. This is expressed in hexadecimal format (e.g., `000000H` is memory address 0).
️· `Density`: Refers to the total memory capacity (e.g., 64KB, 128KB, 256KB).
️· `Portion`: Describes the fraction of memory that is protected based on the register settings (e.g., Upper 1/2, Lower 1/8).
️· The Tables are Complex: Interpreting these tables requires understanding the register map and how the bits interact. There are several combinations, each defining different protected areas.
Specific Table Differences:
️· GD25LH40C (CMP=0 and CMP=1): Offers the most granular protection options, with various block sizes and addresses. The CMP=1 table has fewer protection options.
️· GD25LH20C (CMP=0 and CMP=1): Offers fewer protection options than the 40C.
️· GD25LH10C: No tables are provided for this, so its protected area functionality might be simpler or require a different mechanism.
Key Takeaways & What You'll Need to Understand This Fully:
️· Register Map: You're missing the crucial register map that explains what each bit in the status register means.
️· Memory Organization: You need to know how memory is organized into blocks and sectors to understand the addresses and portions.
️· CMP Register: The specific function of the CMP register needs to be known. It's the key to understanding the impact of CMP=0 vs CMP=1.
To use these tables effectively, you would need to:
1. Identify the target device: Determine which specific GD25LH model you are working with (e.g., GD25LH40C, GD25LH20C, GD25LH10C).
2. Consult the full datasheet: Refer to the complete datasheet for the device to understand the register map, memory organization, and how to configure the protected areas.
3. Experiment: Test different register configurations to verify the protected areas and ensure they work as expected.