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# I²C Debugging Tips
The EC codebase has functionality to help you debug I²C errors without pulling
out the scope. Some of the debug functionality is disabled by default to save
space, but can be enabled with the `CONFIG_I2C_DEBUG` option.
## Tracing
You can use the `i2ctrace` command to monitor (ranges of) addresses:
```
i2ctrace [list
| disable <id>
| enable <port> <address>
| enable <port> <address-low> <address-high>]
```
For example:
```
> i2ctrace enable 0 0x10 0x30
> i2ctrace enable 1 0x20
> i2ctrace list
id port address
-- ---- -------
0 0 0x10 to 0x30
1 1 0x40 to 0x50
... debug spam may follow ...
i2c: 1:0x20 wr 0x10 rd 0x01 0x00
i2c: 1:0x20 wr 0x10 0x01 0x00
...
> i2ctrace disable 1
> i2ctrace list
id port address
-- ---- -------
0 0 0x10 to 0x30
```
A maximum of 8 debug entries are supported at a single time.
Note that `i2ctrace enable` will merge debug entries when possible:
```
> i2ctrace enable 0 0x10 0x30
> i2ctrace enable 0 0x40 0x50
> i2ctrace enable 0 0x31 0x3f
> i2ctrace list
id port address
-- ---- -------
0 0 0x10 to 0x50
```
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