Raspberry Pi dimmer via I2C — i2cdetect shows nothing

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Right, so I’ve been trying to get DimmerLink working on a Raspberry Pi Zero 2W over I2C. Wired up SDA to GPIO2, SCL to GPIO3, 3.3V and GND. I2C is enabled in raspi-config.

Ran i2cdetect and got absolutely nothing:

pi@pizero:~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

All dashes. No 0x50, no nothing.

I’ve double-checked the wiring with a multimeter — continuity is fine on SDA and SCL. Tried swapping to a different DimmerLink module, same result. Plugged in an MCP23017 on the same bus just to rule out a Pi issue — that shows up at 0x20 immediately.

So the Pi’s I2C bus is working, the wiring is correct, but DimmerLink is invisible. Am I missing something obvious here?

2

Sorted! That was exactly it — UART mode by default. Wouldn’t have guessed that in a million years.

Connected via UART with minicom, sent 0x02 0x5B, power cycled the module, and:

pi@pizero:~ $ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

There’s 0x50, clear as day. Sending brightness commands from Python now and the lamp responds instantly.

Should have checked the I2C documentation page more carefully — I see now it mentions the UART default mode right at the top. Cheers for the quick response.

[SOLVED]