diff options
Diffstat (limited to 'ps2.c')
| -rw-r--r-- | ps2.c | 248 |
1 files changed, 248 insertions, 0 deletions
@@ -0,0 +1,248 @@ +/* +Copyright (c) 2010 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. +*/ +#include <stdbool.h> +#include <avr/io.h> +#include <util/delay.h> +#include "ps2.h" +#include "print.h" +#include "debug.h" + + +static inline void clock_lo(void); +static inline void clock_hi(void); +static inline bool clock_in(void); +static inline void data_lo(void); +static inline void data_hi(void); +static inline bool data_in(void); +static inline uint16_t wait_clock_lo(uint16_t us); +static inline uint16_t wait_clock_hi(uint16_t us); +static inline uint16_t wait_data_lo(uint16_t us); +static inline uint16_t wait_data_hi(uint16_t us); + + +/* +Primitive PS/2 Library for AVR +============================== +Host side is only supported now. + + +I/O control +----------- +High state is asserted by input with pull up. + + +PS/2 References +--------------- +http://www.computer-engineering.org/ps2protocol/ +http://www.mcamafia.de/pdf/ibm_hitrc07.pdf +*/ + + +#define WAIT(stat, us, err) do { \ + if (!wait_##stat(us)) { \ + ps2_error = err; \ + goto ERROR; \ + } \ +} while (0) + +#define WAIT_NORETRY(stat, us, err) do { \ + if (!wait_##stat(us)) { \ + ps2_error = err; \ + return 0; \ + } \ +} while (0) + + +uint8_t ps2_error = PS2_ERR_NONE; + + +void ps2_host_init(void) +{ + /* inhibit */ + clock_lo(); + data_hi(); +} + +uint8_t ps2_host_send(uint8_t data) +{ + bool parity = true; + ps2_error = 0; + + /* request to send */ + clock_lo(); + data_lo(); + _delay_us(100); + /* start bit [1] */ + clock_hi(); + WAIT(clock_lo, 15000, 1); + /* data [2-9] */ + for (uint8_t i = 0; i < 8; i++) { + if (data&(1<<i)) { + parity = !parity; + data_hi(); + } else { + data_lo(); + } + WAIT(clock_hi, 50, 2); + WAIT(clock_lo, 50, 3); + } + /* parity [10] */ + if (parity) { data_hi(); } else { data_lo(); } + WAIT(clock_hi, 50, 4); + WAIT(clock_lo, 50, 5); + /* stop bit [11] */ + data_hi(); + /* ack [12] */ + WAIT(data_lo, 50, 6); + WAIT(clock_lo, 50, 7); + WAIT(clock_hi, 50, 8); + WAIT(data_hi, 50, 9); + + /* inhibit device to send */ + clock_lo(); + + return 1; +ERROR: + return 0; +} + +uint8_t ps2_host_recv(void) +{ + uint8_t data = 0; + bool parity = true; + ps2_error = 0; + + /* cancel to sync */ + clock_lo(); + _delay_us(100); + + /* release lines(idle state) */ + clock_hi(); + data_hi(); + + /* start bit [1] */ + WAIT(clock_lo, 20000, 1); + 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 device to send */ + clock_lo(); + + return data; +ERROR: + return 0; +} + + +static inline void clock_lo() +{ + PS2_CLOCK_PORT &= ~(1<<PS2_CLOCK_BIT); + PS2_CLOCK_DDR |= (1<<PS2_CLOCK_BIT); +} +static inline void clock_hi() +{ + /* input with pull up */ + PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT); + PS2_CLOCK_PORT |= (1<<PS2_CLOCK_BIT); +} +static inline bool clock_in() +{ + PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT); + PS2_CLOCK_PORT |= (1<<PS2_CLOCK_BIT); + return PS2_CLOCK_PIN&(1<<PS2_CLOCK_BIT); +} +static inline void data_lo() +{ + PS2_DATA_PORT &= ~(1<<PS2_DATA_BIT); + PS2_DATA_DDR |= (1<<PS2_DATA_BIT); +} +static inline void data_hi() +{ + /* input with pull up */ + PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT); + PS2_DATA_PORT |= (1<<PS2_DATA_BIT); +} +static inline bool data_in() +{ + PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT); + PS2_DATA_PORT |= (1<<PS2_DATA_BIT); + return PS2_DATA_PIN&(1<<PS2_DATA_BIT); +} + +static inline uint16_t wait_clock_lo(uint16_t us) +{ + while (clock_in() && us) { asm(""); _delay_us(1); us--; } + return us; +} +static inline uint16_t wait_clock_hi(uint16_t us) +{ + while (!clock_in() && us) { asm(""); _delay_us(1); us--; } + return us; +} +static inline uint16_t wait_data_lo(uint16_t us) +{ + while (data_in() && us) { asm(""); _delay_us(1); us--; } + return us; +} +static inline uint16_t wait_data_hi(uint16_t us) +{ + while (!data_in() && us) { asm(""); _delay_us(1); us--; } + return us; +} |