altos: Add debounce helper. Use in button and quadrature drivers for TeleLCO

[fw/altos] / src / stm / ao_debounce.c

diff --git a/src/stm/ao_debounce.c b/src/stm/ao_debounce.c
new file mode 100644 (file)
index 0000000..22cdf23
--- /dev/null
+++ b/src/stm/ao_debounce.c
@@ -0,0 +1,187 @@
+/*
+ * 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();
+}