ESP32 pin & I²C address conflict planner

Two sensors can each work perfectly and still refuse to work together. Pick a board and the parts you intend to use — this checks for I²C addresses that collide, more UART devices than the chip has UARTs, and more analog inputs than it has usable ADC pins.

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Known I²C address collisions

Every part below shares a default address with at least one other part in this index. Where both addresses are fixed in silicon, no amount of configuration helps — the fix is a TCA9548A multiplexer or the ESP32's second I²C bus.

Address	Parts	Can it be resolved?
0x29	TSL2591 HDR Ambient Lux Sensor — fixed TCS34725 RGB Color Sensor with IR Filter — fixed VL53L0X Time-of-Flight Distance Sensor — adjustable	No — both fixed. Needs a multiplexer or a second bus.
0x38	AHT10 Precision Temp & Humidity Sensor — fixed AHT20 Humidity & Temperature Sensor — fixed	No — both fixed. Needs a multiplexer or a second bus.
0x40	INA219 DC Voltage & Current Sensor — adjustable INA226 Bi-Directional Power Monitor — adjustable HTU21D Temp & Humidity Sensor — fixed HDC1080 Temp & Humidity Sensor — fixed	No — both fixed. Needs a multiplexer or a second bus.
0x69	SEN55 Environmental Sensor Node — fixed SPS30 Laser Particulate Sensor — fixed	No — both fixed. Needs a multiplexer or a second bus.
0x20	MCP23017 16-Bit I2C GPIO Expander — adjustable PCF8574 8-bit I2C GPIO Expander — adjustable	Yes — at least one is strappable. A0-A2 strapping selects 0x20-0x27.
0x39	APDS9960 Proximity & Gesture Sensor — fixed TSL2561 Digital Lux Sensor — adjustable	Yes — at least one is strappable. ADDR pin selects 0x29, 0x39 or 0x49.
0x3C	SSD1306 0.96 OLED Display (128x64) — adjustable SH1106 1.3 Inch OLED Display (128x64) — adjustable	Yes — at least one is strappable. Usually 0x3C; some modules expose a 0x3D jumper.
0x44	SHT40 High-Accuracy Temp Sensor — fixed SHT31 Digital Temp & Humidity Sensor — adjustable OPT3001 Precision Ambient Light Sensor — adjustable	Yes — at least one is strappable. ADDR pin selects 0x44 or 0x45.
0x48	ADS1115 16-bit 4-Channel Precision ADC — adjustable TMP117 Precision Temperature Sensor — adjustable	Yes — at least one is strappable. ADDR pin selects 0x48-0x4B.
0x53	LTR390 UV & Ambient Light Sensor — fixed ScioSense ENS160 Multi-Gas Sensor — adjustable	Yes — at least one is strappable. ADDR pin selects 0x52 or 0x53.
0x5A	MLX90614 Contactless IR Thermal Sensor — adjustable CCS811 eCO2 & TVOC Air Sensor — adjustable	Yes — at least one is strappable. Ships at 0x5A; reprogrammable in EEPROM.
0x76	BME680 Environmental & Gas Sensor — adjustable BME280 Temp Humidity & Pressure Sensor — adjustable BMP280 Barometric Pressure & Temp Sensor — adjustable	Yes — at least one is strappable. SDO pin selects 0x76 or 0x77.
0x77	Bosch BME688 AI Gas Sensor with BSEC — adjustable BMP388 Precision Barometric Pressure Sensor — adjustable Bosch BMP390 Precision Barometer Sensor — adjustable DPS310 Precision Barometric Sensor — adjustable	Yes — at least one is strappable. SDO pin selects 0x76 or 0x77; Adafruit boards ship at 0x77.

Addresses come from the configurations published on each device page and are cross-checked against them at build time. Parts without a published config are not listed here, which means absence is not evidence of no clash — flash with i2c: scan: true and read the boot log.