Serial Class Reference

Serial interface. More...

#include <machine/serial.h>

Inheritance diagram for Serial:

Public Types
enum	ComPort {   COM1 = 0x3f8 ,   COM2 = 0x2f8 ,   COM3 = 0x3e8 ,   COM4 = 0x2e8 }
	COM-Port. More...
enum	BaudRate {   BAUD_300 = 384 ,   BAUD_600 = 192 ,   BAUD_1200 = 96 ,   BAUD_2400 = 48 ,   BAUD_4800 = 24 ,   BAUD_9600 = 12 ,   BAUD_19200 = 6 ,   BAUD_38400 = 3 ,   BAUD_57600 = 2 ,   BAUD_115200 = 1 }
	Transmission speed. More...
enum	DataBits {   DATA_5BIT = 0 ,   DATA_6BIT = 1 ,   DATA_7BIT = 2 ,   DATA_8BIT = 3 }
	Number of data bits per character. More...
enum	StopBits {   STOP_1BIT = 0 ,   STOP_1_5BIT = 4 ,   STOP_2BIT = 4 }
	Number of stop bits per character. More...
enum	Parity {   PARITY_NONE = 0 ,   PARITY_ODD = 8 ,   PARITY_EVEN = 24 ,   PARITY_MARK = 40 ,   PARITY_SPACE = 56 }
	parity bit More...

Public Member Functions
	Serial (ComPort port=COM1, BaudRate baud_rate=BAUD_115200, DataBits data_bits=DATA_8BIT, StopBits stop_bits=STOP_1BIT, Parity parity=PARITY_NONE)
	Constructor.
int	read (bool blocking=true)
	Read one byte from the serial interface.
int	write (char out, bool blocking=true)
	Write one byte to the serial interface.
bool	receiveInterrupt (bool enable)
	Activate or deactivate interrupts on data reception.

Protected Attributes
const ComPort	port
	Selected COM port.

Private Types
enum	RegisterIndex {   RECEIVE_BUFFER_REGISTER = 0 ,   TRANSMIT_BUFFER_REGISTER = 0 ,   INTERRUPT_ENABLE_REGISTER = 1 ,   DIVISOR_LOW_REGISTER = 0 ,   DIVISOR_HIGH_REGISTER = 1 ,   INTERRUPT_IDENT_REGISTER = 2 ,   FIFO_CONTROL_REGISTER = 2 ,   LINE_CONTROL_REGISTER = 3 ,   MODEM_CONTROL_REGISTER = 4 ,   LINE_STATUS_REGISTER = 5 ,   MODEM_STATUS_REGISTER = 6 }
	register index More...
enum	RegisterMask : uint8_t {   RECEIVED_DATA_AVAILABLE = 1 << 0 ,   TRANSMITTER_HOLDING_REGISTER_EMPTY = 1 << 1 ,   RECEIVER_LINE_STATUS = 1 << 2 ,   MODEM_STATUS = 1 << 3 ,   INTERRUPT_PENDING = 1 << 0 ,   INTERRUPT_ID_0 = 1 << 1 ,   INTERRUPT_ID_1 = 1 << 2 ,   ENABLE_FIFO = 1 << 0 ,   CLEAR_RECEIVE_FIFO = 1 << 1 ,   CLEAR_TRANSMIT_FIFO = 1 << 2 ,   DMA_MODE_SELECT = 1 << 3 ,   TRIGGER_RECEIVE = 1 << 6 ,   WORD_LENGTH_SELECT_0 = 1 << 0 ,   WORD_LENGTH_SELECT_1 = 1 << 1 ,   NUMBER_OF_STOP_BITS = 1 << 2 ,   PARITY_ENABLE = 1 << 3 ,   EVEN_PARITY_SELECT = 1 << 4 ,   STICK_PARITY = 1 << 5 ,   SET_BREAK = 1 << 6 ,   DIVISOR_LATCH_ACCESS_BIT = 1 << 7 ,   DATA_TERMINAL_READY = 1 << 0 ,   REQUEST_TO_SEND = 1 << 1 ,   OUT_1 = 1 << 2 ,   OUT_2 = 1 << 3 ,   LOOP = 1 << 4 ,   DATA_READY = 1 << 0 ,   OVERRUN_ERROR = 1 << 1 ,   PARITY_ERROR = 1 << 2 ,   FRAMING_ERROR = 1 << 3 ,   BREAK_INTERRUPT = 1 << 4 ,   TRANSMITTER_HOLDING_REGISTER = 1 << 5 ,   TRANSMITTER_EMPTY = 1 << 6 ,   DELTA_CLEAR_TO_SEND = 1 << 0 ,   DELTA_DATA_SET_READY = 1 << 1 ,   TRAILING_EDGE_RING_INDICATOR = 1 << 2 ,   DELTA_DATA_CARRIER_DETECT = 1 << 3 ,   CLEAR_TO_SEND = 1 << 4 ,   DATA_SET_READY = 1 << 5 ,   RING_INDICATOR = 1 << 6 ,   DATA_CARRIER_DETECT = 1 << 7 }
	Mask for the respective register. More...

Private Member Functions
char	readReg (RegisterIndex reg)
	Read value from register.
void	writeReg (RegisterIndex reg, char out)
	Write value to register.

Detailed Description

Serial interface.

This class provides a serial interface (COM1 - COM4) for communication with the outside world.

The first IBM PC used the external chip 8250 UART, whereas, in today's systems, this functionality is commonly integrated into the southbridge, but remained compatible.

See also

PC8250A Data Sheet (Registers on page 11)

PC16550D Data Sheet (Successor, for optional FIFO buffer, page 16)

Member Enumeration Documentation

ComPort

enum Serial::ComPort

COM-Port.

The serial interface and its hardware addresses. Modern desktop PCs have, at most, a single, physical COM-port (COM1)

Enumerator
COM1
COM2
COM3
COM4

BaudRate

enum Serial::BaudRate

Transmission speed.

The unit Baud describes the transmission speed in number of symbols per seconds. 1 Baud therefore equals the transmission of 1 symbol per second. The possible Baud rates are whole-number dividers of the clock frequency of 115200 Hz..

Enumerator
BAUD_300
BAUD_600
BAUD_1200
BAUD_2400
BAUD_4800
BAUD_9600
BAUD_19200
BAUD_38400
BAUD_57600
BAUD_115200

DataBits

enum Serial::DataBits

Number of data bits per character.

Enumerator
DATA_5BIT
DATA_6BIT
DATA_7BIT
DATA_8BIT

StopBits

enum Serial::StopBits

Number of stop bits per character.

Enumerator
STOP_1BIT
STOP_1_5BIT
STOP_2BIT

Parity

enum Serial::Parity

parity bit

Enumerator
PARITY_NONE
PARITY_ODD
PARITY_EVEN
PARITY_MARK
PARITY_SPACE

RegisterIndex

enum Serial::RegisterIndex

private

register index

Enumerator
RECEIVE_BUFFER_REGISTER	read only
TRANSMIT_BUFFER_REGISTER	write only
INTERRUPT_ENABLE_REGISTER
DIVISOR_LOW_REGISTER
DIVISOR_HIGH_REGISTER
INTERRUPT_IDENT_REGISTER	read only
FIFO_CONTROL_REGISTER	write only – 16550 and newer (esp. not 8250a)
LINE_CONTROL_REGISTER	highest-order bit is DLAB (see above)
MODEM_CONTROL_REGISTER
LINE_STATUS_REGISTER
MODEM_STATUS_REGISTER

RegisterMask

enum Serial::RegisterMask : uint8_t

private

Mask for the respective register.

Enumerator
RECEIVED_DATA_AVAILABLE
TRANSMITTER_HOLDING_REGISTER_EMPTY
RECEIVER_LINE_STATUS
MODEM_STATUS
INTERRUPT_PENDING	0 means interrupt pending
INTERRUPT_ID_0
INTERRUPT_ID_1
ENABLE_FIFO	0 means disabled ^= conforming to 8250a
CLEAR_RECEIVE_FIFO
CLEAR_TRANSMIT_FIFO
DMA_MODE_SELECT
TRIGGER_RECEIVE
WORD_LENGTH_SELECT_0
WORD_LENGTH_SELECT_1
NUMBER_OF_STOP_BITS
PARITY_ENABLE
EVEN_PARITY_SELECT
STICK_PARITY
SET_BREAK
DIVISOR_LATCH_ACCESS_BIT
DATA_TERMINAL_READY
REQUEST_TO_SEND
OUT_1
OUT_2
LOOP
DATA_READY
OVERRUN_ERROR
PARITY_ERROR
FRAMING_ERROR
BREAK_INTERRUPT
TRANSMITTER_HOLDING_REGISTER
TRANSMITTER_EMPTY
DELTA_CLEAR_TO_SEND
DELTA_DATA_SET_READY
TRAILING_EDGE_RING_INDICATOR
DELTA_DATA_CARRIER_DETECT
CLEAR_TO_SEND
DATA_SET_READY
RING_INDICATOR
DATA_CARRIER_DETECT

Constructor & Destructor Documentation

Serial()

Serial::Serial ( ComPort  port = COM1, BaudRate  baud_rate = BAUD_115200, DataBits  data_bits = DATA_8BIT, StopBits  stop_bits = STOP_1BIT, Parity  parity = PARITY_NONE  )

explicit

Constructor.

Creates a Serial object that encapsulates the used COM port, as well as the parameters used for the serial connection. Default values are 8N1 (8 bit, no parity bit, one stop bit) with 115200 Baud using COM1.

Member Function Documentation

readReg()

char Serial::readReg ( RegisterIndex  reg )

private

Read value from register.

Parameters

reg	Register index

Returns

The value read from register

writeReg()

void Serial::writeReg ( RegisterIndex  reg, char  out  )

private

Write value to register.

Parameters

reg	Register index
out	value to be written

read()

int Serial::read

(

bool

blocking = true

)

Read one byte from the serial interface.

Parameters

blocking

If set, read() blocks until one byte was read

Returns

Value read from serial interface (or -1 if non-blocking and no data ready)

write()

int Serial::write	(	char	out,
		bool	blocking = true
	)

Write one byte to the serial interface.

Parameters

out	Byte to be written
blocking	If set, write() blocks until the byte was written

Returns

Byte written (or -1 if writing byte failed)

receiveInterrupt()

bool Serial::receiveInterrupt

(

bool

enable

)

Activate or deactivate interrupts on data reception.

Calling this function reconfigures the respective register and flushes the receive buffer.

Optional:

Implement Method.

Note

In addition to the (obvious) modification in the INTERRUPT_ENABLE_REGISTER, the bit OUT_2 must be set in the MODEM_CONTROL_REGISTER to enable interrupts.

Parameters

enable

If true, interrupts will be enabled, otherwise disabled.

Returns

Previous interrupt state.

Member Data Documentation

port

const ComPort Serial::port

protected

Selected COM port.

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The documentation for this class was generated from the following files:

• machine/serial.h
• machine/serial.cc