diff options
Diffstat (limited to 'platforms/chibios/drivers/backlight_pwm.c')
| -rw-r--r-- | platforms/chibios/drivers/backlight_pwm.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/platforms/chibios/drivers/backlight_pwm.c b/platforms/chibios/drivers/backlight_pwm.c new file mode 100644 index 0000000000..01e6f71307 --- /dev/null +++ b/platforms/chibios/drivers/backlight_pwm.c @@ -0,0 +1,173 @@ +#include "backlight.h" +#include "gpio.h" +#include "wait.h" +#include <hal.h> + +// Maximum duty cycle limit +#ifndef BACKLIGHT_LIMIT_VAL +# define BACKLIGHT_LIMIT_VAL 255 +#endif + +#ifndef BACKLIGHT_PAL_MODE +# if defined(USE_GPIOV1) +# define BACKLIGHT_PAL_MODE PAL_MODE_ALTERNATE_PUSHPULL +# else +// GPIOV2 && GPIOV3 +# define BACKLIGHT_PAL_MODE 2 +# endif +#endif + +// GENERIC +#ifndef BACKLIGHT_PWM_DRIVER +# define BACKLIGHT_PWM_DRIVER PWMD4 +#endif +#ifndef BACKLIGHT_PWM_CHANNEL +# define BACKLIGHT_PWM_CHANNEL 3 +#endif + +// Support for pins which are on TIM1_CH1N - requires STM32_PWM_USE_ADVANCED +#ifdef BACKLIGHT_PWM_COMPLEMENTARY_OUTPUT +# if BACKLIGHT_ON_STATE == 1 +# define PWM_OUTPUT_MODE PWM_COMPLEMENTARY_OUTPUT_ACTIVE_LOW; +# else +# define PWM_OUTPUT_MODE PWM_COMPLEMENTARY_OUTPUT_ACTIVE_HIGH; +# endif +#else +# if BACKLIGHT_ON_STATE == 1 +# define PWM_OUTPUT_MODE PWM_OUTPUT_ACTIVE_HIGH; +# else +# define PWM_OUTPUT_MODE PWM_OUTPUT_ACTIVE_LOW; +# endif +#endif + +#ifndef BACKLIGHT_PWM_COUNTER_FREQUENCY +# define BACKLIGHT_PWM_COUNTER_FREQUENCY 0xFFFF +#endif + +#ifndef BACKLIGHT_PWM_PERIOD +# define BACKLIGHT_PWM_PERIOD 256 +#endif + +static PWMConfig pwmCFG = { + .frequency = BACKLIGHT_PWM_COUNTER_FREQUENCY, /* PWM clock frequency */ + .period = BACKLIGHT_PWM_PERIOD, /* PWM period in counter ticks. e.g. clock frequency is 10KHz, period is 256 ticks then t_period is 25.6ms */ +}; + +#ifdef BACKLIGHT_BREATHING +static virtual_timer_t breathing_vt; +#endif + +// See http://jared.geek.nz/2013/feb/linear-led-pwm +static uint16_t cie_lightness(uint16_t v) { + if (v <= 5243) // if below 8% of max + return v / 9; // same as dividing by 900% + else { + uint32_t y = (((uint32_t)v + 10486) << 8) / (10486 + 0xFFFFUL); // add 16% of max and compare + // to get a useful result with integer division, we shift left in the expression above + // and revert what we've done again after squaring. + y = y * y * y >> 8; + if (y > 0xFFFFUL) { // prevent overflow + return 0xFFFFU; + } else { + return (uint16_t)y; + } + } +} + +static uint32_t rescale_limit_val(uint32_t val) { + // rescale the supplied backlight value to be in terms of the value limit + return (val * (BACKLIGHT_LIMIT_VAL + 1)) / 256; +} + +void backlight_init_ports(void) { +#ifdef USE_GPIOV1 + palSetPadMode(PAL_PORT(BACKLIGHT_PIN), PAL_PAD(BACKLIGHT_PIN), BACKLIGHT_PAL_MODE); +#else + palSetPadMode(PAL_PORT(BACKLIGHT_PIN), PAL_PAD(BACKLIGHT_PIN), PAL_MODE_ALTERNATE(BACKLIGHT_PAL_MODE)); +#endif + + pwmCFG.channels[BACKLIGHT_PWM_CHANNEL - 1].mode = PWM_OUTPUT_MODE; + pwmStart(&BACKLIGHT_PWM_DRIVER, &pwmCFG); + + backlight_set(get_backlight_level()); + +#ifdef BACKLIGHT_BREATHING + chVTObjectInit(&breathing_vt); + if (is_backlight_breathing()) { + breathing_enable(); + } +#endif +} + +void backlight_set(uint8_t level) { + if (level > BACKLIGHT_LEVELS) { + level = BACKLIGHT_LEVELS; + } + + if (level == 0) { + // Turn backlight off + pwmDisableChannel(&BACKLIGHT_PWM_DRIVER, BACKLIGHT_PWM_CHANNEL - 1); + } else { + // Turn backlight on + uint32_t duty = (uint32_t)(cie_lightness(rescale_limit_val(0xFFFF * (uint32_t)level / BACKLIGHT_LEVELS))); + pwmEnableChannel(&BACKLIGHT_PWM_DRIVER, BACKLIGHT_PWM_CHANNEL - 1, PWM_FRACTION_TO_WIDTH(&BACKLIGHT_PWM_DRIVER, 0xFFFF, duty)); + } +} + +void backlight_task(void) {} + +#ifdef BACKLIGHT_BREATHING + +# define BREATHING_STEPS 128 + +/* To generate breathing curve in python: + * from math import sin, pi; [int(sin(x/128.0*pi)**4*255) for x in range(128)] + */ +static const uint8_t breathing_table[BREATHING_STEPS] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 17, 20, 24, 28, 32, 36, 41, 46, 51, 57, 63, 70, 76, 83, 91, 98, 106, 113, 121, 129, 138, 146, 154, 162, 170, 178, 185, 193, 200, 207, 213, 220, 225, 231, 235, 240, 244, 247, 250, 252, 253, 254, 255, 254, 253, 252, 250, 247, 244, 240, 235, 231, 225, 220, 213, 207, 200, 193, 185, 178, 170, 162, 154, 146, 138, 129, 121, 113, 106, 98, 91, 83, 76, 70, 63, 57, 51, 46, 41, 36, 32, 28, 24, 20, 17, 15, 12, 10, 8, 6, 5, 4, 3, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; + +static void breathing_callback(virtual_timer_t *vtp, void *p); + +bool is_breathing(void) { + return chVTIsArmed(&breathing_vt); +} + +void breathing_enable(void) { + /* Update frequency is 256Hz -> 3906us intervals */ + chVTSetContinuous(&breathing_vt, TIME_US2I(3906), breathing_callback, NULL); +} + +void breathing_disable(void) { + chVTReset(&breathing_vt); + + // Restore backlight level + backlight_set(get_backlight_level()); +} + +// Use this before the cie_lightness function. +static inline uint16_t scale_backlight(uint16_t v) { + return v / BACKLIGHT_LEVELS * get_backlight_level(); +} + +static void breathing_callback(virtual_timer_t *vtp, void *p) { + uint8_t breathing_period = get_breathing_period(); + uint16_t interval = (uint16_t)breathing_period * 256 / BREATHING_STEPS; + + // resetting after one period to prevent ugly reset at overflow. + static uint16_t breathing_counter = 0; + breathing_counter = (breathing_counter + 1) % (breathing_period * 256); + uint8_t index = breathing_counter / interval % BREATHING_STEPS; + uint32_t duty = cie_lightness(rescale_limit_val(scale_backlight(breathing_table[index] * 256))); + + chSysLockFromISR(); + pwmEnableChannelI(&BACKLIGHT_PWM_DRIVER, BACKLIGHT_PWM_CHANNEL - 1, PWM_FRACTION_TO_WIDTH(&BACKLIGHT_PWM_DRIVER, 0xFFFF, duty)); + chSysUnlockFromISR(); +} + +// TODO: integrate generic pulse solution +void breathing_pulse(void) { + backlight_set(is_backlight_enabled() ? 0 : BACKLIGHT_LEVELS); + wait_ms(10); + backlight_set(is_backlight_enabled() ? get_backlight_level() : 0); +} + +#endif |