Use when working with memory IC similarity calculations - comparing EEPROM/Flash MPNs, understanding I2C/SPI interface matching, equivalent groups across manufacturers, or memory-specific similarity logic.
Guidance for working with MemorySimilarityCalculator in the lib-electronic-components library.
For metadata-driven similarity architecture, see /similarity-metadata:
The MemorySimilarityCalculator compares memory ICs based on:
ComponentType.MEMORY
// Any type starting with "MEMORY_"
// Returns true for null to handle unrecognized memory devices
HIGH_SIMILARITY = 0.9; // Equivalent parts
MEDIUM_SIMILARITY = 0.7; // Same type/interface, close specs
LOW_SIMILARITY = 0.3; // Different capacity or interface
| Capacity | Equivalent Parts |
|---|---|
| 256Kbit | 24LC256, AT24C256, M24C256, CAT24C256 |
| 512Kbit | 24LC512, AT24C512, M24C512, CAT24C512 |
| 1Mbit | 24LC1024, AT24C1024, M24C1024 |
calculator.calculateSimilarity("24LC256", "AT24C256", registry);
// Returns >= 0.7 (equivalent I2C EEPROMs)
| Capacity | Equivalent Parts |
|---|---|
| 256Kbit | 25LC256, 25AA256, AT25256, M95256 |
| 512Kbit | 25LC512, 25AA512, AT25512, M95512 |
| Capacity | Equivalent Parts |
|---|---|
| 32Mbit | W25Q32JV, W25Q32FW, MX25L3233F, S25FL032P, IS25LP032 |
| 64Mbit | W25Q64JV, W25Q64FW, MX25L6433F, S25FL064P, IS25LP064 |
| 128Mbit | W25Q128JV, W25Q128FW, MX25L12833F, S25FL128, IS25LP128 |
calculator.calculateSimilarity("W25Q32JV", "MX25L3233F", registry);
// Returns >= 0.3 (same capacity SPI Flash)
I2C and SPI memory have lower similarity due to different interfaces:
calculator.calculateSimilarity("24LC256", "25LC256", registry);
// Returns <= 0.7 (same capacity, different interface)
Different capacities return LOW_SIMILARITY:
calculator.calculateSimilarity("W25Q32JV", "W25Q128JV", registry);
// Returns 0.3 (same family, different size)
Package codes don't significantly affect similarity for memory:
| Prefix | Manufacturer | Type |
|---|---|---|
| 24LC | Microchip | I2C EEPROM |
| AT24C | Atmel/Microchip | I2C EEPROM |
| M24C | ST | I2C EEPROM |
| CAT24C | ON Semi | I2C EEPROM |
| 25LC/25AA | Microchip | SPI EEPROM |
| AT25 | Atmel/Microchip | SPI EEPROM |
| M95 | ST | SPI EEPROM |
| W25Q | Winbond | SPI Flash |
| MX25L | Macronix | SPI Flash |
| S25FL | Spansion/Cypress | SPI Flash |
| IS25LP | ISSI | SPI Flash |
// Same I2C EEPROM
calculator.calculateSimilarity("24LC256", "24LC256", registry);
// Returns 1.0
// Cross-manufacturer I2C EEPROM
calculator.calculateSimilarity("24LC256", "AT24C256", registry);
// Returns >= 0.7
// Same Flash, different manufacturer
calculator.calculateSimilarity("W25Q64JV", "MX25L6433F", registry);
// Returns >= 0.3
// Different capacity
calculator.calculateSimilarity("24LC256", "24LC512", registry);
// Returns 0.3
Status: ✅ Converted (PR #117)
The MemorySimilarityCalculator now uses a metadata-driven approach with spec-based comparison.
| Spec | Importance | Tolerance Rule | Description |
|---|---|---|---|
| memoryType | CRITICAL | exactMatch | EEPROM, Flash, SRAM, etc. |
| capacity | CRITICAL | exactMatch | 256Kbit, 512Kbit, 1Mbit, etc. |
| interface | HIGH | exactMatch | I2C, SPI, Parallel |
| package | LOW | exactMatch | SOIC, DIP, TSSOP, etc. |
// Short-circuit check for CRITICAL incompatibility
if (!memoryType1.isEmpty() && !memoryType2.isEmpty() && !memoryType1.equals(memoryType2)) {
return LOW_SIMILARITY;
}
if (!capacity1.isEmpty() && !capacity2.isEmpty() && !capacity1.equals(capacity2)) {
return LOW_SIMILARITY;
}
// Weighted spec scoring
// memoryType: CRITICAL (1.0 weight)
// capacity: CRITICAL (1.0 weight)
// interface: HIGH (0.7 weight)
// package: LOW (0.2 weight)
| Comparison | Legacy Result | Metadata Result | Notes |
|---|---|---|---|
| 24LC256 vs 24LC256 | 1.0 | 1.0 | Identical |
| 24LC256 vs AT24C256 | 0.7+ | 0.85 | Equivalent I2C EEPROM |
| W25Q32JV vs MX25L3233F | 0.3+ | 0.61 | Same capacity Flash |
| 24LC256 vs 24LC512 | 0.3 | 0.3 | Short-circuit on capacity |
| W25Q32JVSSIQ vs W25Q32JVSFIQ | 0.7+ | 0.93 | Same Flash, different package |
Why more accurate: Metadata approach prioritizes capacity and type matching, with interface as secondary concern.
24xx = I2C interface, 25xx = SPI interfaceC often indicates CMOSJV, FW, JW on Winbond = package/voltage variantsA, B, C suffixes = revisions (usually compatible)