Runtime configuration is achieved by exchanging data structures with the driver via the cyg_io_set_config() and cyg_io_get_config() functions.

typedef struct {
    cyg_serial_baud_rate_t baud;
    cyg_serial_stop_bits_t stop;
    cyg_serial_parity_t parity;
    cyg_serial_word_length_t word_length;
    cyg_uint32 flags;
} cyg_serial_info_t;

The field word_length contains the number of data bits per word (character). This must be one of the values:

CYGNUM_SERIAL_WORD_LENGTH_5
CYGNUM_SERIAL_WORD_LENGTH_6
CYGNUM_SERIAL_WORD_LENGTH_7
CYGNUM_SERIAL_WORD_LENGTH_8

The field baud contains a baud rate selection. If the configuration does not implement the CYGINT_IO_SERIAL_BAUD_ARBITRARY interface support for arbitrary baud rate values then this field must be one of the values:

CYGNUM_SERIAL_BAUD_50
CYGNUM_SERIAL_BAUD_75
CYGNUM_SERIAL_BAUD_110
CYGNUM_SERIAL_BAUD_134_5
CYGNUM_SERIAL_BAUD_150
CYGNUM_SERIAL_BAUD_200
CYGNUM_SERIAL_BAUD_300
CYGNUM_SERIAL_BAUD_600
CYGNUM_SERIAL_BAUD_1200
CYGNUM_SERIAL_BAUD_1800
CYGNUM_SERIAL_BAUD_2400
CYGNUM_SERIAL_BAUD_3600
CYGNUM_SERIAL_BAUD_4800
CYGNUM_SERIAL_BAUD_7200
CYGNUM_SERIAL_BAUD_9600
CYGNUM_SERIAL_BAUD_14400
CYGNUM_SERIAL_BAUD_19200
CYGNUM_SERIAL_BAUD_38400
CYGNUM_SERIAL_BAUD_57600
CYGNUM_SERIAL_BAUD_115200
CYGNUM_SERIAL_BAUD_234000

For configurations where CYGINT_IO_SERIAL_BAUD_ARBITRARY is enabled then the manifests above define the respective baud rate, but the underlying device driver is capable of accepting arbitrary baud rate values as required. e.g. 76800.

The field stop contains the number of stop bits. This must be one of the values:

CYGNUM_SERIAL_STOP_1
CYGNUM_SERIAL_STOP_1_5
CYGNUM_SERIAL_STOP_2

	Note
	On most hardware, a selection of 1.5 stop bits is only valid if the word (character) length is 5.

The field parity contains the parity mode. This must be one of the values:

CYGNUM_SERIAL_PARITY_NONE
CYGNUM_SERIAL_PARITY_EVEN
CYGNUM_SERIAL_PARITY_ODD
CYGNUM_SERIAL_PARITY_MARK
CYGNUM_SERIAL_PARITY_SPACE

The field flags is a bitmask which controls the behavior of the serial device driver. It should be built from the values CYG_SERIAL_FLAGS_xxx defined below:

#define CYG_SERIAL_FLAGS_RTSCTS 0x0001

If this bit is set then the port is placed in “hardware handshake” mode. In this mode, the CTS and RTS pins control when data is allowed to be sent/received at the port. This bit is ignored if the hardware does not support this level of handshake.

typedef struct {
    cyg_int32 rx_bufsize;
    cyg_int32 rx_count;
    cyg_int32 tx_bufsize;
    cyg_int32 tx_count;
} cyg_serial_buf_info_t;     

The field rx_bufsize contains the total size of the incoming data buffer. This is set to zero on devices that do not support buffering (i.e. polled devices).

The field rx_count contains the number of bytes currently occupied in the incoming data buffer. This is set to zero on devices that do not support buffering (i.e. polled devices).

The field tx_bufsize contains the total size of the transmit data buffer. This is set to zero on devices that do not support buffering (i.e. polled devices).

The field tx_count contains the number of bytes currently occupied in the transmit data buffer. This is set to zero on devices that do not support buffering (i.e. polled devices).

Runtime configuration is achieved by exchanging data structures with the driver via the cyg_io_set_config() and cyg_io_get_config() functions.

typedef struct {
    cyg_uint32 tty_out_flags;
    cyg_uint32 tty_in_flags;
} cyg_tty_info_t;

The field tty_out_flags is used to control what happens to data as it is send to the serial port. It contains a bitmap comprised of the bits as defined by the CYG_TTY_OUT_FLAGS_xxx values below.

#define CYG_TTY_OUT_FLAGS_CRLF 0x0001 // Map '\n' => '\r\n' on output

If this bit is set in tty_out_flags, any occurrence of the character "\n" will be replaced by the sequence "\r\n" before being sent to the device.

The field tty_in_flags is used to control how data is handled as it comes from the serial port. It contains a bitmap comprised of the bits as defined by the CYG_TTY_IN_FLAGS_xxx values below.

#define CYG_TTY_IN_FLAGS_CR 0x0001 // Map '\r' => '\n' on input

If this bit is set in tty_in_flags, the character "\r" (“return” or “enter” on most keyboards) will be mapped to "\n".

#define CYG_TTY_IN_FLAGS_CRLF 0x0002 // Map '\r\n' => '\n' on input

If this bit is set in tty_in_flags, the character sequence "\r\n" (often sent by DOS/Windows based terminals) will be mapped to "\n".

#define CYG_TTY_IN_FLAGS_ECHO 0x0004 // Echo characters as processed

If this bit is set in tty_in_flags, characters will be echoed back to the serial port as they are processed.

#define CYG_TTY_IN_FLAGS_BINARY 0x0008 // No input processing

If this bit is set in tty_in_flags, the input will not be manipulated in any way before being placed in the user‚s buffer.

cyg_io_read(handle, buf, len)

This function is used to read data from the device. In the default case, data is read until an end-of-line character ("\n" or "\r") is read. Additionally, the characters are echoed back to the [terminal] device. Minimal editing of the input is also supported.

	Note
	When connecting to a remote target via GDB it is not possible to provide console input while GDB is connected. The GDB remote protocol does not support input. Users must disconnect from GDB if this functionality is required.

cyg_io_write(handle, buf, len)

This function is used to send data to the device. In the default case, the end-of-line character "\n" is replaced by the sequence "\r\n".

cyg_io_get_config(handle, key, buf, len)

This function is used to get information about the channel‚s configuration at runtime.

Serial driver keys (see above) may also be specified in which case the call is passed directly to the serial driver.

cyg_io_set_config(handle, key, buf, len)

This function is used to modify the channel‚s configuration at runtime.

Serial driver keys (see above) may also be specified in which case the call is passed directly to the serial driver.