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Commit | Line | Data |
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9c15f366 L |
1 | ; Serial interface using the ATmega8/88 USART. |
2 | ; This is part of the Z80-CP/M emulator written by Sprite_tm. | |
3 | ; | |
4 | ; Copyright (C) 2010 Leo C. | |
5 | ; | |
6 | ; This file is part of avrcpm. | |
7 | ; | |
8 | ; avrcpm is free software: you can redistribute it and/or modify it | |
9 | ; under the terms of the GNU General Public License as published by | |
10 | ; the Free Software Foundation, either version 3 of the License, or | |
11 | ; (at your option) any later version. | |
12 | ; | |
13 | ; avrcpm is distributed in the hope that it will be useful, | |
14 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | ; GNU General Public License for more details. | |
17 | ; | |
18 | ; You should have received a copy of the GNU General Public License | |
19 | ; along with avrcpm. If not, see <http://www.gnu.org/licenses/>. | |
20 | ; | |
21 | ; $Id$ | |
22 | ; | |
23 | ||
24 | #define SSER_BIT_TC (F_CPU+BAUD/2) / BAUD | |
25 | ||
26 | #define RXBUFMASK RXBUFSIZE-1 | |
27 | #define TXBUFMASK TXBUFSIZE-1 | |
28 | ||
29 | .dseg | |
30 | ||
31 | srx_state: | |
32 | .byte 1 | |
33 | srx_char_to: | |
34 | .byte 1 | |
35 | srx_dr: | |
36 | .byte 1 | |
37 | ;srx_lastedge: | |
38 | ; .byte 2 | |
39 | stx_bitcount: | |
40 | .byte 1 | |
41 | stx_dr: | |
42 | .byte 1 | |
43 | rxcount: | |
44 | .byte 1 | |
45 | rxidx_w: | |
46 | .byte 1 | |
47 | rxidx_r: | |
48 | .byte 1 | |
49 | txcount: | |
50 | .byte 1 | |
51 | txidx_w: | |
52 | .byte 1 | |
53 | txidx_r: | |
54 | .byte 1 | |
55 | rxfifo: | |
56 | .byte RXBUFSIZE | |
57 | txfifo: | |
58 | .byte TXBUFSIZE | |
59 | ||
60 | ||
61 | .cseg | |
62 | ||
63 | ; Init | |
64 | uart_init: | |
65 | ||
66 | ; - Init clock/timer system and serial port | |
67 | ||
68 | ; Init timer 1 as | |
69 | ; - Soft UART TX (OC1A/OCR1A). | |
70 | ; - Soft UART RX (ICP1/ICR1). | |
71 | ; - 1ms System timer is already configured at this point. | |
72 | ||
73 | ldi temp,(1<<COM1A1)|(1<<COM1A0) ;OC1A high on compare match (UART TX) | |
74 | outm8 TCCR1A,temp | |
75 | ||
76 | ldi temp,(1<<ICF1) ;clear pending int | |
77 | out TIFR1,temp | |
78 | inm8 temp,TIMSK1 | |
79 | ori temp,(1<<ICIE1) ;Enable input capture int. (UART RX) | |
80 | outm8 TIMSK1,temp | |
81 | ret | |
82 | ||
83 | ;------------------------------------------------------------------ | |
84 | ||
85 | .cseg | |
9c15f366 | 86 | |
4675c141 L |
87 | ; Timer/Counter1 Input Capture interrupt |
88 | ||
89 | INTERRUPT ICP1addr | |
9c15f366 L |
90 | |
91 | push temp | |
92 | in temp,sreg | |
93 | push temp | |
94 | push zh | |
95 | push zl | |
96 | inm8 zl,ICR1L | |
97 | inm8 zh,ICR1H | |
98 | push temp2 | |
99 | ldi temp2,(1<<ICES1) | |
100 | inm8 temp,TCCR1B | |
101 | eor temp,temp2 ;toggle edge | |
102 | outm8 TCCR1B,temp | |
103 | ldi temp,(1<<ICF1) ;clear pending int | |
104 | out TIFR1,temp | |
105 | ||
106 | #if 0 | |
107 | lds temp,srx_state | |
108 | subi temp,-'0' | |
109 | rcall uartputc | |
110 | lds temp,srx_dr | |
111 | rcall printhex | |
112 | #endif | |
113 | lds temp,srx_state | |
114 | cpi temp,0 | |
115 | brne srxi_S1 | |
116 | ||
117 | ; State 0: Wait for start bit | |
118 | ||
119 | ; sts srx_lastedge,zl ;save beginning of start bit | |
120 | ; sts srx_lastedge+1,zh | |
121 | movw srx_lastedgel,zl | |
fa9059af | 122 | sts srx_dr,_0 |
9c15f366 L |
123 | ldi temp,1 |
124 | sts srx_state,temp | |
125 | ldi temp,2 | |
126 | sts srx_char_to,temp | |
127 | sbis P_RXD-2,RXD ;RXD still low? | |
128 | rjmp srxi_end2 | |
129 | ldi zl,(1<<ICNC1)|(1<<CS10) ;next edge is falling edge | |
130 | outm8 TCCR1B,zl | |
131 | ldi zh,(1<<ICF1) ;clear pending int | |
132 | out TIFR1,zh | |
133 | sts srx_state,_0 | |
134 | sts srx_char_to,_0 | |
135 | rjmp srxi_end2 | |
136 | ||
137 | srxi_S1: | |
138 | cpi temp,1 | |
139 | brne srxi_S2 | |
140 | ||
141 | ; State 1: Check start bit (and collect 0-bits) | |
142 | ||
143 | ; lds temp,srx_lastedge | |
144 | ; lds temp2,srx_lastedge+1 | |
145 | ; sts srx_lastedge,zl | |
146 | ; sts srx_lastedge+1,zh | |
147 | ||
148 | movw temp,srx_lastedgel | |
149 | movw srx_lastedgel,zl | |
150 | ||
151 | sub zl,temp | |
152 | sbc zh,temp2 | |
153 | subi zl,low ((SSER_BIT_TC+1)/2) | |
154 | sbci zh,high((SSER_BIT_TC+1)/2) | |
155 | brcs srxi_sberr | |
156 | ||
157 | ; mov temp,zh | |
158 | ; rcall printhex | |
159 | ; mov temp,zl | |
160 | ; rcall printhex | |
161 | ||
162 | ldi temp,0x80 | |
163 | srxi_1l: | |
164 | subi zl,low(SSER_BIT_TC) | |
165 | sbci zh,high(SSER_BIT_TC) | |
166 | brcs srxi_1be | |
167 | lsr temp | |
168 | brcc srxi_1l | |
fa9059af L |
169 | |
170 | subi zl,low(SSER_BIT_TC) ; stop bit? | |
171 | sbci zh,high(SSER_BIT_TC) | |
172 | brcc srxi_1fe | |
173 | rjmp srxi_complete0 ; ok, x00 (^@) received | |
174 | srxi_1fe: | |
175 | sts srx_char_to,_0 ; no stop bit --> framing error --> break | |
176 | sts srx_state,_0 | |
177 | sbr intstat,(1<<i_break) | |
178 | rjmp srxi_end2 | |
179 | ||
9c15f366 L |
180 | srxi_1be: |
181 | sts srx_dr,temp | |
182 | ldi temp,2 | |
183 | sts srx_state,temp | |
184 | rjmp srxi_end2 | |
185 | ||
186 | srxi_sberr: | |
187 | ldi temp,(1<<ICNC1)|(1<<CS10) ;next edge is falling edge | |
188 | outm8 TCCR1B,temp | |
189 | ldi temp,(1<<ICF1) ;clear pending int | |
190 | out TIFR1,temp | |
191 | sts srx_state,_0 ;next state | |
192 | #if 1 | |
193 | ldi temp,'?' | |
194 | rcall uartputc | |
195 | subi zl,low (-(SSER_BIT_TC+1)/2) | |
196 | sbci zh,high(-(SSER_BIT_TC+1)/2) | |
197 | mov temp,zh | |
198 | rcall printhex | |
199 | mov temp,zl | |
200 | rcall printhex | |
201 | #endif | |
202 | rjmp srxi_end2 | |
203 | ||
204 | srxi_S2: | |
205 | cpi temp,2 | |
206 | brne srxi_S3 | |
207 | ||
208 | ; State 2: collect 1-bits | |
209 | ||
210 | ; lds temp,srx_lastedge | |
211 | ; lds temp2,srx_lastedge+1 | |
212 | ; sts srx_lastedge,zl | |
213 | ; sts srx_lastedge+1,zh | |
214 | ||
215 | movw temp,srx_lastedgel | |
216 | movw srx_lastedgel,zl | |
217 | ||
218 | sub zl,temp | |
219 | sbc zh,temp2 | |
220 | subi zl,low ((SSER_BIT_TC+1)/2) | |
221 | sbci zh,high((SSER_BIT_TC+1)/2) | |
222 | ||
223 | lds temp,srx_dr | |
224 | srxi_2l: | |
225 | sec ;one more 1 bit | |
226 | ror temp | |
227 | brcs srxi_complete1 ;8 bits recieved | |
228 | subi zl,low(SSER_BIT_TC) | |
229 | sbci zh,high(SSER_BIT_TC) | |
230 | brcc srxi_2l | |
231 | ||
232 | sts srx_dr,temp | |
233 | ldi temp,3 | |
234 | sts srx_state,temp | |
235 | rjmp srxi_end2 | |
236 | ||
237 | srxi_complete1: | |
238 | ldi temp2,1 ;We are in start bit now. | |
239 | sts srx_state,temp2 | |
240 | ldi temp2,2 | |
241 | sts srx_char_to,temp2 | |
242 | rjmp srxi_complete | |
243 | ||
244 | srxi_S3: | |
245 | cpi temp,3 | |
246 | brne srxi_S4 | |
247 | ||
248 | ; State 3: collect 0-bits | |
249 | ||
250 | ; lds temp,srx_lastedge | |
251 | ; lds temp2,srx_lastedge+1 | |
252 | ; sts srx_lastedge,zl | |
253 | ; sts srx_lastedge+1,zh | |
254 | ||
255 | movw temp,srx_lastedgel | |
256 | movw srx_lastedgel,zl | |
257 | ||
258 | sub zl,temp | |
259 | sbc zh,temp2 | |
260 | subi zl,low ((SSER_BIT_TC+1)/2) | |
261 | sbci zh,high((SSER_BIT_TC+1)/2) | |
262 | ||
263 | lds temp,srx_dr | |
264 | srxi_3l: | |
265 | ;one more 0 bit | |
266 | lsr temp | |
267 | brcs srxi_complete0 ;8 bits recieved | |
268 | subi zl,low(SSER_BIT_TC) | |
269 | sbci zh,high(SSER_BIT_TC) | |
270 | brcc srxi_3l | |
271 | ||
272 | sts srx_dr,temp | |
273 | ldi temp,2 | |
274 | sts srx_state,temp | |
275 | rjmp srxi_end2 | |
276 | ||
277 | srxi_S4: | |
278 | ldi zl,(1<<ICNC1)|(1<<CS10) ;next edge is falling edge | |
279 | outm8 TCCR1B,zl | |
280 | ldi zl,(1<<ICF1) ;clear pending int | |
281 | sts srx_state,_0 ;next state | |
282 | rjmp srxi_end2 | |
283 | ||
284 | srxi_complete0: | |
285 | sts srx_char_to,_0 ;clear timeout | |
286 | sts srx_state,_0 ;next state | |
287 | srxi_complete: | |
288 | #if 0 | |
289 | ldi zl,(1<<ICNC1)|(1<<CS10) ;next edge is falling edge | |
290 | outm8 TCCR1B,zl | |
291 | ldi zl,(1<<ICF1) ;clear pending int | |
292 | out TIFR1,zl | |
293 | #endif | |
294 | ||
295 | ; Save received character in a circular buffer. Do nothing if buffer overflows. | |
296 | ||
297 | lds zh,rxcount ;if rxcount < RXBUFSIZE | |
298 | cpi zh,RXBUFSIZE ; (room for at least 1 char?) | |
299 | brsh srxi_ov ; | |
300 | inc zh ; | |
301 | sts rxcount,zh ; rxcount++ | |
302 | ||
303 | ldi zl,low(rxfifo) ; | |
304 | lds zh,rxidx_w ; | |
305 | add zl,zh ; | |
306 | inc zh ; | |
307 | andi zh,RXBUFMASK ; | |
308 | sts rxidx_w,zh ; rxidx_w = ++rxidx_w % RXBUFSIZE | |
309 | ldi zh,high(rxfifo) ; | |
310 | brcc PC+2 ; | |
311 | inc zh ; | |
312 | st z,temp ; rxfifo[rxidx_w] = char | |
313 | srxi_ov: ;endif | |
314 | ||
315 | srxi_end2: | |
316 | pop temp2 | |
317 | srxi_end: | |
318 | pop zl | |
319 | pop zh | |
320 | pop temp | |
321 | out sreg,temp | |
322 | pop temp | |
323 | reti | |
324 | ||
325 | ||
326 | ;---------------------------------------------------------------------- | |
327 | ||
328 | .cseg | |
9c15f366 | 329 | |
4675c141 L |
330 | ; Timer/Counter1 Compare Match A interrupt |
331 | ||
332 | INTERRUPT OC1Aaddr | |
9c15f366 L |
333 | |
334 | push temp | |
335 | in temp,sreg | |
336 | push temp | |
337 | push zh | |
338 | ||
339 | inm8 temp,OCR1AL | |
340 | inm8 zh,OCR1AH | |
341 | subi temp,low(-SSER_BIT_TC) | |
342 | sbci zh,high(-SSER_BIT_TC) | |
343 | outm8 OCR1AH,zh | |
344 | outm8 OCR1AL,temp | |
345 | lds temp,stx_bitcount | |
346 | tst temp | |
347 | breq stxi_nxtchar | |
348 | ||
349 | dec temp | |
350 | sts stx_bitcount,temp | |
351 | ldi zh,9 ;Start bit? | |
352 | cp temp,zh | |
353 | ldi zh,(1<<COM1A1) | |
354 | breq stxi_0 | |
355 | lds temp,stx_dr | |
356 | sbrs temp,0 | |
357 | ldi zh,(1<<COM1A1)|(1<<COM1A0) | |
358 | lsr temp | |
359 | sts stx_dr,temp | |
360 | stxi_0: | |
361 | outm8 TCCR1A,zh | |
362 | pop zh | |
363 | pop temp | |
364 | out sreg,temp | |
365 | pop temp | |
366 | reti | |
367 | ||
368 | ; more characters? | |
369 | stxi_nxtchar: | |
370 | lds temp,txcount ;if txcount != 0 | |
371 | tst temp ; | |
372 | breq stxi_dis | |
373 | ; get next char | |
374 | push zl | |
375 | dec temp ; | |
376 | sts txcount,temp ; --txcount | |
377 | ldi zl,low(txfifo) ; | |
378 | ldi zh,high(txfifo) ; | |
379 | lds temp,txidx_r ; | |
380 | add zl,temp ; | |
381 | brcc PC+2 ; | |
382 | inc zh ; | |
383 | inc temp ; | |
384 | andi temp,TXBUFMASK ; | |
385 | sts txidx_r,temp ; | |
386 | ld temp,z | |
387 | com temp | |
388 | sts stx_dr,temp | |
389 | ldi temp,10 | |
390 | sts stx_bitcount,temp | |
391 | pop zl | |
392 | pop zh | |
393 | pop temp | |
394 | out sreg,temp | |
395 | pop temp | |
396 | reti | |
397 | ||
398 | ; disable transmitter | |
399 | stxi_dis: | |
400 | ldi temp,(1<<COM1A1)|(1<<COM1A0) | |
401 | outm8 TCCR1A,temp | |
402 | inm8 temp,TIMSK1 | |
403 | andi temp,~(1<<OCIE1A) | |
404 | outm8 TIMSK1,temp | |
405 | pop zh | |
406 | pop temp | |
407 | out sreg,temp | |
408 | pop temp | |
409 | reti | |
410 | ;------------------------------------------------------------------ | |
411 | ||
412 | srx_to: | |
413 | #if 0 | |
414 | ldi zl,(1<<ICNC1)|(1<<CS10) ;next edge is falling edge | |
415 | outm8 TCCR1B,zl | |
416 | ldi zl,(1<<ICF1) ;clear pending int | |
417 | out TIFR1,zl | |
418 | #endif | |
fa9059af | 419 | sts srx_state,_0 ;next state |
9c15f366 L |
420 | push temp |
421 | ||
422 | #if 0 | |
423 | ldi temp,'|' | |
424 | rcall uartputc | |
425 | #endif | |
fa9059af L |
426 | lds temp,srx_dr ;only 0 if timeout after leading edge of start bit. |
427 | tst temp | |
428 | brne srxto_store | |
429 | sbr intstat,(1<<i_break) | |
430 | rjmp srxto_ov | |
431 | ||
432 | srxto_store: | |
9c15f366 L |
433 | mov zl,temp |
434 | com zl | |
435 | andi zl,0x80 | |
436 | srxto_l: | |
437 | lsr temp | |
438 | or temp,zl | |
439 | brcc srxto_l | |
440 | ||
441 | ; Save received character in a circular buffer. Do nothing if buffer overflows. | |
442 | ||
443 | lds zh,rxcount ;if rxcount < RXBUFSIZE | |
444 | cpi zh,RXBUFSIZE ; (room for at least 1 char?) | |
445 | brsh srxto_ov ; | |
446 | inc zh ; | |
447 | sts rxcount,zh ; rxcount++ | |
448 | ||
449 | ldi zl,low(rxfifo) ; | |
450 | lds zh,rxidx_w ; | |
451 | add zl,zh ; | |
452 | inc zh ; | |
453 | andi zh,RXBUFMASK ; | |
454 | sts rxidx_w,zh ; rxidx_w = ++rxidx_w % RXBUFSIZE | |
455 | ldi zh,high(rxfifo) ; | |
456 | brcc PC+2 ; | |
457 | inc zh ; | |
458 | st z,temp ; rxfifo[rxidx_w] = char | |
459 | srxto_ov: ;endif | |
9c15f366 L |
460 | |
461 | pop temp | |
462 | ret | |
463 | ||
464 | ||
465 | ;Fetches a char from the buffer to temp. If none available, waits till one is. | |
466 | ||
467 | uartgetc: | |
468 | lds temp,rxcount ;Number of characters in buffer | |
469 | tst temp | |
470 | breq uartgetc ;Wait for char | |
471 | ||
472 | push zh | |
473 | push zl | |
474 | ldi zl,low(rxfifo) | |
475 | ldi zh,high(rxfifo) | |
476 | lds temp,rxidx_r | |
477 | add zl,temp | |
478 | brcc PC+2 | |
479 | inc zh | |
480 | inc temp | |
481 | andi temp,RXBUFMASK | |
482 | sts rxidx_r,temp | |
483 | cli | |
484 | lds temp,rxcount | |
485 | dec temp | |
486 | sts rxcount,temp | |
487 | sei | |
488 | ld temp,z ;don't forget to get the char | |
489 | pop zl | |
490 | pop zh | |
491 | ret | |
492 | ||
493 | ;Sends a char from temp to the soft uart. | |
494 | ||
495 | uartputc: | |
496 | push zh | |
497 | push zl | |
498 | in zl,sreg | |
499 | push zl | |
500 | push temp | |
501 | sputc_l: | |
502 | lds temp,txcount ;do { | |
503 | cpi temp,TXBUFSIZE ; | |
504 | brsh sputc_l ;} while (txcount >= TXBUFSIZE) | |
505 | ||
506 | ldi zl,low(txfifo) ; | |
507 | ldi zh,high(txfifo) ; | |
508 | lds temp,txidx_w ; | |
509 | add zl,temp ; | |
510 | brcc PC+2 ; | |
511 | inc zh ; | |
512 | inc temp ; | |
513 | andi temp,TXBUFMASK ; | |
514 | sts txidx_w,temp ; txidx_w = ++txidx_w % TXBUFSIZE | |
515 | pop temp ; | |
516 | st z,temp ; txfifo[txidx_w] = char | |
517 | cli | |
518 | lds zh,txcount | |
519 | inc zh | |
520 | sts txcount,zh | |
521 | dec zh | |
522 | brne sputc_e | |
523 | ; Enable transmitter | |
524 | inm8 zh,TIMSK1 | |
525 | ori zh,(1<<OCIE1A) | |
526 | outm8 TIMSK1,zh | |
527 | sputc_e: | |
528 | pop zl | |
529 | out sreg,zl | |
530 | pop zl | |
531 | pop zh | |
532 | ret | |
533 | ||
534 | ||
535 | ; Wait, till tx buffer is empty. | |
536 | ||
537 | uart_wait_empty: | |
538 | push temp | |
539 | uwe_loop: | |
540 | lds temp,txcount | |
541 | tst temp | |
542 | brne uwe_loop | |
543 | pop temp | |
544 | ret | |
545 | ||
546 | ||
547 | ; vim:set ts=8 noet nowrap | |
548 |