ReimuNotMoe edited a comment on issue #2988: URL: https://github.com/apache/incubator-nuttx/issues/2988#issuecomment-798922955
> Hi @ReimuNotMoe what device are you trying to dump? Do you have a Logic Analyzer to see the bus? Even a "cheaper" logic analyzer can do the trick: https://acassis.wordpress.com/2015/07/19/sigrok-and-a-cheap-saleae-clone-can-save-your-life-i-meant-your-time/ > This way you can compare the i2ctool command from NuttX against STM32 HAL and the Raspberry Pi i2ctool. I bought a DSLogic Plus logic analyzer and used it to inspect the i2c lines. **Edit: I selected wrong channels in the previous edit. Here are the correct results.** It seems that `i2c` is reading "correct" data, I don't know why. Nuttx dumping an EPSON RTC, all 0xff:   i2ctool output when dumping a MCP23017 I/O expander, garbled data:   Raspi dumping the same EPSON RTC, everything fine:   Raspi dumping the same MCP23017 I/O expander, everything fine:   ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
