diff options
Diffstat (limited to 'platforms/chibios/drivers/backlight_timer.c')
| -rw-r--r-- | platforms/chibios/drivers/backlight_timer.c | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/platforms/chibios/drivers/backlight_timer.c b/platforms/chibios/drivers/backlight_timer.c new file mode 100644 index 0000000000..0fabee93b1 --- /dev/null +++ b/platforms/chibios/drivers/backlight_timer.c @@ -0,0 +1,178 @@ +#include "backlight.h" +#include "backlight_driver_common.h" +#include "wait.h" + +#ifndef BACKLIGHT_GPT_DRIVER +# define BACKLIGHT_GPT_DRIVER GPTD15 +#endif + +// Platform specific implementations +static void backlight_timer_configure(bool enable); +static void backlight_timer_set_duty(uint16_t duty); +static uint16_t backlight_timer_get_duty(void); + +// 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; + } +} + +void backlight_init_ports(void) { + backlight_pins_init(); + + backlight_set(get_backlight_level()); + +#ifdef BACKLIGHT_BREATHING + if (is_backlight_breathing()) { + breathing_enable(); + } +#endif +} + +void backlight_set(uint8_t level) { + if (level > BACKLIGHT_LEVELS) level = BACKLIGHT_LEVELS; + + backlight_pins_off(); + + backlight_timer_set_duty(cie_lightness(0xFFFFU / BACKLIGHT_LEVELS * level)); + backlight_timer_configure(level != 0); +} + +static void backlight_timer_top(void) { +#ifdef BACKLIGHT_BREATHING + if (is_breathing()) { + breathing_task(); + } +#endif + + if (backlight_timer_get_duty() > 256) { + backlight_pins_on(); + } +} + +static void backlight_timer_cmp(void) { + backlight_pins_off(); +} + +void backlight_task(void) {} + +#ifdef BACKLIGHT_BREATHING +# define BREATHING_STEPS 128 + +static bool breathing = false; +static uint16_t breathing_counter = 0; + +/* 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}; + +// Use this before the cie_lightness function. +static inline uint16_t scale_backlight(uint16_t v) { + return v / BACKLIGHT_LEVELS * get_backlight_level(); +} + +void breathing_task(void) { + 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. + breathing_counter = (breathing_counter + 1) % (breathing_period * 256); + uint8_t index = breathing_counter / interval % BREATHING_STEPS; + + // printf("index:%u\n", index); + + backlight_timer_set_duty(cie_lightness(scale_backlight((uint16_t)breathing_table[index] * 256))); +} + +bool is_breathing(void) { + return breathing; +} + +void breathing_enable(void) { + breathing_counter = 0; + breathing = true; +} +void breathing_disable(void) { + breathing = false; +} + +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 + +#ifdef PROTOCOL_CHIBIOS +// On Platforms where timers fire every tick and have no capture/top events +// - fake event in the normal timer callback +uint16_t s_duty = 0; + +static void timerCallback(void) { + /* Software PWM + * timer:1111 1111 1111 1111 + * \______/| \_______/____ count(0-255) + * \ \______________ unused(1) + * \__________________ index of step table(0-127) + */ + + // this works for cca 65536 irqs/sec + static union { + uint16_t raw; + struct { + uint16_t count : 8; + uint8_t dummy : 1; + uint8_t index : 7; + } pwm; + } timer = {.raw = 0}; + + timer.raw++; + + if (timer.pwm.count == 0) { + // LED on + backlight_timer_top(); + } else if (timer.pwm.count == (s_duty / 256)) { + // LED off + backlight_timer_cmp(); + } +} + +static void backlight_timer_set_duty(uint16_t duty) { + s_duty = duty; +} +static uint16_t backlight_timer_get_duty(void) { + return s_duty; +} + +// ChibiOS - Map GPT timer onto Software PWM +static void gptTimerCallback(GPTDriver *gptp) { + (void)gptp; + timerCallback(); +} + +static void backlight_timer_configure(bool enable) { + static const GPTConfig gptcfg = {1000000, gptTimerCallback, 0, 0}; + + static bool s_init = false; + if (!s_init) { + gptStart(&BACKLIGHT_GPT_DRIVER, &gptcfg); + s_init = true; + } + + if (enable) { + gptStartContinuous(&BACKLIGHT_GPT_DRIVER, gptcfg.frequency / 0xFFFF); + } else { + gptStopTimer(&BACKLIGHT_GPT_DRIVER); + } +} +#endif |