backlight_timer.c (5259B)
1 #include "backlight.h" 2 #include "backlight_driver_common.h" 3 #include "wait.h" 4 5 #ifndef BACKLIGHT_GPT_DRIVER 6 # define BACKLIGHT_GPT_DRIVER GPTD15 7 #endif 8 9 // Platform specific implementations 10 static void backlight_timer_configure(bool enable); 11 static void backlight_timer_set_duty(uint16_t duty); 12 static uint16_t backlight_timer_get_duty(void); 13 14 // See http://jared.geek.nz/2013/feb/linear-led-pwm 15 static uint16_t cie_lightness(uint16_t v) { 16 if (v <= 5243) // if below 8% of max 17 return v / 9; // same as dividing by 900% 18 else { 19 uint32_t y = (((uint32_t)v + 10486) << 8) / (10486 + 0xFFFFUL); // add 16% of max and compare 20 // to get a useful result with integer division, we shift left in the expression above 21 // and revert what we've done again after squaring. 22 y = y * y * y >> 8; 23 if (y > 0xFFFFUL) // prevent overflow 24 return 0xFFFFU; 25 else 26 return (uint16_t)y; 27 } 28 } 29 30 void backlight_init_ports(void) { 31 backlight_pins_init(); 32 33 backlight_set(get_backlight_level()); 34 35 #ifdef BACKLIGHT_BREATHING 36 if (is_backlight_breathing()) { 37 breathing_enable(); 38 } 39 #endif 40 } 41 42 void backlight_set(uint8_t level) { 43 if (level > BACKLIGHT_LEVELS) level = BACKLIGHT_LEVELS; 44 45 backlight_pins_off(); 46 47 backlight_timer_set_duty(cie_lightness(0xFFFFU / BACKLIGHT_LEVELS * level)); 48 backlight_timer_configure(level != 0); 49 } 50 51 static void backlight_timer_top(void) { 52 #ifdef BACKLIGHT_BREATHING 53 if (is_breathing()) { 54 breathing_task(); 55 } 56 #endif 57 58 if (backlight_timer_get_duty() > 256) { 59 backlight_pins_on(); 60 } 61 } 62 63 static void backlight_timer_cmp(void) { 64 backlight_pins_off(); 65 } 66 67 void backlight_task(void) {} 68 69 #ifdef BACKLIGHT_BREATHING 70 # define BREATHING_STEPS 128 71 72 static bool breathing = false; 73 static uint16_t breathing_counter = 0; 74 75 /* To generate breathing curve in python: 76 * from math import sin, pi; [int(sin(x/128.0*pi)**4*255) for x in range(128)] 77 */ 78 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}; 79 80 // Use this before the cie_lightness function. 81 static inline uint16_t scale_backlight(uint16_t v) { 82 return v / BACKLIGHT_LEVELS * get_backlight_level(); 83 } 84 85 void breathing_task(void) { 86 uint8_t breathing_period = get_breathing_period(); 87 uint16_t interval = (uint16_t)breathing_period * 256 / BREATHING_STEPS; 88 // resetting after one period to prevent ugly reset at overflow. 89 breathing_counter = (breathing_counter + 1) % (breathing_period * 256); 90 uint8_t index = breathing_counter / interval % BREATHING_STEPS; 91 92 // printf("index:%u\n", index); 93 94 backlight_timer_set_duty(cie_lightness(scale_backlight((uint16_t)breathing_table[index] * 256))); 95 } 96 97 bool is_breathing(void) { 98 return breathing; 99 } 100 101 void breathing_enable(void) { 102 breathing_counter = 0; 103 breathing = true; 104 } 105 void breathing_disable(void) { 106 breathing = false; 107 } 108 109 void breathing_pulse(void) { 110 backlight_set(is_backlight_enabled() ? 0 : BACKLIGHT_LEVELS); 111 wait_ms(10); 112 backlight_set(is_backlight_enabled() ? get_backlight_level() : 0); 113 } 114 #endif 115 116 #ifdef PROTOCOL_CHIBIOS 117 // On Platforms where timers fire every tick and have no capture/top events 118 // - fake event in the normal timer callback 119 uint16_t s_duty = 0; 120 121 static void timerCallback(void) { 122 /* Software PWM 123 * timer:1111 1111 1111 1111 124 * \______/| \_______/____ count(0-255) 125 * \ \______________ unused(1) 126 * \__________________ index of step table(0-127) 127 */ 128 129 // this works for cca 65536 irqs/sec 130 static union { 131 uint16_t raw; 132 struct { 133 uint16_t count : 8; 134 uint8_t dummy : 1; 135 uint8_t index : 7; 136 } pwm; 137 } timer = {.raw = 0}; 138 139 timer.raw++; 140 141 if (timer.pwm.count == 0) { 142 // LED on 143 backlight_timer_top(); 144 } else if (timer.pwm.count == (s_duty / 256)) { 145 // LED off 146 backlight_timer_cmp(); 147 } 148 } 149 150 static void backlight_timer_set_duty(uint16_t duty) { 151 s_duty = duty; 152 } 153 static uint16_t backlight_timer_get_duty(void) { 154 return s_duty; 155 } 156 157 // ChibiOS - Map GPT timer onto Software PWM 158 static void gptTimerCallback(GPTDriver *gptp) { 159 (void)gptp; 160 timerCallback(); 161 } 162 163 static void backlight_timer_configure(bool enable) { 164 static const GPTConfig gptcfg = {1000000, gptTimerCallback, 0, 0}; 165 166 static bool s_init = false; 167 if (!s_init) { 168 gptStart(&BACKLIGHT_GPT_DRIVER, &gptcfg); 169 s_init = true; 170 } 171 172 if (enable) { 173 gptStartContinuous(&BACKLIGHT_GPT_DRIVER, gptcfg.frequency / 0xFFFF); 174 } else { 175 gptStopTimer(&BACKLIGHT_GPT_DRIVER); 176 } 177 } 178 #endif