+/*
+ * Copyright © 2013 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_debounce.h>
+
+static uint8_t ao_debounce_initialized;
+static uint8_t ao_debounce_running;
+static struct ao_debounce *ao_debounce;
+
+static void
+ao_debounce_on(void)
+{
+ stm_tim6.cr1 = ((0 << STM_TIM67_CR1_ARPE) |
+ (0 << STM_TIM67_CR1_OPM) |
+ (1 << STM_TIM67_CR1_URS) |
+ (0 << STM_TIM67_CR1_UDIS) |
+ (1 << STM_TIM67_CR1_CEN));
+}
+
+static void
+ao_debounce_off(void)
+{
+ stm_tim6.cr1 = ((0 << STM_TIM67_CR1_ARPE) |
+ (0 << STM_TIM67_CR1_OPM) |
+ (1 << STM_TIM67_CR1_URS) |
+ (0 << STM_TIM67_CR1_UDIS) |
+ (0 << STM_TIM67_CR1_CEN));
+}
+
+static void
+_ao_debounce_set(struct ao_debounce *debounce, uint8_t value)
+{
+ if (value != debounce->value) {
+ debounce->value = value;
+ debounce->_set(debounce, value);
+ }
+ _ao_debounce_stop(debounce);
+}
+
+/*
+ * Get the current value, set the result when we've
+ * reached the debounce count limit
+ */
+static void
+_ao_debounce_check(struct ao_debounce *debounce)
+{
+ if (debounce->_get(debounce)) {
+ if (debounce->count < 0)
+ debounce->count = 0;
+ if (debounce->count < debounce->hold) {
+ if (++debounce->count == debounce->hold)
+ _ao_debounce_set(debounce, 1);
+ }
+ } else {
+ if (debounce->count > 0)
+ debounce->count = 0;
+ if (debounce->count > -debounce->hold) {
+ if (--debounce->count == -debounce->hold)
+ _ao_debounce_set(debounce, 0);
+ }
+ }
+}
+
+/*
+ * Start monitoring one pin
+ */
+void
+_ao_debounce_start(struct ao_debounce *debounce)
+{
+ if (debounce->running)
+ return;
+ debounce->running = 1;
+
+ /* Reset the counter */
+ debounce->count = 0;
+
+ /* Link into list */
+ debounce->next = ao_debounce;
+ ao_debounce = debounce;
+
+ /* Make sure the timer is running */
+ if (!ao_debounce_running++)
+ ao_debounce_on();
+
+ /* And go check the current value */
+ _ao_debounce_check(debounce);
+}
+
+/*
+ * Stop monitoring one pin
+ */
+void
+_ao_debounce_stop(struct ao_debounce *debounce)
+{
+ struct ao_debounce **prev;
+ if (!debounce->running)
+ return;
+
+ debounce->running = 0;
+
+ /* Unlink */
+ for (prev = &ao_debounce; (*prev); prev = &((*prev)->next)) {
+ if (*prev == debounce) {
+ *prev = debounce->next;
+ break;
+ }
+ }
+ debounce->next = NULL;
+
+ /* Turn off the timer if possible */
+ if (!--ao_debounce_running)
+ ao_debounce_off();
+}
+
+void stm_tim6_isr(void)
+{
+ struct ao_debounce *debounce, *next;
+ if (stm_tim6.sr & (1 << STM_TIM67_SR_UIF)) {
+ stm_tim6.sr = 0;
+
+ /* Walk the current list, allowing the current
+ * object to be removed from the list
+ */
+ for (debounce = ao_debounce; debounce; debounce = next) {
+ next = debounce->next;
+ _ao_debounce_check(debounce);
+ }
+ }
+}
+
+/*
+ * According to the STM clock-configuration, timers run
+ * twice as fast as the APB1 clock *if* the APB1 prescaler
+ * is greater than 1.
+ */
+
+#if AO_APB1_PRESCALER > 1
+#define TIMER_23467_SCALER 2
+#else
+#define TIMER_23467_SCALER 1
+#endif
+
+#define TIMER_100kHz ((AO_PCLK1 * TIMER_23467_SCALER) / 100000)
+
+void
+ao_debounce_init(void)
+{
+ if (ao_debounce_initialized)
+ return;
+ ao_debounce_initialized = 1;
+
+ stm_nvic_set_enable(STM_ISR_TIM6_POS);
+ stm_nvic_set_priority(STM_ISR_TIM6_POS, AO_STM_NVIC_CLOCK_PRIORITY);
+
+ /* Turn on timer 6 */
+ stm_rcc.apb1enr |= (1 << STM_RCC_APB1ENR_TIM6EN);
+
+ stm_tim6.psc = TIMER_100kHz;
+ stm_tim6.arr = 9;
+ stm_tim6.cnt = 0;
+
+ /* Enable update interrupt */
+ stm_tim6.dier = (1 << STM_TIM67_DIER_UIE);
+
+ /* Poke timer to reload values */
+ stm_tim6.egr |= (1 << STM_TIM67_EGR_UG);
+
+ stm_tim6.cr2 = (STM_TIM67_CR2_MMS_RESET << STM_TIM67_CR2_MMS);
+
+ /* And turn it off (for now) */
+ ao_debounce_off();
+}
projects / fw / altos / commitdiff