diff options
Diffstat (limited to 'src/stm')
| -rw-r--r-- | src/stm/ao_debounce.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/src/stm/ao_debounce.c b/src/stm/ao_debounce.c new file mode 100644 index 00000000..22cdf230 --- /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(); +} |