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comparison 1wire.c @ 8:f9a085a0ba93

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Change the 1 wire routines to mostly C with assembly delay routines for ease of portability.
author darius
date Mon, 12 Jul 2004 17:50:42 +0930
parents ffeab3c04e83
children eb1faf51968e
comparison
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7:a940431af6f5 8:f9a085a0ba93
1 /* 1 /*
2 * Various 1 wire routines 2 * Various 1 wire routines
3 * Search routine is copied from the Dallas owpd library with mods. 3 * Search routine is copied from the Dallas owpd library with mods.
4 *
5 * $Id$
4 * 6 *
5 * Copyright (c) 2004 7 * Copyright (c) 2004
6 * Daniel O'Connor <darius@dons.net.au>. All rights reserved. 8 * Daniel O'Connor <darius@dons.net.au>. All rights reserved.
7 * 9 *
8 * Redistribution and use in source and binary forms, with or without 10 * Redistribution and use in source and binary forms, with or without
30 #include <stdio.h> 32 #include <stdio.h>
31 #include <avr/io.h> 33 #include <avr/io.h>
32 #include <avr/pgmspace.h> 34 #include <avr/pgmspace.h>
33 35
34 #include "1wire.h" 36 #include "1wire.h"
37 #include "1wire-delay.h"
35 38
36 void uart_putsP(const char *addr); 39 void uart_putsP(const char *addr);
37 void uart_puts(const char *addr); 40 void uart_puts(const char *addr);
38 void uart_getc(); 41 void uart_getc();
39 int uart_putc(char c); 42 int uart_putc(char c);
135 */ 138 */
136 void 139 void
137 OWWriteBit(int bit) { 140 OWWriteBit(int bit) {
138 OWdelay(); 141 OWdelay();
139 if (bit) { 142 if (bit) {
140 asm volatile ( 143 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
141 /* Drive bus low */ 144 OWIREDDR |= _BV(OWIREOUTPIN);
142 "cbi %[out], %[pin]\n\t" 145 DELAY_A;
143 "sbi %[ddr], %[pin]\n\t" 146 OWIREDDR &= ~(_BV(OWIREOUTPIN));
144 /* Delay A (6 usec) */ 147 DELAY_B;
145 "ldi r21, 1\n\t"
146 "loopA:\n\t"
147 "nop\n\t"
148 "dec r21\n\t"
149 "brne loopA\n\t"
150 /* Release bus */
151 "cbi %[ddr], %[pin]\n\t"
152 /* Delay B (64 usec) */
153 "ldi r21, 32\n\t"
154 "loopB:\n\t"
155 "nop\n\t"
156 "nop\n\t"
157 "nop\n\t"
158 "nop\n\t"
159 "nop\n\t"
160 "dec r21\n\t"
161 "brne loopB\n\t"
162 : /* Outputs */
163 : [out] "I" (_SFR_IO_ADDR(OWIREOUTPORT)), /* Inputs */
164 [ddr] "I" (_SFR_IO_ADDR(OWIREDDR)),
165 [pin] "I" (OWIREOUTPIN)
166 : "r21"); /* Clobbers */
167 } else { 148 } else {
168 asm volatile ( 149 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
169 /* Drive bus low */ 150 OWIREDDR |= _BV(OWIREOUTPIN);
170 "cbi %[out], %[pin]\n\t" 151 DELAY_C;
171 "sbi %[ddr], %[pin]\n\t" 152 OWIREDDR &= ~(_BV(OWIREOUTPIN));
172 /* Delay C (60 usec) */ 153 DELAY_D;
173 "ldi r21, 30\n\t"
174 "loopC:\n\t"
175 "nop\n\t"
176 "nop\n\t"
177 "nop\n\t"
178 "nop\n\t"
179 "nop\n\t"
180 "dec r21\n\t"
181 "brne loopC\n\t"
182 /* Release bus */
183 "cbi %[ddr], %[pin]\n\t"
184 /* Delay D (10 usec) */
185 "ldi r21, 9\n\t"
186 "loopD:\n\t"
187 "nop\n\t"
188 "dec r21\n\t"
189 "brne loopD\n\t"
190 : /* Outputs */
191 : [out] "I" (_SFR_IO_ADDR(OWIREOUTPORT)), /* Inputs */
192 [ddr] "I" (_SFR_IO_ADDR(OWIREDDR)),
193 [pin] "I" (OWIREOUTPIN)
194 : "r21"); /* Clobbers */
195 } 154 }
196 } 155 }
197 156
198 /*----------------------------------------------------------------------------- 157 /*-----------------------------------------------------------------------------
199 * Read a bit from the 1-wire bus and return it. 158 * Read a bit from the 1-wire bus and return it.
200 */ 159 */
201 int 160 int
202 OWReadBit(void) { 161 OWReadBit(void) {
203 uint8_t result;
204
205 OWdelay(); 162 OWdelay();
206 163
207 asm volatile ( 164 OWIREOUTPORT &= ~(_BV(OWIREOUTPIN));
208 /* Drive bus low */ 165 OWIREDDR |= _BV(OWIREOUTPIN);
209 "cbi %[out], %[opin]\n\t" 166 DELAY_A;
210 "sbi %[ddr], %[opin]\n\t" 167 OWIREDDR &= ~(_BV(OWIREOUTPIN));
211 /* Delay A (6 usec) */ 168 DELAY_E;
212 "ldi r21, 1\n\t" 169 return(OWIREINPORT & _BV(OWIREINPIN) ? 1 : 0);
213 "loopA1:\n\t"
214 "dec r21\n\t"
215 "brne loopA1\n\t"
216 /* Release bus */
217 "cbi %[ddr], %[opin]\n\t"
218 /* Delay E (9 usec) */
219 "ldi r21, 8\n\t"
220 "loopE:\n\t"
221 "nop\n\t"
222 "dec r21\n\t"
223 "brne loopE\n\t"
224 /* Sample */
225 "ldi %[res], 0\n\t"
226 "sbic %[in], %[ipin]\n\t"
227 "ldi %[res], 1\n\t"
228
229 /* Delay F (55 usec) */
230 "ldi r21, 27\n\t"
231 "loopF:\n\t"
232 "nop\n\t"
233 "nop\n\t"
234 "nop\n\t"
235 "nop\n\t"
236 "nop\n\t"
237 "nop\n\t"
238 "nop\n\t"
239 "nop\n\t"
240 "nop\n\t"
241 "nop\n\t"
242 "nop\n\t"
243 "nop\n\t"
244 "nop\n\t"
245 "dec r21\n\t"
246 "brne loopF\n\t"
247
248 : [res] "=r" (result) /* Outputs */
249 : [out] "I" (_SFR_IO_ADDR(OWIREOUTPORT)), /* Inputs */
250 [ddr] "I" (_SFR_IO_ADDR(OWIREDDR)),
251 [opin] "I" (OWIREOUTPIN),
252 [in] "I" (_SFR_IO_ADDR(OWIREINPORT)),
253 [ipin] "I" (OWIREINPIN)
254 : "r21"); /* Clobbers */
255
256 return(result);
257 } 170 }
258 171
259 /*----------------------------------------------------------------------------- 172 /*-----------------------------------------------------------------------------
260 * Write a byte to the 1-wire bus 173 * Write a byte to the 1-wire bus
261 */ 174 */