]>
Commit | Line | Data |
---|---|---|
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 | |
86 | srxint: | |
87 | .org ICP1addr ; Timer/Counter1 Input Capture | |
88 | rjmp srxint ; Soft UART: RX | |
89 | ||
90 | .org srxint | |
91 | ||
92 | push temp | |
93 | in temp,sreg | |
94 | push temp | |
95 | push zh | |
96 | push zl | |
97 | inm8 zl,ICR1L | |
98 | inm8 zh,ICR1H | |
99 | push temp2 | |
100 | ldi temp2,(1<<ICES1) | |
101 | inm8 temp,TCCR1B | |
102 | eor temp,temp2 ;toggle edge | |
103 | outm8 TCCR1B,temp | |
104 | ldi temp,(1<<ICF1) ;clear pending int | |
105 | out TIFR1,temp | |
106 | ||
107 | #if 0 | |
108 | lds temp,srx_state | |
109 | subi temp,-'0' | |
110 | rcall uartputc | |
111 | lds temp,srx_dr | |
112 | rcall printhex | |
113 | #endif | |
114 | lds temp,srx_state | |
115 | cpi temp,0 | |
116 | brne srxi_S1 | |
117 | ||
118 | ; State 0: Wait for start bit | |
119 | ||
120 | ; sts srx_lastedge,zl ;save beginning of start bit | |
121 | ; sts srx_lastedge+1,zh | |
122 | movw srx_lastedgel,zl | |
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 | |
169 | rjmp srxi_complete | |
170 | srxi_1be: | |
171 | sts srx_dr,temp | |
172 | ldi temp,2 | |
173 | sts srx_state,temp | |
174 | rjmp srxi_end2 | |
175 | ||
176 | srxi_sberr: | |
177 | ldi temp,(1<<ICNC1)|(1<<CS10) ;next edge is falling edge | |
178 | outm8 TCCR1B,temp | |
179 | ldi temp,(1<<ICF1) ;clear pending int | |
180 | out TIFR1,temp | |
181 | sts srx_state,_0 ;next state | |
182 | #if 1 | |
183 | ldi temp,'?' | |
184 | rcall uartputc | |
185 | subi zl,low (-(SSER_BIT_TC+1)/2) | |
186 | sbci zh,high(-(SSER_BIT_TC+1)/2) | |
187 | mov temp,zh | |
188 | rcall printhex | |
189 | mov temp,zl | |
190 | rcall printhex | |
191 | #endif | |
192 | rjmp srxi_end2 | |
193 | ||
194 | srxi_S2: | |
195 | cpi temp,2 | |
196 | brne srxi_S3 | |
197 | ||
198 | ; State 2: collect 1-bits | |
199 | ||
200 | ; lds temp,srx_lastedge | |
201 | ; lds temp2,srx_lastedge+1 | |
202 | ; sts srx_lastedge,zl | |
203 | ; sts srx_lastedge+1,zh | |
204 | ||
205 | movw temp,srx_lastedgel | |
206 | movw srx_lastedgel,zl | |
207 | ||
208 | sub zl,temp | |
209 | sbc zh,temp2 | |
210 | subi zl,low ((SSER_BIT_TC+1)/2) | |
211 | sbci zh,high((SSER_BIT_TC+1)/2) | |
212 | ||
213 | lds temp,srx_dr | |
214 | srxi_2l: | |
215 | sec ;one more 1 bit | |
216 | ror temp | |
217 | brcs srxi_complete1 ;8 bits recieved | |
218 | subi zl,low(SSER_BIT_TC) | |
219 | sbci zh,high(SSER_BIT_TC) | |
220 | brcc srxi_2l | |
221 | ||
222 | sts srx_dr,temp | |
223 | ldi temp,3 | |
224 | sts srx_state,temp | |
225 | rjmp srxi_end2 | |
226 | ||
227 | srxi_complete1: | |
228 | ldi temp2,1 ;We are in start bit now. | |
229 | sts srx_state,temp2 | |
230 | ldi temp2,2 | |
231 | sts srx_char_to,temp2 | |
232 | rjmp srxi_complete | |
233 | ||
234 | srxi_S3: | |
235 | cpi temp,3 | |
236 | brne srxi_S4 | |
237 | ||
238 | ; State 3: collect 0-bits | |
239 | ||
240 | ; lds temp,srx_lastedge | |
241 | ; lds temp2,srx_lastedge+1 | |
242 | ; sts srx_lastedge,zl | |
243 | ; sts srx_lastedge+1,zh | |
244 | ||
245 | movw temp,srx_lastedgel | |
246 | movw srx_lastedgel,zl | |
247 | ||
248 | sub zl,temp | |
249 | sbc zh,temp2 | |
250 | subi zl,low ((SSER_BIT_TC+1)/2) | |
251 | sbci zh,high((SSER_BIT_TC+1)/2) | |
252 | ||
253 | lds temp,srx_dr | |
254 | srxi_3l: | |
255 | ;one more 0 bit | |
256 | lsr temp | |
257 | brcs srxi_complete0 ;8 bits recieved | |
258 | subi zl,low(SSER_BIT_TC) | |
259 | sbci zh,high(SSER_BIT_TC) | |
260 | brcc srxi_3l | |
261 | ||
262 | sts srx_dr,temp | |
263 | ldi temp,2 | |
264 | sts srx_state,temp | |
265 | rjmp srxi_end2 | |
266 | ||
267 | srxi_S4: | |
268 | ldi zl,(1<<ICNC1)|(1<<CS10) ;next edge is falling edge | |
269 | outm8 TCCR1B,zl | |
270 | ldi zl,(1<<ICF1) ;clear pending int | |
271 | sts srx_state,_0 ;next state | |
272 | rjmp srxi_end2 | |
273 | ||
274 | srxi_complete0: | |
275 | sts srx_char_to,_0 ;clear timeout | |
276 | sts srx_state,_0 ;next state | |
277 | srxi_complete: | |
278 | #if 0 | |
279 | ldi zl,(1<<ICNC1)|(1<<CS10) ;next edge is falling edge | |
280 | outm8 TCCR1B,zl | |
281 | ldi zl,(1<<ICF1) ;clear pending int | |
282 | out TIFR1,zl | |
283 | #endif | |
284 | ||
285 | ; Save received character in a circular buffer. Do nothing if buffer overflows. | |
286 | ||
287 | lds zh,rxcount ;if rxcount < RXBUFSIZE | |
288 | cpi zh,RXBUFSIZE ; (room for at least 1 char?) | |
289 | brsh srxi_ov ; | |
290 | inc zh ; | |
291 | sts rxcount,zh ; rxcount++ | |
292 | ||
293 | ldi zl,low(rxfifo) ; | |
294 | lds zh,rxidx_w ; | |
295 | add zl,zh ; | |
296 | inc zh ; | |
297 | andi zh,RXBUFMASK ; | |
298 | sts rxidx_w,zh ; rxidx_w = ++rxidx_w % RXBUFSIZE | |
299 | ldi zh,high(rxfifo) ; | |
300 | brcc PC+2 ; | |
301 | inc zh ; | |
302 | st z,temp ; rxfifo[rxidx_w] = char | |
303 | srxi_ov: ;endif | |
304 | ||
305 | srxi_end2: | |
306 | pop temp2 | |
307 | srxi_end: | |
308 | pop zl | |
309 | pop zh | |
310 | pop temp | |
311 | out sreg,temp | |
312 | pop temp | |
313 | reti | |
314 | ||
315 | ||
316 | ;---------------------------------------------------------------------- | |
317 | ||
318 | .cseg | |
319 | stxint: | |
320 | .org OC1Aaddr ; Timer/Counter1 Compare Match A | |
321 | rjmp stxint ; Soft UART: TX | |
322 | ||
323 | .org stxint | |
324 | ||
325 | push temp | |
326 | in temp,sreg | |
327 | push temp | |
328 | push zh | |
329 | ||
330 | inm8 temp,OCR1AL | |
331 | inm8 zh,OCR1AH | |
332 | subi temp,low(-SSER_BIT_TC) | |
333 | sbci zh,high(-SSER_BIT_TC) | |
334 | outm8 OCR1AH,zh | |
335 | outm8 OCR1AL,temp | |
336 | lds temp,stx_bitcount | |
337 | tst temp | |
338 | breq stxi_nxtchar | |
339 | ||
340 | dec temp | |
341 | sts stx_bitcount,temp | |
342 | ldi zh,9 ;Start bit? | |
343 | cp temp,zh | |
344 | ldi zh,(1<<COM1A1) | |
345 | breq stxi_0 | |
346 | lds temp,stx_dr | |
347 | sbrs temp,0 | |
348 | ldi zh,(1<<COM1A1)|(1<<COM1A0) | |
349 | lsr temp | |
350 | sts stx_dr,temp | |
351 | stxi_0: | |
352 | outm8 TCCR1A,zh | |
353 | pop zh | |
354 | pop temp | |
355 | out sreg,temp | |
356 | pop temp | |
357 | reti | |
358 | ||
359 | ; more characters? | |
360 | stxi_nxtchar: | |
361 | lds temp,txcount ;if txcount != 0 | |
362 | tst temp ; | |
363 | breq stxi_dis | |
364 | ; get next char | |
365 | push zl | |
366 | dec temp ; | |
367 | sts txcount,temp ; --txcount | |
368 | ldi zl,low(txfifo) ; | |
369 | ldi zh,high(txfifo) ; | |
370 | lds temp,txidx_r ; | |
371 | add zl,temp ; | |
372 | brcc PC+2 ; | |
373 | inc zh ; | |
374 | inc temp ; | |
375 | andi temp,TXBUFMASK ; | |
376 | sts txidx_r,temp ; | |
377 | ld temp,z | |
378 | com temp | |
379 | sts stx_dr,temp | |
380 | ldi temp,10 | |
381 | sts stx_bitcount,temp | |
382 | pop zl | |
383 | pop zh | |
384 | pop temp | |
385 | out sreg,temp | |
386 | pop temp | |
387 | reti | |
388 | ||
389 | ; disable transmitter | |
390 | stxi_dis: | |
391 | ldi temp,(1<<COM1A1)|(1<<COM1A0) | |
392 | outm8 TCCR1A,temp | |
393 | inm8 temp,TIMSK1 | |
394 | andi temp,~(1<<OCIE1A) | |
395 | outm8 TIMSK1,temp | |
396 | pop zh | |
397 | pop temp | |
398 | out sreg,temp | |
399 | pop temp | |
400 | reti | |
401 | ;------------------------------------------------------------------ | |
402 | ||
403 | srx_to: | |
404 | #if 0 | |
405 | ldi zl,(1<<ICNC1)|(1<<CS10) ;next edge is falling edge | |
406 | outm8 TCCR1B,zl | |
407 | ldi zl,(1<<ICF1) ;clear pending int | |
408 | out TIFR1,zl | |
409 | #endif | |
410 | push temp | |
411 | ||
412 | #if 0 | |
413 | ldi temp,'|' | |
414 | rcall uartputc | |
415 | #endif | |
416 | lds temp,srx_dr | |
417 | mov zl,temp | |
418 | com zl | |
419 | andi zl,0x80 | |
420 | srxto_l: | |
421 | lsr temp | |
422 | or temp,zl | |
423 | brcc srxto_l | |
424 | ||
425 | ; Save received character in a circular buffer. Do nothing if buffer overflows. | |
426 | ||
427 | lds zh,rxcount ;if rxcount < RXBUFSIZE | |
428 | cpi zh,RXBUFSIZE ; (room for at least 1 char?) | |
429 | brsh srxto_ov ; | |
430 | inc zh ; | |
431 | sts rxcount,zh ; rxcount++ | |
432 | ||
433 | ldi zl,low(rxfifo) ; | |
434 | lds zh,rxidx_w ; | |
435 | add zl,zh ; | |
436 | inc zh ; | |
437 | andi zh,RXBUFMASK ; | |
438 | sts rxidx_w,zh ; rxidx_w = ++rxidx_w % RXBUFSIZE | |
439 | ldi zh,high(rxfifo) ; | |
440 | brcc PC+2 ; | |
441 | inc zh ; | |
442 | st z,temp ; rxfifo[rxidx_w] = char | |
443 | srxto_ov: ;endif | |
444 | sts srx_state,_0 ;next state | |
445 | ||
446 | pop temp | |
447 | ret | |
448 | ||
449 | ||
450 | ;Fetches a char from the buffer to temp. If none available, waits till one is. | |
451 | ||
452 | uartgetc: | |
453 | lds temp,rxcount ;Number of characters in buffer | |
454 | tst temp | |
455 | breq uartgetc ;Wait for char | |
456 | ||
457 | push zh | |
458 | push zl | |
459 | ldi zl,low(rxfifo) | |
460 | ldi zh,high(rxfifo) | |
461 | lds temp,rxidx_r | |
462 | add zl,temp | |
463 | brcc PC+2 | |
464 | inc zh | |
465 | inc temp | |
466 | andi temp,RXBUFMASK | |
467 | sts rxidx_r,temp | |
468 | cli | |
469 | lds temp,rxcount | |
470 | dec temp | |
471 | sts rxcount,temp | |
472 | sei | |
473 | ld temp,z ;don't forget to get the char | |
474 | pop zl | |
475 | pop zh | |
476 | ret | |
477 | ||
478 | ;Sends a char from temp to the soft uart. | |
479 | ||
480 | uartputc: | |
481 | push zh | |
482 | push zl | |
483 | in zl,sreg | |
484 | push zl | |
485 | push temp | |
486 | sputc_l: | |
487 | lds temp,txcount ;do { | |
488 | cpi temp,TXBUFSIZE ; | |
489 | brsh sputc_l ;} while (txcount >= TXBUFSIZE) | |
490 | ||
491 | ldi zl,low(txfifo) ; | |
492 | ldi zh,high(txfifo) ; | |
493 | lds temp,txidx_w ; | |
494 | add zl,temp ; | |
495 | brcc PC+2 ; | |
496 | inc zh ; | |
497 | inc temp ; | |
498 | andi temp,TXBUFMASK ; | |
499 | sts txidx_w,temp ; txidx_w = ++txidx_w % TXBUFSIZE | |
500 | pop temp ; | |
501 | st z,temp ; txfifo[txidx_w] = char | |
502 | cli | |
503 | lds zh,txcount | |
504 | inc zh | |
505 | sts txcount,zh | |
506 | dec zh | |
507 | brne sputc_e | |
508 | ; Enable transmitter | |
509 | inm8 zh,TIMSK1 | |
510 | ori zh,(1<<OCIE1A) | |
511 | outm8 TIMSK1,zh | |
512 | sputc_e: | |
513 | pop zl | |
514 | out sreg,zl | |
515 | pop zl | |
516 | pop zh | |
517 | ret | |
518 | ||
519 | ||
520 | ; Wait, till tx buffer is empty. | |
521 | ||
522 | uart_wait_empty: | |
523 | push temp | |
524 | uwe_loop: | |
525 | lds temp,txcount | |
526 | tst temp | |
527 | brne uwe_loop | |
528 | pop temp | |
529 | ret | |
530 | ||
531 | ||
532 | ; vim:set ts=8 noet nowrap | |
533 |