PS/2 Library

PS/2 Library

The mikroPascal PRO for ARM provides a library for communication with the common PS/2 keyboard.

Important :

The library does not utilize interrupts for data retrieval, and requires the oscillator clock to be at least 6MHz.
The pins to which a PS/2 keyboard is attached should be connected to the pull-up resistors.
Although PS/2 is a two-way communication bus, this library does not provide MCU-to-keyboard communication; e.g. pressing the Caps Lock key will not turn on the Caps Lock LED.

External dependencies of PS/2 Library

Stellaris

The following variables must be defined in all projects using PS/2 Library:	Description :	Example :
`var PS2_Data : sbit; sfr; external;`	PS/2 Data line.	`var PS2_Data : sbit at GPIO_PORTD_DATA0_bit;`
`var PS2_Clock : sbit; sfr; external;`	PS/2 Clock line.	`var PS2_Clock : sbit at GPIO_PORTD_DATA1_bit;`
`var PS2_Data_Direction : sbit; sfr; external;`	Direction of the PS/2 Data pin.	`var PS2_Data_Direction : sbit at GPIO_PORTD_DIR0_bit;`
`var PS2_Clock_Direction : sbit; sfr; external;`	Direction of the PS/2 Clock pin.	`var PS2_Clock_Direction : sbit at GPIO_PORTD_DIR1_bit;`

MSP432

The following variables must be defined in all projects using PS/2 Library:	Description :	Example :
`var PS2_Data : sbit; sfr; external;`	PS/2 Data line.	`var PS2_Data : sbit at DIO_P6OUT.B0;`
`var PS2_Clock_Input : sbit; sfr; external;`	PS/2 Clock Input line.	`var PS2_Clock_Input : sbit at DIO_P6IN.B1;`
`var PS2_Clock_Output : sbit; sfr; external;`	PS/2 Clock Output line.	`var PS2_Clock_Output : sbit at DIO_P6OUT.B1;`
`var PS2_Data_Direction : sbit; sfr; external;`	Direction of the PS/2 Data pin.	`var PS2_Data_Direction : sbit at DIO_P6DIR.B0;`
`var PS2_Clock_Direction : sbit; sfr; external;`	Direction of the PS/2 Clock pin.	`var PS2_Clock_Direction : sbit at DIO_P6DIR.B1;`

STM32

The following variables must be defined in all projects using PS/2 Library:	Description :	Example :
`var PS2_Data_Input : sbit; sfr; external;`	PS/2 Data Input line.	`var PS2_Data_Input : sbit at GPIOD_IDR.B0;`
`var PS2_Clock_Input : sbit; sfr; external;`	PS/2 Clock Input line.	`var PS2_Clock_Input : sbit at GPIOD_IDR.B1;`
`var PS2_Clock_Output : sbit; sfr; external;`	PS/2 Clock Output line.	`var PS2_Clock_Output : sbit at GPIOD_ODR.B1;`

CEC1x02

The following variables must be defined in all projects using PS/2 Library:	Description :	Example :
`var PS2_Data_Input : sbit; sfr; external;`	PS/2 Data Input line.	`var PS2_Data_Input : sbit at GPIO_INPUT_PIN_001_bit;`
`var PS2_Clock_Input : sbit; sfr; external;`	PS/2 Clock Input line.	`var PS2_Clock_Input : sbit at GPIO_INPUT_PIN_002_bit;`
`var PS2_Clock_Output : sbit; sfr; external;`	PS/2 Clock Output line.	`var PS2_Clock_Output : sbit at GPIO_OUTPUT_PIN_002_bit;`

Library Routines

Ps2_Config
Ps2_Key_Read

Ps2_Config

Prototype	procedure Ps2_Config();
Description	Initializes the MCU for work with the PS/2 keyboard.
Parameters	None.
Returns	Nothing.
Requires	External dependencies of the library from the top of the page must be defined before using this function.
Example	Stellaris // PS2 pinout definition var PS2_Data : sbit at GPIO_PORTD_DATA0_bit; PS2_Clock : sbit at GPIO_PORTD_DATA1_bit; PS2_Data_Direction : sbit at GPIO_PORTD_DIR0_bit; PS2_Clock_Direction : sbit at GPIO_PORTD_DIR1_bit; // End of PS2 pinout definition// Init PS/2 Keyboard MSP432 // PS2 pinout definition var PS2_Data : sbit at DIO_P6OUT.B0; PS2_Clock_Input : sbit at DIO_P6IN.B1; PS2_Clock_Output : sbit at DIO_P6OUT.B1; PS2_Data_Direction : sbit at DIO_P6DIR.B0; PS2_Clock_Direction : sbit at DIO_P6DIR.B1; // End of PS2 pinout definition// Init PS/2 Keyboard STM32 var PS2_Data_Input : sbit at GPIOD_IDR.B0; PS2_Clock_Input : sbit at GPIOD_IDR.B1; PS2_Clock_Output : sbit at GPIOD_ODR.B1; ... Ps2_Config(); // Init PS/2 Keyboard CEC1x02 var PS2_Data_Input : sbit at GPIO_INPUT_PIN_001_bit; PS2_Clock_Input : sbit at GPIO_INPUT_PIN_001_bit; PS2_Clock_Output : sbit at GPIO_OUTPUT_PIN_002_bit; ... Ps2_Config(); // Init PS/2 Keyboard
Notes	None.

Ps2_Key_Read

Prototype	function Ps2_Key_Read(var value : byte; var special : byte; var pressed : byte) : word;
Description	The function retrieves information on key pressed.
Parameters	`value:` holds the value of the key pressed. For characters, numerals, punctuation marks, and space `value` will store the appropriate ASCII code. Routine “recognizes” the function of `Shift` and `Caps Lock`, and behaves appropriately. For special function keys see Special Function Keys Table. `special:` is a flag for special function keys (`F1`, `Enter`, `Esc`, etc). If key pressed is one of these, `special` will be set to 1, otherwise 0. `pressed:` is set to 1 if the key is pressed, and 0 if it is released.
Returns	`1` if reading of a key from the keyboard was successful `0` if no key was pressed
Requires	PS/2 keyboard needs to be initialized. See Ps2_Config routine.
Example	var value, special, pressed : word; ... // Press Enter to continue: repeat { if (Ps2_Key_Read(value, special, pressed)) then if ((value = 13) and (special = 1)) then break; until (0=1);
Notes	None.

Special Function Keys

Key	Value returned
F1	1
F2	2
F3	3
F4	4
F5	5
F6	6
F7	7
F8	8
F9	9
F10	10
F11	11
F12	12
Enter	13
Page Up	14
Page Down	15
Backspace	16
Insert	17
Delete	18
Windows	19
Ctrl	20
Shift	21
Alt	22
Print Screen	23
Pause	24
Caps Lock	25
End	26
Home	27
Scroll Lock	28
Num Lock	29
Left Arrow	30
Right Arrow	31
Up Arrow	32
Down Arrow	33
Escape	34
Tab	35