--- /dev/null
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+#include <ao_quadrature.h>
+#include <ao_exti.h>
+
+__xdata int32_t ao_quadrature_count;
+
+static uint8_t wait_clear;
+
+static void
+ao_quadrature_isr(void)
+{
+ if (wait_clear) {
+ wait_clear = 0;
+ ao_exti_set_mode(AO_QUADRATURE_PORT, AO_QUADRATURE_A, AO_EXTI_MODE_RISING);
+ } else {
+ wait_clear = 1;
+ ao_exti_set_mode(AO_QUADRATURE_PORT, AO_QUADRATURE_A, AO_EXTI_MODE_FALLING);
+ if (ao_gpio_get(AO_QUADRATURE_PORT, AO_QUADRATURE_B, AO_QUADRATURE_B_PIN))
+ ao_quadrature_count++;
+ else
+ ao_quadrature_count--;
+ ao_wakeup(&ao_quadrature_count);
+ }
+}
+
+int32_t
+ao_quadrature_poll(void)
+{
+ int32_t ret;
+ ao_arch_critical(ret = ao_quadrature_count;);
+ return ret;
+}
+
+int32_t
+ao_quadrature_wait(void)
+{
+ ao_sleep(&ao_quadrature_count);
+ return ao_quadrature_poll();
+}
+
+static void
+ao_quadrature_test(void)
+{
+#if 0
+ for (;;) {
+ int32_t c;
+ printf ("waiting...\n");
+ flush();
+ c = ao_quadrature_wait();
+ printf ("new count %d\n", c);
+ if (ao_stdin_ready)
+ break;
+ }
+#endif
+ uint8_t a, old_a, b, old_b;
+
+ old_a = 2; old_b = 2;
+ for (;;) {
+ a = ao_gpio_get(AO_QUADRATURE_PORT, AO_QUADRATURE_A, AO_QUADRATURE_A_PIN);
+ b = ao_gpio_get(AO_QUADRATURE_PORT, AO_QUADRATURE_B, AO_QUADRATURE_B_PIN);
+ if (a != old_a || b != old_b) {
+ printf ("A %d B %d\n", a, b);
+ flush();
+ ao_yield();
+ old_a = a;
+ old_b = b;
+ }
+ if (ao_stdin_ready)
+ break;
+ }
+
+}
+
+static const struct ao_cmds ao_quadrature_cmds[] = {
+ { ao_quadrature_test, "q\0Test quadrature" },
+ { 0, NULL }
+};
+
+void
+ao_quadrature_init(void)
+{
+ ao_quadrature_count = 0;
+
+ ao_enable_port(AO_QUADRATURE_PORT);
+ ao_exti_setup(AO_QUADRATURE_PORT, AO_QUADRATURE_A,
+ AO_EXTI_MODE_PULL_UP|AO_EXTI_MODE_FALLING|AO_EXTI_PRIORITY_MED,
+ ao_quadrature_isr);
+ ao_exti_enable(AO_QUADRATURE_PORT, AO_QUADRATURE_A);
+ ao_enable_input(AO_QUADRATURE_PORT, AO_QUADRATURE_B, AO_EXTI_MODE_PULL_UP);
+ ao_cmd_register(&ao_quadrature_cmds[0]);
+}
--- /dev/null
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#ifndef _AO_QUADRATURE_H_
+#define _AO_QUADRATURE_H_
+
+int32_t
+ao_quadrature_wait(void);
+
+int32_t
+ao_quadrature_poll(void);
+
+void
+ao_quadrature_init(void);
+
+#endif /* _AO_QUADRATURE_H_ */