MSP430F5438A: IO configuration of MSP430f5438A

Hi Chandrashekhar,

One can emulate an open drain behavior by setting the output register of a GPIO to low, and switch it by using the direction register between input and output. If set to output it will actively pull the signal low and open the current path to GND, like an active open drain, while in input direction it will be high impedance pulled up by the external signal, like an inactive open drain.

The important limitation in comparison with a true open drain is the pulling signal level does not have to exceed the MSP430 supply voltage level, as then the clamping diodes would short the signal, while a true open drain can take higher signals then the supply voltage.

BR,

Leo