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 */
114 WAIT(clock_lo, 10000, 1); // 10ms [5]p.50
117 for (uint8_t i = 0; i < 8; i++) {
125 WAIT(clock_hi, 50, 2);
126 WAIT(clock_lo, 50, 3);
131 if (parity) { data_hi(); } else { data_lo(); }
132 WAIT(clock_hi, 50, 4);
133 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);
147 // clear buffer to get response correctly
149 ibmpc_host_isr_clear();
153 return ibmpc_host_recv_response();
155 ibmpc_error |= IBMPC_ERR_SEND;
162 * Receive data from keyboard
164 int16_t ibmpc_host_recv(void)
169 ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
172 // remove data from buffer:
173 // FFFF(empty) -> FFFF
174 // FFss(one data) -> FFFF
175 // sstt(two data) -> FFtt
176 // eeFF(errror) -> FFFF
177 recv_data = data | (((data&0xFF00) == 0xFF00) ? 0x00FF : 0xFF00);
180 if ((data&0x00FF) == 0x00FF) {
184 // 0xFF(Overrun/Error) from keyboard
198 dprintf("e%02X ", data>>8);
202 if ((data | 0x00FF) != 0xFFFF) {
204 dprintf("b:%04X ", data);
212 //dprintf("i%04X ", ibmpc_isr_debug); ibmpc_isr_debug = 0;
213 dprintf("r%02X ", ret);
217 int16_t ibmpc_host_recv_response(void)
219 // Command may take 25ms/20ms at most([5]p.46, [3]p.21)
222 while (retry-- && (data = ibmpc_host_recv()) == -1) {
228 void ibmpc_host_isr_clear(void)
237 #define LO8(w) (*((uint8_t *)&(w)))
238 #define HI8(w) (*(((uint8_t *)&(w))+1))
239 // NOTE: With this ISR data line can be read within 2us after clock falling edge.
240 // To read data line early as possible:
241 // write naked ISR with asembly code to read the line and call C func to do other job?
245 dbit = IBMPC_DATA_PIN&(1<<IBMPC_DATA_BIT);
249 // use only the least byte of millisecond timer
250 asm("lds %0, %1" : "=r" (t) : "p" (&timer_count));
251 //t = (uint8_t)timer_count; // compiler uses four registers instead of one
252 if (isr_state == 0x8000) {
255 // should not take more than 1ms
256 if (timer_start != t && (uint8_t)(timer_start + 1) != t) {
257 ibmpc_isr_debug = isr_state;
258 ibmpc_error = IBMPC_ERR_TIMEOUT;
261 // timeout error recovery - start receiving new data
262 // it seems to work somehow but may not under unstable situation
264 //isr_state = 0x8000;
268 isr_state = isr_state>>1;
269 if (dbit) isr_state |= 0x8000;
271 // isr_state: state of receiving data from keyboard
273 // This should be initialized with 0x8000 before receiving data and
274 // the MSB '*1' works as marker to discrimitate between protocols.
275 // It stores sampled bit at MSB after right shift on each clock falling edge.
277 // XT protocol has two variants of signaling; XT_IBM and XT_Clone.
278 // XT_IBM uses two start bits 0 and 1 while XT_Clone uses just start bit 1.
279 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-XT-Keyboard-Protocol
281 // 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
282 // -----------------------------------------------------
283 // *1 0 0 0 0 0 0 0 | 0 0 0 0 0 0 0 0 Initial state(0x8000)
285 // x x x x x x x x | 0 0 0 0 0 0 0 0 midway(0-7 bits received)
286 // x x x x x x x x | *1 0 0 0 0 0 0 0 midway(8 bits received)
287 // b6 b5 b4 b3 b2 b1 b0 1 | 0 *1 0 0 0 0 0 0 XT_IBM-midway ^1
288 // b7 b6 b5 b4 b3 b2 b1 b0 | 0 *1 0 0 0 0 0 0 AT-midway ^1
289 // b7 b6 b5 b4 b3 b2 b1 b0 | 1 *1 0 0 0 0 0 0 XT_Clone-done ^3
290 // b6 b5 b4 b3 b2 b1 b0 1 | 1 *1 0 0 0 0 0 0 XT_IBM-error ^3
291 // pr b7 b6 b5 b4 b3 b2 b1 | 0 0 *1 0 0 0 0 0 AT-midway[b0=0]
292 // b7 b6 b5 b4 b3 b2 b1 b0 | 1 0 *1 0 0 0 0 0 XT_IBM-done ^2
293 // pr b7 b6 b5 b4 b3 b2 b1 | 1 0 *1 0 0 0 0 0 AT-midway[b0=1] ^2
294 // b7 b6 b5 b4 b3 b2 b1 b0 | 1 1 *1 0 0 0 0 0 XT_IBM-error-done
295 // x x x x x x x x | x 1 1 0 0 0 0 0 illegal
296 // st pr b7 b6 b5 b4 b3 b2 | b1 b0 0 *1 0 0 0 0 AT-done
297 // x x x x x x x x | x x 1 *1 0 0 0 0 illegal
298 // all other states than above illegal
300 // ^1: AT and XT_IBM takes same state.
301 // ^2: AT and XT_IBM takes same state in case that AT b0 is 1,
302 // we have to check AT stop bit to discriminate between the two protocol.
303 switch (isr_state & 0xFF) {
306 case 0b01000000: // ^1
311 case 0b11000000: // ^3
314 // wait for rising and falling edge of b7 of XT_IBM
315 while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
316 while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
319 // XT_IBM-error: read start(0) as 1
323 ibmpc_isr_debug = isr_state;
324 isr_state = isr_state>>8;
325 ibmpc_protocol = IBMPC_PROTOCOL_XT_CLONE;
332 ibmpc_isr_debug = isr_state;
333 isr_state = isr_state>>8;
334 ibmpc_protocol = IBMPC_PROTOCOL_XT_ERROR;
337 case 0b10100000: // ^2
340 // wait for rising and falling edge of AT stop bit to discriminate between XT and AT
341 while (!(IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT)) && us) { wait_us(1); us--; }
342 while ( IBMPC_CLOCK_PIN&(1<<IBMPC_CLOCK_BIT) && us) { wait_us(1); us--; }
345 // found stop bit: AT-midway - process the stop bit in next ISR
348 // no stop bit: XT_IBM-done
349 ibmpc_isr_debug = isr_state;
350 isr_state = isr_state>>8;
351 ibmpc_protocol = IBMPC_PROTOCOL_XT_IBM;
361 // DO NOT check stop bit. Zenith Z-150(AT) asserts stop bit as low for no reason.
362 // https://github.com/tmk/tmk_keyboard/wiki/IBM-PC-AT-Keyboard-Protocol#zenith-z-150-beige
363 // TODO: parity check?
364 ibmpc_isr_debug = isr_state;
365 isr_state = isr_state>>6;
366 ibmpc_protocol = IBMPC_PROTOCOL_AT;
374 default: // xxxx_oooo(any 1 in low nibble)
376 ibmpc_isr_debug = isr_state;
377 ibmpc_error = IBMPC_ERR_ILLEGAL;
384 recv_data = (ibmpc_error<<8) | 0x00FF;
387 if ((isr_state & 0x00FF) == 0x00FF) {
388 // receive error code 0xFF
389 ibmpc_error = IBMPC_ERR_FF;
392 if (HI8(recv_data) != 0xFF && LO8(recv_data) != 0xFF) {
394 ibmpc_error = IBMPC_ERR_FULL;
398 recv_data = recv_data<<8;
399 recv_data |= isr_state & 0xFF;
401 // clear for next data
407 /* send LED state to keyboard */
408 void ibmpc_host_set_led(uint8_t led)
410 if (0xFA == ibmpc_host_send(0xED)) {
411 ibmpc_host_send(led);