สแกนหาที่อยู่ I2C

Before coding a sensor you need its address. An I2C scanner sketch finds every device on the bus for you. 🔍

Two devices with the same address will clash on the bus. Scanning first tells you what is there and warns of conflicts.

A datasheet lists a default address, but solder jumpers can change it. Scanning gives you the real, current value every time.

The scanner tries every address from 1 to 127 and checks who answers. Each reply means a live device sits at that spot.

To test one address you open a message with beginTransmission. It targets the device without sending real data yet.

Calling endTransmission returns 0 if a device acknowledged. Any other number means nobody answered at that address.

Wrap the test in a loop that walks from 1 to 127, checking each address once and noting which ones reply.

When a device acknowledges, print its address to the Serial Monitor so you can copy it straight into your real sketch.

I2C addresses are usually shown in hex, like 0x27 or 0x3C. Printing with HEX matches the format libraries expect.

An empty scan usually means missing pull-ups, swapped SDA and SCL, or no power. Check the wiring and try again.

Make scanning a habit. It confirms wiring works and hands you the exact address before you write any sensor code. 🛠️

What does endTransmission returning 0 mean during a scan?

You can now scan the bus, walk addresses 1 to 127, and print the hex address of every device before writing real code. ✅