Cantara/similarity-memory
.claude/skills/similarity-memory/SKILL.md
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.
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skillsauthnpx skillsauth add Cantara/lib-electronic-components similarity-memoryInstall this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.
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SKILL.md
- name:
- similarity-memory
- description:
- 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.
Memory Similarity Calculator Skill
Guidance for working with MemorySimilarityCalculator in the lib-electronic-components library.
For metadata-driven similarity architecture, see /similarity-metadata:
- SpecImportance levels (CRITICAL, HIGH, MEDIUM, LOW, OPTIONAL)
- ToleranceRule types (exactMatch, percentageTolerance, minimumRequired, etc.)
- SimilarityProfile contexts (DESIGN_PHASE, REPLACEMENT, COST_OPTIMIZATION, etc.)
- Calculator integration patterns and gotchas
Overview
The MemorySimilarityCalculator compares memory ICs based on:
- Equivalent groups - Cross-manufacturer equivalents
- Memory type - EEPROM, Flash, etc.
- Interface - I2C, SPI
- Capacity - Must match for high similarity
- Voltage range - Operating voltage compatibility
Applicable Types
ComponentType.MEMORY
// Any type starting with "MEMORY_"
// Returns true for null to handle unrecognized memory devices
Similarity Thresholds
HIGH_SIMILARITY = 0.9; // Equivalent parts
MEDIUM_SIMILARITY = 0.7; // Same type/interface, close specs
LOW_SIMILARITY = 0.3; // Different capacity or interface
I2C EEPROM Equivalents
| 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)
SPI EEPROM Equivalents
| Capacity | Equivalent Parts | |----------|------------------| | 256Kbit | 25LC256, 25AA256, AT25256, M95256 | | 512Kbit | 25LC512, 25AA512, AT25512, M95512 |
SPI Flash Equivalents
| 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)
Interface Rules
I2C and SPI memory have lower similarity due to different interfaces:
calculator.calculateSimilarity("24LC256", "25LC256", registry);
// Returns <= 0.7 (same capacity, different interface)
Capacity Rules
Different capacities return LOW_SIMILARITY:
calculator.calculateSimilarity("W25Q32JV", "W25Q128JV", registry);
// Returns 0.3 (same family, different size)
Package Handling
Package codes don't significantly affect similarity for memory:
- Same memory, different package = HIGH_SIMILARITY (0.9)
- Same memory, compatible package = HIGH_SIMILARITY (0.9)
- Same memory, different package type = ~0.8
Manufacturer Prefixes
| 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 |
Test Examples
// 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
Metadata-Driven Implementation (January 2026)
Status: ✅ Converted (PR #117)
The MemorySimilarityCalculator now uses a metadata-driven approach with spec-based comparison.
Specs Compared
| 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. |
Implementation Pattern
// 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)
Behavior Changes
| 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.
Learnings & Quirks
Part Number Patterns
24xx= I2C interface,25xx= SPI interfaceCoften indicates CMOS- Capacity in Kbits: 256 = 32KB, 512 = 64KB, 1024 = 128KB
Revision Suffixes
JV,FW,JWon Winbond = package/voltage variantsA,B,Csuffixes = revisions (usually compatible)
Voltage Compatibility
- Standard: 2.7V-5.5V
- Low voltage: 1.7V-3.6V (check compatibility)
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