TMP421 on Arduino YUN

[FredSpringer]

Unlike on an Arduino Uno, the SDA and SCL signals on the Arduino Yun are not located at analog ports 4 and 5. SDA is now on digital port 2 and SCL is now on digital port 3 on the Yun microprocessor. This means a TMP421 sensor will not plug into the last 4 analog ports on a Yun. The clock and data signals are moved to the digital ports.