2 Copyright 2010,2011,2012,2013 Jun WAKO <wakojun@gmail.com>
4 This software is licensed with a Modified BSD License.
5 All of this is supposed to be Free Software, Open Source, DFSG-free,
6 GPL-compatible, and OK to use in both free and proprietary applications.
7 Additions and corrections to this file are welcome.
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14 notice, this list of conditions and the following disclaimer.
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17 notice, this list of conditions and the following disclaimer in
18 the documentation and/or other materials provided with the
21 * Neither the name of the copyright holders nor the names of
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23 from this software without specific prior written permission.
25 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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35 POSSIBILITY OF SUCH DAMAGE.
39 Primitive PS/2 Library for AVR
40 ==============================
41 Host side is only supported now.
42 Synchronous USART is used to receive data by hardware process
43 rather than interrupt. During V-USB interrupt runs, CLOCK interrupt
44 cannot interpose. In the result it is prone to lost CLOCK edge.
49 High state is asserted by internal pull-up.
50 If you have a signaling problem, you may need to have
51 external pull-up resisters on CLOCK and DATA line.
56 http://www.computer-engineering.org/ps2protocol/
57 http://www.mcamafia.de/pdf/ibm_hitrc07.pdf
61 #include <avr/interrupt.h>
62 #include <util/delay.h>
67 #define WAIT(stat, us, err) do { \
68 if (!wait_##stat(us)) { \
75 uint8_t ps2_error = PS2_ERR_NONE;
78 static inline void clock_lo(void);
79 static inline void clock_hi(void);
80 static inline bool clock_in(void);
81 static inline void data_lo(void);
82 static inline void data_hi(void);
83 static inline bool data_in(void);
84 static inline uint16_t wait_clock_lo(uint16_t us);
85 static inline uint16_t wait_clock_hi(uint16_t us);
86 static inline uint16_t wait_data_lo(uint16_t us);
87 static inline uint16_t wait_data_hi(uint16_t us);
88 static inline void idle(void);
89 static inline void inhibit(void);
90 static inline uint8_t pbuf_dequeue(void);
91 static inline void pbuf_enqueue(uint8_t data);
92 static inline bool pbuf_has_data(void);
93 static inline void pbuf_clear(void);
96 void ps2_host_init(void)
100 PS2_USART_RX_INT_ON();
103 uint8_t ps2_host_send(uint8_t data)
107 ps2_error = PS2_ERR_NONE;
111 /* terminate a transmission if we have */
118 WAIT(clock_lo, 15000, 1);
120 for (uint8_t i = 0; i < 8; i++) {
128 WAIT(clock_hi, 50, 2);
129 WAIT(clock_lo, 50, 3);
133 if (parity) { data_hi(); } else { data_lo(); }
134 WAIT(clock_hi, 50, 4);
135 WAIT(clock_lo, 50, 5);
140 WAIT(data_lo, 50, 6);
141 WAIT(clock_lo, 50, 7);
143 /* wait for idle state */
144 WAIT(clock_hi, 50, 8);
145 WAIT(data_hi, 50, 9);
148 PS2_USART_RX_INT_ON();
149 res = ps2_host_recv_response();
153 PS2_USART_RX_INT_ON();
157 // Do polling data from keyboard to get response to last command.
158 uint8_t ps2_host_recv_response(void)
160 while (!pbuf_has_data()) {
161 _delay_ms(1); // without this delay it seems to fall into deadlock
163 return pbuf_dequeue();
166 uint8_t ps2_host_recv(void)
168 return pbuf_dequeue();
171 ISR(PS2_USART_RX_VECT)
173 uint8_t error = PS2_USART_ERROR;
174 uint8_t data = PS2_USART_RX_DATA;
180 /* send LED state to keyboard */
181 void ps2_host_set_led(uint8_t led)
183 // send 0xED then keyboard keeps waiting for next LED data
184 // and keyboard does not send any scan codes during waiting.
185 // If fail to send LED data keyboard looks like being freezed.
187 while (retry-- && ps2_host_send(PS2_SET_LED) != PS2_ACK)
190 while (retry-- && ps2_host_send(led) != PS2_ACK)
195 /*--------------------------------------------------------------------
197 *------------------------------------------------------------------*/
198 static inline void clock_lo()
200 PS2_CLOCK_PORT &= ~(1<<PS2_CLOCK_BIT);
201 PS2_CLOCK_DDR |= (1<<PS2_CLOCK_BIT);
203 static inline void clock_hi()
205 /* input with pull up */
206 PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT);
207 PS2_CLOCK_PORT |= (1<<PS2_CLOCK_BIT);
209 static inline bool clock_in()
211 PS2_CLOCK_DDR &= ~(1<<PS2_CLOCK_BIT);
212 PS2_CLOCK_PORT |= (1<<PS2_CLOCK_BIT);
214 return PS2_CLOCK_PIN&(1<<PS2_CLOCK_BIT);
216 static inline void data_lo()
218 PS2_DATA_PORT &= ~(1<<PS2_DATA_BIT);
219 PS2_DATA_DDR |= (1<<PS2_DATA_BIT);
221 static inline void data_hi()
223 /* input with pull up */
224 PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT);
225 PS2_DATA_PORT |= (1<<PS2_DATA_BIT);
227 static inline bool data_in()
229 PS2_DATA_DDR &= ~(1<<PS2_DATA_BIT);
230 PS2_DATA_PORT |= (1<<PS2_DATA_BIT);
232 return PS2_DATA_PIN&(1<<PS2_DATA_BIT);
235 static inline uint16_t wait_clock_lo(uint16_t us)
237 while (clock_in() && us) { asm(""); _delay_us(1); us--; }
240 static inline uint16_t wait_clock_hi(uint16_t us)
242 while (!clock_in() && us) { asm(""); _delay_us(1); us--; }
245 static inline uint16_t wait_data_lo(uint16_t us)
247 while (data_in() && us) { asm(""); _delay_us(1); us--; }
250 static inline uint16_t wait_data_hi(uint16_t us)
252 while (!data_in() && us) { asm(""); _delay_us(1); us--; }
256 /* idle state that device can send */
257 static inline void idle(void)
263 /* inhibit device to send */
264 static inline void inhibit(void)
271 /*--------------------------------------------------------------------
272 * Ring buffer to store scan codes from keyboard
273 *------------------------------------------------------------------*/
275 static uint8_t pbuf[PBUF_SIZE];
276 static uint8_t pbuf_head = 0;
277 static uint8_t pbuf_tail = 0;
278 static inline void pbuf_enqueue(uint8_t data)
282 uint8_t next = (pbuf_head + 1) % PBUF_SIZE;
283 if (next != pbuf_tail) {
284 pbuf[pbuf_head] = data;
287 debug("pbuf: full\n");
292 static inline uint8_t pbuf_dequeue(void)
298 if (pbuf_head != pbuf_tail) {
299 val = pbuf[pbuf_tail];
300 pbuf_tail = (pbuf_tail + 1) % PBUF_SIZE;
306 static inline bool pbuf_has_data(void)
310 bool has_data = (pbuf_head != pbuf_tail);
314 static inline void pbuf_clear(void)
318 pbuf_head = pbuf_tail = 0;