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ARM backlight - timer implementation (#8291)
* Add GPT timer based backlight driver * Update to tim15 to avoid conflict with audio * Update quantum/backlight/backlight_timer.c
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#include "quantum.h" | ||
#include "backlight.h" | ||
#include "backlight_driver_common.h" | ||
#include "debug.h" | ||
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#ifndef BACKLIGHT_GPT_DRIVER | ||
# define BACKLIGHT_GPT_DRIVER GPTD15 | ||
#endif | ||
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// 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); | ||
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// 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; | ||
} | ||
} | ||
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void backlight_init_ports(void) { | ||
backlight_pins_init(); | ||
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backlight_set(get_backlight_level()); | ||
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#ifdef BACKLIGHT_BREATHING | ||
if (is_backlight_breathing()) { | ||
breathing_enable(); | ||
} | ||
#endif | ||
} | ||
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void backlight_set(uint8_t level) { | ||
if (level > BACKLIGHT_LEVELS) level = BACKLIGHT_LEVELS; | ||
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backlight_pins_off(); | ||
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backlight_timer_set_duty(cie_lightness(0xFFFFU / BACKLIGHT_LEVELS * level)); | ||
backlight_timer_configure(level != 0); | ||
} | ||
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static void backlight_timer_top(void) { | ||
#ifdef BACKLIGHT_BREATHING | ||
if (is_breathing()) { | ||
breathing_task(); | ||
} | ||
#endif | ||
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if (backlight_timer_get_duty() > 256) { | ||
backlight_pins_on(); | ||
} | ||
} | ||
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static void backlight_timer_cmp(void) { backlight_pins_off(); } | ||
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void backlight_task(void) {} | ||
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#ifdef BACKLIGHT_BREATHING | ||
# define BREATHING_STEPS 128 | ||
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static bool breathing = false; | ||
static uint16_t breathing_counter = 0; | ||
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/* 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}; | ||
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// Use this before the cie_lightness function. | ||
static inline uint16_t scale_backlight(uint16_t v) { return v / BACKLIGHT_LEVELS * get_backlight_level(); } | ||
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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; | ||
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// printf("index:%u\n", index); | ||
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backlight_timer_set_duty(cie_lightness(scale_backlight((uint16_t)breathing_table[index] * 256))); | ||
} | ||
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bool is_breathing(void) { return breathing; } | ||
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void breathing_enable(void) { | ||
breathing_counter = 0; | ||
breathing = true; | ||
} | ||
void breathing_disable(void) { breathing = false; } | ||
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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 | ||
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#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; | ||
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static void timerCallback(void) { | ||
/* Software PWM | ||
* timer:1111 1111 1111 1111 | ||
* \______/| \_______/____ count(0-255) | ||
* \ \______________ unused(1) | ||
* \__________________ index of step table(0-127) | ||
*/ | ||
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// 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}; | ||
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timer.raw++; | ||
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if (timer.pwm.count == 0) { | ||
// LED on | ||
backlight_timer_top(); | ||
} else if (timer.pwm.count == (s_duty / 256)) { | ||
// LED off | ||
backlight_timer_cmp(); | ||
} | ||
} | ||
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static void backlight_timer_set_duty(uint16_t duty) { s_duty = duty; } | ||
static uint16_t backlight_timer_get_duty(void) { return s_duty; } | ||
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// ChibiOS - Map GPT timer onto Software PWM | ||
static void gptTimerCallback(GPTDriver *gptp) { | ||
(void)gptp; | ||
timerCallback(); | ||
} | ||
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static void backlight_timer_configure(bool enable) { | ||
static const GPTConfig gptcfg = {1000000, gptTimerCallback, 0, 0}; | ||
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static bool s_init = false; | ||
if (!s_init) { | ||
gptStart(&BACKLIGHT_GPT_DRIVER, &gptcfg); | ||
s_init = true; | ||
} | ||
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if (enable) { | ||
gptStartContinuous(&BACKLIGHT_GPT_DRIVER, gptcfg.frequency / 0xFFFF); | ||
} else { | ||
gptStopTimer(&BACKLIGHT_GPT_DRIVER); | ||
} | ||
} | ||
#endif |