2 Copyright 2010,2011,2012,2013,2019 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.
10 Redistribution and use in source and binary forms, with or without
11 modification, are permitted provided that the following conditions are met:
13 * Redistributions of source code must retain the above copyright
14 notice, this list of conditions and the following disclaimer.
16 * Redistributions in binary form must reproduce the above copyright
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
22 contributors may be used to endorse or promote products derived
23 from this software without specific prior written permission.
25 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
26 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
29 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35 POSSIBILITY OF SUCH DAMAGE.
39 * IBM PC keyboard protocol
43 #include <avr/interrupt.h>
44 #include <util/atomic.h>
51 #define WAIT(stat, us, err) do { \
52 if (!wait_##stat(us)) { \
59 volatile uint16_t ibmpc_isr_debug = 0;
60 volatile uint8_t ibmpc_protocol = IBMPC_PROTOCOL_NO;
61 volatile uint8_t ibmpc_error = IBMPC_ERR_NONE;
63 /* 2-byte buffer for data received from keyboard
69 * where ss, tt and ee are 0x00-0xFE. 0xFF means empty or no data in buffer.
71 static volatile uint16_t recv_data = 0xFFFF;
72 /* internal state of receiving data */
73 static volatile uint16_t isr_state = 0x8000;
74 static uint8_t timer_start = 0;
76 void ibmpc_host_init(void)
78 // initialize reset pin to HiZ
85 void ibmpc_host_enable(void)
91 void ibmpc_host_disable(void)
97 int16_t ibmpc_host_send(uint8_t data)
100 ibmpc_error = IBMPC_ERR_NONE;
102 dprintf("w%02X ", data);
106 /* terminate a transmission if we have */
108 wait_us(100); // 100us [4]p.13, [5]p.50
110 /* 'Request to Send' and Start bit */
113 WAIT(clock_lo, 10000, 1); // 10ms [5]p.50
116 for (uint8_t i = 0; i < 8; i++) {
124 WAIT(clock_hi, 50, 2);
125 WAIT(clock_lo, 50, 3);
130 if (parity) { data_hi(); } else { data_lo(); }
131 WAIT(clock_hi, 50, 4);
132 WAIT(clock_lo, 50, 5);
139 WAIT(data_lo, 50, 6);
140 WAIT(clock_lo, 50, 7);
142 /* wait for idle state */
143 WAIT(clock_hi, 50, 8);
144 WAIT(data_hi, 50, 9);
146 // clear buffer to get response correctly
148 ibmpc_host_isr_clear();
152 return ibmpc_host_recv_response();
154 ibmpc_error |= IBMPC_ERR_SEND;
161 * Receive data from keyboard
163 int16_t ibmpc_host_recv(void)
168 ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
171 // remove data from buffer:
172 // FFFF(empty) -> FFFF
173 // FFss(one data) -> FFFF
174 // sstt(two data) -> FFtt
175 // eeFF(errror) -> FFFF
176 recv_data = data | (((data&0xFF00) == 0xFF00) ? 0x00FF : 0xFF00);
179 if ((data&0x00FF) == 0x00FF) {
183 // 0xFF(Overrun/Error) from keyboard
197 dprintf("e%02X ", data>>8);
201 if ((data | 0x00FF) != 0xFFFF) {
203 dprintf("b:%04X ", data);
211 //dprintf("i%04X ", ibmpc_isr_debug); ibmpc_isr_debug = 0;
212 dprintf("r%02X ", ret);
216 int16_t ibmpc_host_recv_response(void)
218 // Command may take 25ms/20ms at most([5]p.46, [3]p.21)
221 while (retry-- && (data = ibmpc_host_recv()) == -1) {
227 void ibmpc_host_isr_clear(void)
236 #define LO8(w) (*((uint8_t *)&(w)))
237 #define HI8(w) (*(((uint8_t *)&(w))+1))
238 // NOTE: With this ISR data line can be read within 2us after clock falling edge.
239 // To read data line early as possible:
240 // write naked ISR with asembly code to read the line and call C func to do other job?
244 dbit = IBMPC_DATA_PIN&(1<<IBMPC_DATA_BIT);
248 // use only the least byte of millisecond timer
249 asm("lds %0, %1" : "=r" (t) : "p" (&timer_count));
250 //t = (uint8_t)timer_count; // compiler uses four registers instead of one
251 if (isr_state == 0x8000) {
254 // should not take more than 1ms
255 if (timer_start != t && (uint8_t)(timer_start + 1) != t) {
256 ibmpc_isr_debug = isr_state;
257 ibmpc_error = IBMPC_ERR_TIMEOUT;
260 // timeout error recovery - start receiving new data
261 // it seems to work somehow but may not under unstable situation
263 //isr_state = 0x8000;
267 isr_state = isr_state>>1;
268 if (dbit) isr_state |= 0x8000;
270 // isr_state: state of receiving data from keyboard
272 // This should be initialized with 0x8000 before receiving data and
273 // the MSB '*1' works as marker to discrimitate between protocols.
274 // It stores sampled bit at MSB after right shift on each clock falling edge.
276 // XT protocol has two variants of signaling; XT_IBM and XT_Clone.
277 // XT_IBM uses two start bits 0 and 1 while XT_Clone uses just start bit 1.
278 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol
280 // 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
281 // -----------------------------------------------------
282 // *1 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0 Initial state(0x8000)
284 // x x x x x x x x | 0 0 0 0 0 0 0 0 midway(0-7 bits received)
285 // x x x x x x x x | *1 0 0 0 0 0 0 0 midway(8 bits received)
286 // b6 b5 b4 b3 b2 b1 b0 1 | 0 *1 0 0 0 0 0 0 XT_IBM-midway ^1
287 // b7 b6 b5 b4 b3 b2 b1 b0 | 0 *1 0 0 0 0 0 0 AT-midway ^1
288 // b7 b6 b5 b4 b3 b2 b1 b0 | 1 *1 0 0 0 0 0 0 XT_Clone-done ^3
289 // b6 b5 b4 b3 b2 b1 b0 1 | 1 *1 0 0 0 0 0 0 XT_IBM-error ^3
290 // pr b7 b6 b5 b4 b3 b2 b1 | 0 0 *1 0 0 0 0 0 AT-midway[b0=0]
291 // b7 b6 b5 b4 b3 b2 b1 b0 | 1 0 *1 0 0 0 0 0 XT_IBM-done ^2
292 // pr b7 b6 b5 b4 b3 b2 b1 | 1 0 *1 0 0 0 0 0 AT-midway[b0=1] ^2
293 // b7 b6 b5 b4 b3 b2 b1 b0 | 1 1 *1 0 0 0 0 0 XT_IBM-error-done
294 // x x x x x x x x | x 1 1 0 0 0 0 0 illegal
295 // st pr b7 b6 b5 b4 b3 b2 | b1 b0 0 *1 0 0 0 0 AT-done
296 // x x x x x x x x | x x 1 *1 0 0 0 0 illegal
297 // all other states than above illegal
299 // ^1: AT and XT_IBM takes same state.
300 // ^2: AT and XT_IBM takes same state in case that AT b0 is 1,
301 // we have to check AT stop bit to discriminate between the two protocol.
302 switch (isr_state & 0xFF) {
305 case 0b01000000: // ^1
310 case 0b11000000: // ^3
313 // wait for rising and falling edge of b7 of XT_IBM
314 while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
315 while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
318 // XT_IBM-error: read start(0) as 1
322 ibmpc_isr_debug = isr_state;
323 isr_state = isr_state>>8;
324 ibmpc_protocol = IBMPC_PROTOCOL_XT_CLONE;
331 ibmpc_isr_debug = isr_state;
332 isr_state = isr_state>>8;
333 ibmpc_protocol = IBMPC_PROTOCOL_XT_ERROR;
336 case 0b10100000: // ^2
339 // wait for rising and falling edge of AT stop bit to discriminate between XT and AT
340 while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
341 while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
344 // found stop bit: AT-midway - process the stop bit in next ISR
347 // no stop bit: XT_IBM-done
348 ibmpc_isr_debug = isr_state;
349 isr_state = isr_state>>8;
350 ibmpc_protocol = IBMPC_PROTOCOL_XT_IBM;
360 // DO NOT check stop bit. Zenith Z-150(AT) asserts stop bit as low for no reason.
361 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#zenith-z-150-beige
362 // TODO: parity check?
363 ibmpc_isr_debug = isr_state;
364 isr_state = isr_state>>6;
365 ibmpc_protocol = IBMPC_PROTOCOL_AT;
373 default: // xxxx_oooo(any 1 in low nibble)
375 ibmpc_isr_debug = isr_state;
376 ibmpc_error = IBMPC_ERR_ILLEGAL;
383 recv_data = (ibmpc_error<<8) | 0x00FF;
386 if ((isr_state & 0x00FF) == 0x00FF) {
387 // receive error code 0xFF
388 ibmpc_error = IBMPC_ERR_FF;
391 if (HI8(recv_data) != 0xFF && LO8(recv_data) != 0xFF) {
393 ibmpc_error = IBMPC_ERR_FULL;
397 recv_data = recv_data<<8;
398 recv_data |= isr_state & 0xFF;
400 // clear for next data
406 /* send LED state to keyboard */
407 void ibmpc_host_set_led(uint8_t led)
409 if (0xFA == ibmpc_host_send(0xED)) {
410 ibmpc_host_send(led);