afc

The S3C2440A's UART 0 and UART 1 support auto flow control with nRTS and nCTS signals. In case, it can be

connected to external UARTs. If users want to connect a UART to a Modem, disable auto flow control bit in

UMCONn register and control the signal of nRTS by software.

In AFC, nRTS depends on the condition of the receiver and nCTS signals control the operation of the transmitter.

The UART's transmitter transfers the data in FIFO only when nCTS signals are activated (in AFC, nCTS means

that other UART's FIFO is ready to receive data). Before the UART receives data, nRTS has to be activated when

its receive FIFO has a spare more than 32-byte and has to be inactivated when its receive FIFO has a spare under

32-byte (in AFC, nRTS means that its own receive FIFO is ready to receive data).