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/*
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Copyright 2010 , 2011 , 2012 , 2013 Jun WAKO < wakojun @ gmail . com >
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This software is licensed with a Modified BSD License .
All of this is supposed to be Free Software , Open Source , DFSG - free ,
GPL - compatible , and OK to use in both free and proprietary applications .
Additions and corrections to this file are welcome .
Redistribution and use in source and binary forms , with or without
modification , are permitted provided that the following conditions are met :
* Redistributions of source code must retain the above copyright
notice , this list of conditions and the following disclaimer .
* Redistributions in binary form must reproduce the above copyright
notice , this list of conditions and the following disclaimer in
the documentation and / or other materials provided with the
distribution .
* Neither the name of the copyright holders nor the names of
contributors may be used to endorse or promote products derived
from this software without specific prior written permission .
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS " AS IS "
AND ANY EXPRESS OR IMPLIED WARRANTIES , INCLUDING , BUT NOT LIMITED TO , THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED . IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT , INDIRECT , INCIDENTAL , SPECIAL , EXEMPLARY , OR
CONSEQUENTIAL DAMAGES ( INCLUDING , BUT NOT LIMITED TO , PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES ; LOSS OF USE , DATA , OR PROFITS ; OR BUSINESS
INTERRUPTION ) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY , WHETHER IN
CONTRACT , STRICT LIABILITY , OR TORT ( INCLUDING NEGLIGENCE OR OTHERWISE )
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE , EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE .
*/
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/*
* PS / 2 protocol Pin interrupt version
*/
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# include <stdbool.h>
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# include <avr/interrupt.h>
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# include <util/delay.h>
# include "ps2.h"
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# include "print.h"
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# define WAIT(stat, us, err) do { \
if ( ! wait_ # # stat ( us ) ) { \
ps2_error = err ; \
goto ERROR ; \
} \
} while ( 0 )
uint8_t ps2_error = PS2_ERR_NONE ;
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static inline uint8_t pbuf_dequeue ( void ) ;
static inline void pbuf_enqueue ( uint8_t data ) ;
static inline bool pbuf_has_data ( void ) ;
static inline void pbuf_clear ( void ) ;
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void ps2_host_init ( void )
{
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idle ( ) ;
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PS2_INT_INIT ( ) ;
PS2_INT_ON ( ) ;
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// POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
//_delay_ms(2500);
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}
uint8_t ps2_host_send ( uint8_t data )
{
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bool parity = true ;
ps2_error = PS2_ERR_NONE ;
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PS2_INT_OFF ( ) ;
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/* terminate a transmission if we have */
inhibit ( ) ;
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_delay_us ( 100 ) ; // 100us [4]p.13, [5]p.50
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/* 'Request to Send' and Start bit */
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data_lo ( ) ;
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clock_hi ( ) ;
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WAIT ( clock_lo , 10000 , 10 ) ; // 10ms [5]p.50
/* Data bit[2-9] */
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for ( uint8_t i = 0 ; i < 8 ; i + + ) {
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_delay_us ( 15 ) ;
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if ( data & ( 1 < < i ) ) {
parity = ! parity ;
data_hi ( ) ;
} else {
data_lo ( ) ;
}
WAIT ( clock_hi , 50 , 2 ) ;
WAIT ( clock_lo , 50 , 3 ) ;
}
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/* Parity bit */
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_delay_us ( 15 ) ;
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if ( parity ) { data_hi ( ) ; } else { data_lo ( ) ; }
WAIT ( clock_hi , 50 , 4 ) ;
WAIT ( clock_lo , 50 , 5 ) ;
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/* Stop bit */
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_delay_us ( 15 ) ;
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data_hi ( ) ;
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/* Ack */
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WAIT ( data_lo , 50 , 6 ) ;
WAIT ( clock_lo , 50 , 7 ) ;
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/* wait for idle state */
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WAIT ( clock_hi , 50 , 8 ) ;
WAIT ( data_hi , 50 , 9 ) ;
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idle ( ) ;
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PS2_INT_ON ( ) ;
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return ps2_host_recv_response ( ) ;
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ERROR :
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idle ( ) ;
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PS2_INT_ON ( ) ;
return 0 ;
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}
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uint8_t ps2_host_recv_response ( void )
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{
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// Command may take 25ms/20ms at most([5]p.46, [3]p.21)
uint8_t retry = 25 ;
while ( retry - - & & ! pbuf_has_data ( ) ) {
_delay_ms ( 1 ) ;
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}
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return pbuf_dequeue ( ) ;
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}
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/* get data received by interrupt */
uint8_t ps2_host_recv ( void )
{
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if ( pbuf_has_data ( ) ) {
ps2_error = PS2_ERR_NONE ;
return pbuf_dequeue ( ) ;
} else {
ps2_error = PS2_ERR_NODATA ;
return 0 ;
}
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}
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ISR ( PS2_INT_VECT )
{
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static enum {
INIT ,
START ,
BIT0 , BIT1 , BIT2 , BIT3 , BIT4 , BIT5 , BIT6 , BIT7 ,
PARITY ,
STOP ,
} state = INIT ;
static uint8_t data = 0 ;
static uint8_t parity = 1 ;
// TODO: abort if elapse 100us from previous interrupt
// return unless falling edge
if ( clock_in ( ) ) {
goto RETURN ;
}
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state + + ;
switch ( state ) {
case START :
if ( data_in ( ) )
goto ERROR ;
break ;
case BIT0 :
case BIT1 :
case BIT2 :
case BIT3 :
case BIT4 :
case BIT5 :
case BIT6 :
case BIT7 :
data > > = 1 ;
if ( data_in ( ) ) {
data | = 0x80 ;
parity + + ;
}
break ;
case PARITY :
if ( data_in ( ) ) {
if ( ! ( parity & 0x01 ) )
goto ERROR ;
} else {
if ( parity & 0x01 )
goto ERROR ;
}
break ;
case STOP :
if ( ! data_in ( ) )
goto ERROR ;
pbuf_enqueue ( data ) ;
goto DONE ;
break ;
default :
goto ERROR ;
}
goto RETURN ;
ERROR :
ps2_error = state ;
DONE :
state = INIT ;
data = 0 ;
parity = 1 ;
RETURN :
return ;
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}
/* send LED state to keyboard */
void ps2_host_set_led ( uint8_t led )
{
ps2_host_send ( 0xED ) ;
ps2_host_send ( led ) ;
}
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/*--------------------------------------------------------------------
* Ring buffer to store scan codes from keyboard
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
# define PBUF_SIZE 32
static uint8_t pbuf [ PBUF_SIZE ] ;
static uint8_t pbuf_head = 0 ;
static uint8_t pbuf_tail = 0 ;
static inline void pbuf_enqueue ( uint8_t data )
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{
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uint8_t sreg = SREG ;
cli ( ) ;
uint8_t next = ( pbuf_head + 1 ) % PBUF_SIZE ;
if ( next ! = pbuf_tail ) {
pbuf [ pbuf_head ] = data ;
pbuf_head = next ;
} else {
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print ( " pbuf: full \n " ) ;
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}
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SREG = sreg ;
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}
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static inline uint8_t pbuf_dequeue ( void )
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{
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uint8_t val = 0 ;
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uint8_t sreg = SREG ;
cli ( ) ;
if ( pbuf_head ! = pbuf_tail ) {
val = pbuf [ pbuf_tail ] ;
pbuf_tail = ( pbuf_tail + 1 ) % PBUF_SIZE ;
}
SREG = sreg ;
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return val ;
}
static inline bool pbuf_has_data ( void )
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{
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uint8_t sreg = SREG ;
cli ( ) ;
bool has_data = ( pbuf_head ! = pbuf_tail ) ;
SREG = sreg ;
return has_data ;
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}
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static inline void pbuf_clear ( void )
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{
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uint8_t sreg = SREG ;
cli ( ) ;
pbuf_head = pbuf_tail = 0 ;
SREG = sreg ;
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}
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