This directory contains standardized bus configurations (I2C, SPI, UART, BLE) that component tests use, enabling multiple components to be tested together in Phase 2.

Purpose

These common configs allow multiple components to share a single bus, dramatically reducing CI time from ~12 hours to ~2-3 hours by compiling multiple compatible components together.

Structure

common/
├── i2c/
│   ├── esp32-idf.yaml
│   ├── esp32-ard.yaml
│   ├── esp32-c3-idf.yaml
│   ├── esp32-c3-ard.yaml
│   ├── esp8266-ard.yaml
│   └── rp2040-ard.yaml
├── spi/
│   └── esp32-idf.yaml
├── uart/
│   └── esp32-idf.yaml
└── ble/
    ├── esp32-idf.yaml
    ├── esp32-ard.yaml
    └── esp32-c3-idf.yaml

How It Works

Current State (Phase 1)

Each component test includes the common bus config:

# tests/components/bh1750/test.esp32-idf.yaml
packages:
  i2c: !include ../../test_build_components/common/i2c/esp32-idf.yaml

<<: !include common.yaml

The common config provides:

Standardized pin assignments
A shared bus instance (i2c_bus, spi_bus, etc.)

The component's common.yaml just defines the sensor:

# tests/components/bh1750/common.yaml
sensor:
  - platform: bh1750
    name: Living Room Brightness
    address: 0x23

The component auto-detects the shared bus - no need to specify i2c_id.

Future State (Phase 2)

Create merged test YAMLs combining multiple compatible components:

# tests/merged_components/i2c_sensors_group_1.esp32-idf.yaml
esphome:
  name: test_i2c_group_1

esp32:
  board: nodemcu-32s
  framework:
    type: esp-idf

packages:
  # Shared I2C bus
  i2c: !include ../test_build_components/common/i2c/esp32-idf.yaml

  # Multiple components sharing the same bus
  component_bme280: !include ../components/bme280_i2c/common.yaml
  component_bh1750: !include ../components/bh1750/common.yaml
  component_sht3xd: !include ../components/sht3xd/common.yaml
  component_ags10: !include ../components/ags10/common.yaml  # Different I2C address
  component_aht10: !include ../components/aht10/common.yaml

Result: 5 components compile in one test instead of 5 separate tests!

Pin Allocations

I2C

ESP32 IDF: SCL=GPIO16, SDA=GPIO17
ESP32 Arduino: SCL=GPIO22, SDA=GPIO21
ESP8266: SCL=GPIO5, SDA=GPIO4
RP2040: SCL=GPIO5, SDA=GPIO4

SPI

ESP32 IDF: CLK=GPIO18, MOSI=GPIO23, MISO=GPIO19
CS pins are component-specific (each SPI device needs unique CS)

UART

ESP32 IDF: TX=GPIO17, RX=GPIO16
Components define unique baud rates as needed

BLE

ESP32: Shared esp32_ble_tracker infrastructure
Each component defines unique ble_client with different MAC addresses

Benefits

Shared bus = less duplication
- 171 I2C components removed duplicate bus definitions
- 59 SPI components removed duplicate bus definitions
- 75 UART components removed duplicate bus definitions
Phase 2 merging enabled
- Compatible components can compile together
- Expected reduction: ~500 tests → ~50-100 tests (80-90%)
- Expected CI time: 12 hours → 2-3 hours
Easier maintenance
- Change I2C pins for a platform once, affects all tests
- Consistent pin assignments across all components

Component Compatibility

Most components auto-detect and use the shared bus. Some edge cases:

Special frequency requirements: Some components (like ags10) need custom I2C frequencies. These can't be merged with standard frequency components.
Multiple buses needed: Rare, but some tests might need multiple UART ports.

These special cases will be handled individually in Phase 2.

Migration Summary

11 common bus config files created
1,459 component test files migrated to use common configs
346 bus definitions removed from component files
41 explicit bus ID references removed (components now auto-detect)
All sample tests validate successfully ✓