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V1.0.2 Initial Public release
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‎PS2KeyRaw.cpp‎

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/* Version V1.0.2
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PS2KeyRaw.cpp - PS2KeyRaw library
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Copyright (c) 2007 Free Software Foundation. All right reserved.
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Written by Paul Carpenter, PC Services <[email protected]>
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Stripped down version of PS2Keyboard to get every key code byte from a PS2
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Keyboard for testing purposes. Enables capture of all bytes see example.
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IMPORTANT WARNING
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If using a DUE or similar board with 3V3 I/O you MUST put a level translator
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like a Texas Instruments TXS0102 or FET circuit as the signals are
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Bi-directional (signals transmitted from both ends on same wire).
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Failure to do so may damage your Arduino Due or similar board.
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Test History
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September 2014 Uno and Mega 2560 September 2014 using Arduino V1.6.0
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January 2016 Uno, Mega 2560 and Due using Arduino 1.6.7 and Due Board
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Manager V1.6.6
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Created September 2014 based, on PS2Keyboard which was
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Written by Christian Weichel <[email protected]>
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** Mostly rewritten Paul Stoffregen <[email protected]> 2010, 2011
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** Modified for use beginning with Arduino 13 by L. Abraham Smith, <[email protected]> *
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** Modified for easy interrupt pin assignment on method begin(datapin,irq_pin). Cuningan <[email protected]> **
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V1.0.1 Modified September 2014 Paul Carpenter for easier state machines and parity checks
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V1.0.2 Modified January 2016 to improve interrupt assignment with new Arduino macros
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "PS2KeyRaw.h"
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/* Private variable definition */
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#define BUFFER_SIZE 16
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volatile uint8_t buffer[ BUFFER_SIZE ];
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volatile uint8_t head, tail;
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uint8_t PS2_DataPin;
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/* Private function declarations */
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uint8_t get_scan_code( );
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// The ISR for the external interrupt
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// To receive 11 bits start, 8 data, ODD parity, stop
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// Interrupt every falling incoming clock edge from keyboard
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void ps2interrupt( void )
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{
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static uint8_t bitcount = 0; // Main state variable and bit count
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static uint8_t incoming;
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static uint8_t parity;
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static uint32_t prev_ms = 0;
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uint32_t now_ms;
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uint8_t val;
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val = digitalRead( PS2_DataPin );
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now_ms = millis();
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if( now_ms - prev_ms > 250 )
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bitcount = 0;
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prev_ms = now_ms;
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bitcount++; // Now point to next bit
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switch( bitcount )
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{
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case 1: // Start bit
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incoming = 0;
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parity = 0;
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break;
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case 2:
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case 3:
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case 4:
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case 5:
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case 6:
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case 7:
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case 8:
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case 9: // Data bits
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parity += val; // another one received ?
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incoming >>= 1; // right shift one place for next bit
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incoming |= ( val ) ? 0x80 : 0; // or in MSbit
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break;
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case 10: // Parity check
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parity &= 1; // Get LSB if 1 = odd number of 1's so parity should be 0
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if( parity == val ) // Both same parity error
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parity = 0xFD; // To ensure at next bit count clear and discard
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break;
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case 11: // Stop bit
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if( parity >= 0xFD ) // had parity error
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{
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// Should send resend byte command here currently discard
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}
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else // Good so save byte in buffer
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{
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val = head + 1;
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if( val >= BUFFER_SIZE )
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val = 0;
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if( val != tail )
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{
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buffer[ val ] = incoming;
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head = val;
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}
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}
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// fall through to default
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default: // in case of weird error and end of byte reception re-sync
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bitcount = 0;
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}
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}
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uint8_t get_scan_code(void)
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{
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uint8_t i;
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i = tail;
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if( i == head ) // check for empty buffer
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return 0;
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i++;
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if( i >= BUFFER_SIZE )
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i = 0;
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tail = i;
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return buffer[ i ];
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}
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int8_t PS2KeyRaw::available()
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{
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int8_t i;
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if( tail == head )
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return false;
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i = tail - head;
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if( i < 0 )
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i += BUFFER_SIZE;
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return i;
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}
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int PS2KeyRaw::read()
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{
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uint8_t result;
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result = 0;
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if( ( result = available() ) )
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result = get_scan_code();
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if( result == 0 )
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result = -1;
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return result;
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}
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PS2KeyRaw::PS2KeyRaw() {
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// nothing to do here, begin() does it all
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}
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void PS2KeyRaw::begin( uint8_t data_pin, uint8_t irq_pin )
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{
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PS2_DataPin = data_pin;
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// initialize the pins
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#ifdef INPUT_PULLUP
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pinMode(irq_pin, INPUT_PULLUP);
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pinMode(data_pin, INPUT_PULLUP);
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#else
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pinMode(irq_pin, INPUT);
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digitalWrite(irq_pin, HIGH);
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pinMode(data_pin, INPUT);
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digitalWrite(data_pin, HIGH);
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#endif
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// Initialise buffer indexes
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head = 0;
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tail = 0;
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// Setup interrupt handler
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attachInterrupt( digitalPinToInterrupt( irq_pin ), ps2interrupt, FALLING );
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}
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‎PS2KeyRaw.h‎

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/* Version V1.0.2
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PS2KeyRaw.h - PS2KeyRaw library
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Copyright (c) 2007 Free Software Foundation. All right reserved.
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Written by Paul Carpenter, PC Services <[email protected]>
5+
6+
Stripped down version of PS2Keyboard to get every key code byte from a PS2
7+
Keyboard for testing purposes. Enables capture of all bytes see examples.
8+
9+
IMPORTANT WARNING
10+
11+
If using a DUE or similar board with 3V3 I/O you MUST put a level translator
12+
like a Texas Instruments TXS0102 or FET circuit as the signals are
13+
Bi-directional (signals transmitted from both ends on same wire).
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15+
Failure to do so may damage your Arduino Due or similar board.
16+
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Test History
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September 2014 Uno and Mega 2560 September 2014 using Arduino V1.6.0
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January 2016 Uno, Mega 2560 and Due using Arduino 1.6.7 and Due Board
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Manager V1.6.6
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The circuit:
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* KBD Clock (PS2 pin 1) to an interrupt pin on Arduino ( this example pin 3 )
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* KBD Data (PS2 pin 5) to a data pin ( this example pin 4 )
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* +5V from Arduino to PS2 pin 4
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* GND from Arduino to PS2 pin 3
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The connector to mate with PS2 keyboard is a 6 pin Female Mini-Din connector
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PS2 Pins to signal
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1 KBD Data
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3 GND
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4 +5V
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5 KBD Clock
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Keyboard has 5V and GND connected see plenty of examples and
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photos around on Arduino site and other sites about the PS2 Connector.
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Interrupts
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Clock pin from PS2 keyboard MUST be connected to an interrupt
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pin, these vary with the different types of Arduino
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Valid irq pins:
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Arduino Uno: 2, 3
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Arduino Due: All pins, except 13 (LED)
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Arduino Mega: 2, 3, 18, 19, 20, 21
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Teensy 2.0: All pins, except 13 (LED)
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Teensy 2.0: 5, 6, 7, 8
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Teensy 1.0: 0, 1, 2, 3, 4, 6, 7, 16
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Teensy++ 2.0: 0, 1, 2, 3, 18, 19, 36, 37
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Teensy++ 1.0: 0, 1, 2, 3, 18, 19, 36, 37
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Sanguino: 2, 10, 11
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Created September 2014 based, on PS2Keyboard which was
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Written by Christian Weichel <[email protected]>
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** Mostly rewritten Paul Stoffregen <[email protected]> 2010, 2011
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** Modified for use beginning with Arduino 13 by L. Abraham Smith, <[email protected]> *
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** Modified for easy interrupt pin assignment on method begin(datapin,irq_pin). Cuningan <[email protected]> **
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V1.0.1 Modified September 2014 Paul Carpenter for easier state machines and parity checks
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V1.0.2 Modified January 2016 to improve interrupt assignment with new Arduino macros
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef PS2KeyRaw_h
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#define PS2KeyRaw_h
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#include "Arduino.h" // for attachInterrupt, FALLING
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/**
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* Purpose: Provides an easy access to PS2 keyboards
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* Author: Christian Weichel
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*/
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class PS2KeyRaw {
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public:
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/**
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* This constructor does basically nothing. Please call the begin(int,int)
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* method before using any other method of this class.
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*/
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PS2KeyRaw();
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/**
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* Starts the keyboard "service" by registering the external interrupt.
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* setting the pin modes correctly and driving those needed to high.
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* The best place to call this method is in the setup routine.
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*/
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static void begin( uint8_t dataPin, uint8_t irq_pin );
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/**
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* Returns number of bytes available.
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*/
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static int8_t available();
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/**
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* Returns the char last read from the keyboard.
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* If there is no char available, -1 is returned.
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*/
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static int read();
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};
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#endif

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