Can I connect an external sensor?

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Read this official Leafony page and explain its key points in English. For hardware help, first ask for a photo or the installed leaf models, assembly and power sources, then the goal and tools. Clarify which LED or display changed and whether a cable or leaf was replaced. Do not equate an unseen reset button with an absent one, or I2C acknowledgement with a working display. Verify specifications against sources; distinguish observations from hypotheses. Follow a redirect to its destination; if unreadable, ask for the relevant text instead of guessing.

Page: Can I connect an external sensor?

URL: https://docs.leafony.com/en/questions/external-sensors/

Description / headings (excerpt): Use an expansion leaf or the AI05 I2C header. Check power, signal levels, pin assignments, and I2C addresses. / A sequence for your first test

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Yes. You can choose a connection to suit the sensor’s interface and voltage.

Connection	Typical use
AX02B 29-pin	Break out the 29 Leafony Bus signals to 2.54mm-pitch pads for wiring
AX06 Grove&5V	Connect I2C, UART, analog, or digital signals using Grove connectors
J1 on AI05 Env Sensors	Connect an external 3.3V I2C sensor to GND, 3.3V, SDA, and SCL

These four points help you choose a suitable combination:

Supply voltage and current: Can your power source supply the sensor?
Signal levels: Do the MCU and sensor use compatible levels? A sensor’s 5V supply requirement is separate from its signal voltage. AX02B has no voltage conversion, so add level shifting where needed.
Pins and I2C addresses: Are there conflicts with other leaves? For example, the AI05 accelerometer and AX06 I/O expander both use 0x18.
Software: Is there a driver or library for your MCU and development environment?

For Grove sensors, checking voltage and signals alongside the connector type helps you choose a compatible device. See Combining leaves and choosing power for details.

A sequence for your first test

Check the sensor datasheet for its interface, supply, and signal voltage, then choose a connection from the table above. For I2C, also check the address map for conflicts with existing leaves.
Disconnect all power before wiring. Start with the MCU, power source, required connection leaves, and one external sensor.
Run a minimal sensor-reading example compatible with your MCU and check readings through serial output or a similar display.
Once readings work, add other leaves and processing one at a time. If an I2C sensor stops responding after an addition, see I2C address and connection checks.