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/*
Copyright 2010 , 2011 , 2012 , 2013 Jun WAKO < wakojun @ gmail . com >
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 busywait version
*/
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# include <stdbool.h>
# include <util/delay.h>
# include "ps2.h"
# include "debug.h"
# define WAIT(stat, us, err) do { \
if ( ! wait_ # # stat ( us ) ) { \
ps2_error = err ; \
goto ERROR ; \
} \
} while ( 0 )
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uint8_t ps2_error = PS2_ERR_NONE ;
void ps2_host_init ( void )
{
// POR(150-2000ms) plus BAT(300-500ms) may take 2.5sec([3]p.20)
_delay_ms ( 2500 ) ;
inhibit ( ) ;
}
uint8_t ps2_host_send ( uint8_t data )
{
bool parity = true ;
ps2_error = PS2_ERR_NONE ;
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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 ( ) ;
clock_hi ( ) ;
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WAIT ( clock_lo , 10000 , 10 ) ; // 10ms [5]p.50
/* Data bit */
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for ( uint8_t i = 0 ; i < 8 ; i + + ) {
_delay_us ( 15 ) ;
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 ) ;
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 ) ;
data_hi ( ) ;
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/* Ack */
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WAIT ( data_lo , 50 , 6 ) ;
WAIT ( clock_lo , 50 , 7 ) ;
/* wait for idle state */
WAIT ( clock_hi , 50 , 8 ) ;
WAIT ( data_hi , 50 , 9 ) ;
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inhibit ( ) ;
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return ps2_host_recv_response ( ) ;
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ERROR :
inhibit ( ) ;
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return 0 ;
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}
/* receive data when host want else inhibit communication */
uint8_t ps2_host_recv_response ( void )
{
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// Command may take 25ms/20ms at most([5]p.46, [3]p.21)
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// 250 * 100us(wait for start bit in ps2_host_recv)
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uint8_t data = 0 ;
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uint8_t try = 250 ;
do {
data = ps2_host_recv ( ) ;
} while ( try - - & & ps2_error ) ;
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return data ;
}
/* called after start bit comes */
uint8_t ps2_host_recv ( void )
{
uint8_t data = 0 ;
bool parity = true ;
ps2_error = PS2_ERR_NONE ;
/* release lines(idle state) */
idle ( ) ;
/* start bit [1] */
WAIT ( clock_lo , 100 , 1 ) ; // TODO: this is enough?
WAIT ( data_lo , 1 , 2 ) ;
WAIT ( clock_hi , 50 , 3 ) ;
/* data [2-9] */
for ( uint8_t i = 0 ; i < 8 ; i + + ) {
WAIT ( clock_lo , 50 , 4 ) ;
if ( data_in ( ) ) {
parity = ! parity ;
data | = ( 1 < < i ) ;
}
WAIT ( clock_hi , 50 , 5 ) ;
}
/* parity [10] */
WAIT ( clock_lo , 50 , 6 ) ;
if ( data_in ( ) ! = parity ) {
ps2_error = PS2_ERR_PARITY ;
goto ERROR ;
}
WAIT ( clock_hi , 50 , 7 ) ;
/* stop bit [11] */
WAIT ( clock_lo , 50 , 8 ) ;
WAIT ( data_hi , 1 , 9 ) ;
WAIT ( clock_hi , 50 , 10 ) ;
inhibit ( ) ;
return data ;
ERROR :
if ( ps2_error > PS2_ERR_STARTBIT3 ) {
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xprintf ( " x%02X \n " , ps2_error ) ;
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}
inhibit ( ) ;
return 0 ;
}
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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 ) ;
}