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

ComponentType.MICROCONTROLLER
ComponentType.MICROCONTROLLER_ATMEL
ComponentType.MICROCONTROLLER_INFINEON
ComponentType.MICROCONTROLLER_ST
ComponentType.MCU_ATMEL

Similarity Weights (MCUSimilarityCalculator)

java

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

MCU Families

Family Groups

Group	Members
PIC	PIC16, PIC18, PIC24, PIC32
STM	STM8, STM32
ATM	ATMEGA, ATTINY, ATXMEGA
MSP	MSP430, MSP432

java

// Same family = 1.0 family similarity
calculator.calculateSimilarity("STM32F103", "STM32F407");
// High similarity (same STM32 family)

// Related family = 0.8 family similarity
calculator.calculateSimilarity("PIC16F877", "PIC18F4550");
// Good similarity (both PIC family)

Feature Codes

Code	Meaning
F	Flash memory
L	Low power
U	USB capable
W	Wireless
R	ROM version
T	Extended temperature

java

// Same feature codes contribute to similarity
calculator.calculateSimilarity("STM32F103", "STM32F407");
// 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

// Same series
calculator.calculateSimilarity("ATMEGA328", "ATMEGA328P");
// Very high similarity

// Close series
calculator.calculateSimilarity("ATMEGA328", "ATMEGA329");
// High similarity

// Far series
calculator.calculateSimilarity("ATMEGA328", "ATMEGA2560");
// Lower similarity

MicrocontrollerSimilarityCalculator Scoring

Condition	Score
Same manufacturer, same series, same package	1.0
Same manufacturer, same series, different package	0.9
Official replacement parts	0.8
Same series across manufacturers	0.7
Both microcontrollers, different series	0.5

Test Examples

MCUSimilarityCalculator

java

// Identical MCU
calculator.calculateSimilarity("ATMEGA328P", "ATMEGA328P");
// Returns 1.0

// Same family, different series
calculator.calculateSimilarity("STM32F103", "STM32F407");
// Returns > 0.5

// Different families
calculator.calculateSimilarity("STM32F103", "ATMEGA328");
// Returns lower similarity

MicrocontrollerSimilarityCalculator

java

// Same part, different package
calculator.calculateSimilarity("ATMEGA328P-AU", "ATMEGA328P-PU", registry);
// Returns >= 0.5

// Different MCUs
calculator.calculateSimilarity("ATMEGA328P", "STM32F103C8T6", registry);
// Returns 0.5 (base MCU similarity)

Common MCU Patterns

Atmel/Microchip AVR

code

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

STMicroelectronics STM32

code

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

Microchip PIC

code

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