PS2Controller Namespace Reference

PS/2 Controller. More...

Enumerations
enum	Status {   HAS_OUTPUT = 1 << 0 , INPUT_PENDING = 1 << 1 , SYSTEM_FLAG = 1 << 2 , IS_COMMAND = 1 << 3 ,   IS_MOUSE = 1 << 5 , TIMEOUT_ERROR = 1 << 6 , PARITY_ERROR = 1 << 7 }
	Flags in the PS/2 controller status register. More...
enum	KeyboardCommand : uint8_t {   KEYBOARD_SET_LED = 0xed , KEYBOARD_SEND_ECHO = 0xee , KEYBOARD_SET_SPEED = 0xf3 , KEYBOARD_ENABLE = 0xf4 ,   KEYBOARD_DISABLE = 0xf5 , KEYBOARD_SET_DEFAULT = 0xf6 }
	Commands to be send to the Keyboard. More...
enum	Reply { ACK = 0xfa , RESEND = 0xfe , ECHO = 0xee }
	Replies. More...
enum	ControllerCommand {   CONTROLLER_GET_COMMAND_BYTE = 0x20 , CONTROLLER_SET_COMMAND_BYTE = 0x60 , CONTROLLER_MOUSE_DISABLE = 0xa7 , CONTROLLER_MOUSE_ENABLE = 0xa8 ,   CONTROLLER_KEYBOARD_DISABLE = 0xad , CONTROLLER_KEYBOARD_ENABLE = 0xae , CONTROLLER_SEND_TO_MOUSE = 0xd4 }
	Commands for the PS/2 Controller. More...
enum	Delay { DELAY_250MS = 0 , DELAY_500MS = 1 , DELAY_750MS = 2 , DELAY_1000MS = 3 }
	Delay before the keyboard starts repeating sending a pressed key. More...
enum	Speed {   SPEED_30_0CPS = 0x00 , SPEED_26_7CPS = 0x01 , SPEED_24_0CPS = 0x02 , SPEED_21_8CPS = 0x03 ,   SPEED_20_7CPS = 0x04 , SPEED_18_5CPS = 0x05 , SPEED_17_1CPS = 0x06 , SPEED_16_0CPS = 0x07 ,   SPEED_15_0CPS = 0x08 , SPEED_13_3CPS = 0x09 , SPEED_12_0CPS = 0x0a , SPEED_10_9CPS = 0x0b ,   SPEED_10_0CPS = 0x0c , SPEED_09_2CPS = 0x0d , SPEED_08_6CPS = 0x0e , SPEED_08_0CPS = 0x0f ,   SPEED_07_5CPS = 0x10 , SPEED_06_7CPS = 0x11 , SPEED_06_0CPS = 0x12 , SPEED_05_5CPS = 0x13 ,   SPEED_05_0CPS = 0x14 , SPEED_04_6CPS = 0x15 , SPEED_04_3CPS = 0x16 , SPEED_04_0CPS = 0x17 ,   SPEED_03_7CPS = 0x18 , SPEED_03_3CPS = 0x19 , SPEED_03_0CPS = 0x1a , SPEED_02_7CPS = 0x1b ,   SPEED_02_5CPS = 0x1c , SPEED_02_3CPS = 0x1d , SPEED_02_1CPS = 0x1e , SPEED_02_0CPS = 0x1f }
	Repeat Rate of Characters. More...
enum	LED { LED_SCROLL_LOCK = 1 << 0 , LED_NUM_LOCK = 1 << 1 , LED_CAPS_LOCK = 1 << 2 }
	Keyboard LEDs. More...

Functions
void	init ()
	Initialization of connected devices.
bool	fetch (Key &pressed)
	Retrieve the keyboard event.
void	setRepeatRate (Speed speed, Delay delay)
	Configure the repeat rate of the keyboard.
void	setLed (enum LED led, bool on)
	Enable or disable a keyboard LED.
void	drainBuffer ()
	Empties the keyboard buffer.
bool	isPressed (Key::Scancode key)
	Check if a key is currently pressed.

Detailed Description

PS/2 Controller.

Initializes the PS/2 devices (Keyboard and optional Mouse), and determines both the scan code and ASCII character of a pressed key from the transmitted make and break codes using the KeyDecoder.

Note

This controller is also known as Intel 8042 (nowadays integrated in the mainboard) or Keyboard Controller. But to avoid confusion with the actual Keyboard and since we use the PS/2-compatible mode to support the Mouse as well, the name PS/2 Controller was chosen for the sake of simplicity.

Since modern PCs sometimes don't have an PS/2 connector, USB keyboards and mice are emulated as PS/2 device with USB Legacy Support.

Enumeration Type Documentation

ControllerCommand

enum PS2Controller::ControllerCommand

Commands for the PS/2 Controller.

These commands are processed by the controller and not send to keyboard/mouse. They have to be written into the command register.

Enumerator
CONTROLLER_GET_COMMAND_BYTE	Read Command Byte of PS/2 Controller.
CONTROLLER_SET_COMMAND_BYTE	Write Command Byte of PS/2 Controller.
CONTROLLER_MOUSE_DISABLE	Disable mouse interface.
CONTROLLER_MOUSE_ENABLE	Enable mouse interface.
CONTROLLER_KEYBOARD_DISABLE	Disable keyboard interface.
CONTROLLER_KEYBOARD_ENABLE	Enable keyboard interface.
CONTROLLER_SEND_TO_MOUSE	Send parameter to mouse device.

Delay

enum PS2Controller::Delay

Delay before the keyboard starts repeating sending a pressed key.

Enumerator
DELAY_250MS	Delay of 0.25s.
DELAY_500MS	Delay of 0.5s.
DELAY_750MS	Delay of 0.75s.
DELAY_1000MS	Delay of 1s.

KeyboardCommand

enum PS2Controller::KeyboardCommand : uint8_t

Commands to be send to the Keyboard.

Enumerator
KEYBOARD_SET_LED	Set the LED (according to the following parameter byte)
KEYBOARD_SEND_ECHO	Send an echo packet.
KEYBOARD_SET_SPEED	Set the repeat rate (according to the following parameter byte)
KEYBOARD_ENABLE	Enable Keyboard.
KEYBOARD_DISABLE	Disable Keyboard.
KEYBOARD_SET_DEFAULT	Load defaults.

LED

enum PS2Controller::LED

Keyboard LEDs.

Enumerator
LED_SCROLL_LOCK	Scroll Lock.
LED_NUM_LOCK	Num Lock.
LED_CAPS_LOCK	Caps Lock.

Reply

enum PS2Controller::Reply

Replies.

Enumerator
ACK	Acknowledgement.
RESEND	Request to resend (not required to implement)
ECHO	Echo answer.

Speed

enum PS2Controller::Speed

Repeat Rate of Characters.

See also

The PS/2 Keyboard Interface

Enumerator
SPEED_30_0CPS	30 characters per second
SPEED_26_7CPS	26.7 characters per second
SPEED_24_0CPS	24 characters per second
SPEED_21_8CPS	12.8 characters per second
SPEED_20_7CPS	20.7 characters per second
SPEED_18_5CPS	18.5 characters per second
SPEED_17_1CPS	17.1 characters per second
SPEED_16_0CPS	16 characters per second
SPEED_15_0CPS	15 characters per second
SPEED_13_3CPS	13.3 characters per second
SPEED_12_0CPS	12 characters per second
SPEED_10_9CPS	10.9 characters per second
SPEED_10_0CPS	10 characters per second
SPEED_09_2CPS	9.2 characters per second
SPEED_08_6CPS	8.6 characters per second
SPEED_08_0CPS	8 characters per second
SPEED_07_5CPS	7.5 characters per second
SPEED_06_7CPS	6.7 characters per second
SPEED_06_0CPS	6 characters per second
SPEED_05_5CPS	5.5 characters per second
SPEED_05_0CPS	5 characters per second
SPEED_04_6CPS	4.6 characters per second
SPEED_04_3CPS	4.3 characters per second
SPEED_04_0CPS	4 characters per second
SPEED_03_7CPS	3.7 characters per second
SPEED_03_3CPS	3.3 characters per second
SPEED_03_0CPS	3 characters per second
SPEED_02_7CPS	2.7 characters per second
SPEED_02_5CPS	2.5 characters per second
SPEED_02_3CPS	2.3 characters per second
SPEED_02_1CPS	2.1 characters per second
SPEED_02_0CPS	2 characters per second

Status

enum PS2Controller::Status

Flags in the PS/2 controller status register.

Enumerator
HAS_OUTPUT	Output buffer non-empty?
INPUT_PENDING	Is input buffer full?
SYSTEM_FLAG	set on soft reset, cleared on power up
IS_COMMAND	Is command Byte? (otherwise data)
IS_MOUSE	Mouse output has data.
TIMEOUT_ERROR	Timeout error.
PARITY_ERROR	Parity error.

Function Documentation

drainBuffer()

void PS2Controller::drainBuffer

(

)

Empties the keyboard buffer.

The keyboard may not send any interrupts if the buffer is not empty. To prevent unhandled keystrokes (for example during boot) the buffer should be emptied once right before allowing keyboard interrupts (even if keystrokes might be lost).

fetch()

bool PS2Controller::fetch

(

Key &

pressed

)

Retrieve the keyboard event.

Retrieves make and brake events from the keyboard. If a valid (non special) key was pressed, the scan code is determined using KeyDecoder::decode into a Key object. Events on special keys like Shift, Alt, CapsLock etc. are stored (in KeyDecoder) and applied on subsequent keystrokes, while no valid key is retrieved.

Mouse events are ignored.

Parameters

pressed

Reference to an object which will contain the pressed Key on success

Returns

true if a valid key was decoded

init()

void PS2Controller::init

(

)

Initialization of connected devices.

All status LEDs of the keyboard are switched off and the repetition rate is set to maximum speed.

isPressed()

bool PS2Controller::isPressed

(

Key::Scancode

key

)

Check if a key is currently pressed.

Parameters

key	Scancode of the key

Returns

true if pressed

setLed()

void PS2Controller::setLed	(	enum LED	led,
		bool	on
	)

Enable or disable a keyboard LED.

Parameters

led	LED to enable or disable
on	true will enable the specified LED, false disable

setRepeatRate()

void PS2Controller::setRepeatRate	(	Speed	speed,
		Delay	delay
	)

Configure the repeat rate of the keyboard.

Parameters

delay	configures how long a key must be pressed before the repetition begins.
speed	determines how fast the key codes should follow each other. Valid values are between 0 (30 characters per second) and 31 (2 characters per second).