Open-Drain Mode Does Not Work When TXD is Configured as Output

When the USART TXD pin is configured as an output, it can drive the pin high regardless of whether the Open-Drain mode is enabled or not.

Work Around

Configure the TXD pin as an input by writing the corresponding bit in PORTx.DIR to ‘0’ when using Open-Drain mode.

Affected Silicon Revisions

Rev. A