Why might i2cdetect show some addresses as "--" even though devices are connected, and how can this be explained?

hard🧠 Conceptual Q10 of 15

Raspberry Pi - I2C Communication

Why might i2cdetect show some addresses as "--" even though devices are connected, and how can this be explained?

AThe Raspberry Pi I2C driver is not installed

BThe I2C bus is physically disconnected

CDevices may not respond to general call or probing; some devices ignore scan probes

DThe scan command was run without <code>sudo</code>

Step-by-Step Solution

Solution:

Step 1: Understand device behavior on I2C bus
Some I2C devices do not respond to address probing by i2cdetect and thus show as "--" despite being connected.
Step 2: Differentiate from hardware or permission issues
Physical disconnection or missing drivers cause different errors; running without sudo causes permission errors, not silent "--".
Final Answer:
Devices may not respond to general call or probing; some devices ignore scan probes -> Option C
Quick Check:
Some devices ignore probes = "--" despite connection [OK]

Quick Trick: Some devices ignore probes; "--" doesn't always mean no device [OK]

Common Mistakes:

MISTAKES

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