MCU Similarity Calculator Skill

Guidance for working with MCU similarity calculators 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

There are two MCU-related calculators:

MCUSimilarityCalculator (Simple Interface)

• Implements SimilarityCalculator
• Uses pattern matching for family/series/features
• No PatternRegistry required

MicrocontrollerSimilarityCalculator (Component Interface)

• Implements ComponentSimilarityCalculator
• Uses manufacturer handlers for extraction
• Requires PatternRegistry

Applicable Types (MicrocontrollerSimilarityCalculator)

java
1ComponentType.MICROCONTROLLER
2ComponentType.MICROCONTROLLER_ATMEL
3ComponentType.MICROCONTROLLER_INFINEON
4ComponentType.MICROCONTROLLER_ST
5ComponentType.MCU_ATMEL

Similarity Weights (MCUSimilarityCalculator)

java
1familySimilarity * 0.5   // Family is most important
2seriesSimilarity * 0.3   // Series number
3featureSimilarity * 0.2  // Feature codes (F, L, U, etc.)

MCU Families

Family Groups

java
1// Same family = 1.0 family similarity
2calculator.calculateSimilarity("STM32F103", "STM32F407");
3// High similarity (same STM32 family)
4
5// Related family = 0.8 family similarity
6calculator.calculateSimilarity("PIC16F877", "PIC18F4550");
7// Good similarity (both PIC family)

Feature Codes

java
1// Same feature codes contribute to similarity
2calculator.calculateSimilarity("STM32F103", "STM32F407");
3// Both have F (Flash) feature

Series Similarity

Series numbers are compared numerically:

• Same series = 1.0
• Close numbers (within 100) = partial similarity
• Far numbers = lower similarity

java
1// Same series
2calculator.calculateSimilarity("ATMEGA328", "ATMEGA328P");
3// Very high similarity
4
5// Close series
6calculator.calculateSimilarity("ATMEGA328", "ATMEGA329");
7// High similarity
8
9// Far series
10calculator.calculateSimilarity("ATMEGA328", "ATMEGA2560");
11// Lower similarity

MicrocontrollerSimilarityCalculator Scoring

Test Examples

MCUSimilarityCalculator

java
1// Identical MCU
2calculator.calculateSimilarity("ATMEGA328P", "ATMEGA328P");
3// Returns 1.0
4
5// Same family, different series
6calculator.calculateSimilarity("STM32F103", "STM32F407");
7// Returns > 0.5
8
9// Different families
10calculator.calculateSimilarity("STM32F103", "ATMEGA328");
11// Returns lower similarity

MicrocontrollerSimilarityCalculator

java
1// Same part, different package
2calculator.calculateSimilarity("ATMEGA328P-AU", "ATMEGA328P-PU", registry);
3// Returns >= 0.5
4
5// Different MCUs
6calculator.calculateSimilarity("ATMEGA328P", "STM32F103C8T6", registry);
7// Returns 0.5 (base MCU similarity)

Common MCU Patterns

Atmel/Microchip AVR

ATMEGA 328 P -AU
│      │   │  │
│      │   │  └── Package (AU=TQFP)
│      │   └───── Variant (P=Picopower)
│      └───────── Series number
└──────────────── Family

STMicroelectronics STM32

STM32 F 103 C8 T6
│     │ │   │  │
│     │ │   │  └── Package (T6=LQFP48)
│     │ │   └───── Memory/pins
│     │ └───────── Series
│     └─────────── Type (F=Foundation)
└───────────────── Family

Microchip PIC

PIC16 F 877 A
│     │ │   │
│     │ │   └── Variant
│     │ └────── Series
│     └──────── Memory type (F=Flash)
└────────────── Family

Learnings & Quirks

Family Detection

• Regex ^([A-Z]+)\d+ extracts family prefix
• Empty family = 0.0 family similarity

Series Number Extraction

• Extracts first numeric sequence
• Compared as integers for proximity

Feature Code Position

• Usually at end of part number
• Regex [A-Z]+$ extracts trailing letters

Package Codes

• Vary significantly by manufacturer
• Don't affect core part equivalence
• Same MCU in different package = HIGH similarity

Cross-Family Comparison

• Different families get Levenshtein similarity
• Never returns > 0.8 for different families