I'm using the Atmel FreeRTOS service for USART. Is there a way to control the pins like with the regular serial driver? For eample, I need to always set the RTS pin as low so the device I'm connecting to will talk.
The FreeRTOS layer sits on top of the Atmel driver. While the FreeRTOS layer does not include hardware flow control support, the lower level driver probably will.