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   1 /*
   2  * Copyright © 2012 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  16  */
  17
  18 #include <ao.h>
  19 #include <ao_quadrature.h>
  20 #include <ao_exti.h>
  21
  22 __xdata int32_t ao_quadrature_count;
  23
  24 static uint8_t  ao_quadrature_state;
  25
  26 #define BIT(a,b)        ((a) | ((b) << 1))
  27 #define STATE(old_a, old_b, new_a, new_b)       (((BIT(old_a, old_b) << 2) | BIT(new_a, new_b)))
  28
  29 static void
  30 ao_quadrature_isr(void)
  31 {
  32         ao_quadrature_state = ((ao_quadrature_state & 3) << 2);
  33         ao_quadrature_state |= ao_gpio_get(AO_QUADRATURE_PORT, AO_QUADRATURE_A, AO_QUADRATURE_A_PIN);
  34         ao_quadrature_state |= ao_gpio_get(AO_QUADRATURE_PORT, AO_QUADRATURE_B, AO_QUADRATURE_B_PIN) << 1;
  35
  36         switch (ao_quadrature_state) {
  37         case STATE(0, 1, 0, 0):
  38                 ao_quadrature_count++;
  39                 break;
  40         case STATE(1, 0, 0, 0):
  41                 ao_quadrature_count--;
  42                 break;
  43         default:
  44                 return;
  45         }
  46         ao_wakeup(&ao_quadrature_count);
  47 }
  48
  49 int32_t
  50 ao_quadrature_poll(void)
  51 {
  52         int32_t ret;
  53         ao_arch_critical(ret = ao_quadrature_count;);
  54         return ret;
  55 }
  56
  57 int32_t
  58 ao_quadrature_wait(void)
  59 {
  60         ao_sleep(&ao_quadrature_count);
  61         return ao_quadrature_poll();
  62 }
  63
  64 static void
  65 ao_quadrature_test(void)
  66 {
  67 #if 1
  68         for (;;) {
  69                 int32_t c;
  70                 flush();
  71                 c = ao_quadrature_wait();
  72                 printf ("new count %6d\n", c);
  73                 if (c == 100)
  74                         break;
  75         }
  76 #endif
  77 #if 0
  78         uint8_t a, old_a, b, old_b;
  79
  80         old_a = 2; old_b = 2;
  81         for (;;) {
  82                 a = ao_gpio_get(AO_QUADRATURE_PORT, AO_QUADRATURE_A, AO_QUADRATURE_A_PIN);
  83                 b = ao_gpio_get(AO_QUADRATURE_PORT, AO_QUADRATURE_B, AO_QUADRATURE_B_PIN);
  84                 if (a != old_a || b != old_b) {
  85                         printf ("A %d B %d count %ld\n", a, b, ao_quadrature_count);
  86                         flush();
  87                         ao_yield();
  88                         old_a = a;
  89                         old_b = b;
  90                 }
  91                 if (ao_stdin_ready)
  92                         break;
  93         }
  94 #endif
  95 }
  96
  97 static const struct ao_cmds ao_quadrature_cmds[] = {
  98         { ao_quadrature_test,   "q\0Test quadrature" },
  99         { 0, NULL }
 100 };
 101
 102 void
 103 ao_quadrature_init(void)
 104 {
 105         ao_quadrature_count = 0;
 106
 107         ao_enable_port(AO_QUADRATURE_PORT);
 108         ao_exti_setup(AO_QUADRATURE_PORT, AO_QUADRATURE_A,
 109                       AO_EXTI_MODE_PULL_UP|AO_EXTI_MODE_FALLING|AO_EXTI_MODE_RISING|AO_EXTI_PRIORITY_MED,
 110                       ao_quadrature_isr);
 111         ao_exti_enable(AO_QUADRATURE_PORT, AO_QUADRATURE_A);
 112         ao_exti_setup(AO_QUADRATURE_PORT, AO_QUADRATURE_B,
 113                       AO_EXTI_MODE_PULL_UP|AO_EXTI_MODE_FALLING|AO_EXTI_MODE_RISING|AO_EXTI_PRIORITY_MED,
 114                       ao_quadrature_isr);
 115         ao_exti_enable(AO_QUADRATURE_PORT, AO_QUADRATURE_B);
 116         ao_cmd_register(&ao_quadrature_cmds[0]);
 117 }