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-rw-r--r--quantum/backlight/backlight_soft.c37
1 files changed, 30 insertions, 7 deletions
diff --git a/quantum/backlight/backlight_soft.c b/quantum/backlight/backlight_soft.c
index a6aba7782c..f481dbae89 100644
--- a/quantum/backlight/backlight_soft.c
+++ b/quantum/backlight/backlight_soft.c
@@ -20,6 +20,7 @@
{ BACKLIGHT_PIN }
#endif
+static uint16_t s_duty_pattern = 0;
static const pin_t backlight_pins[] = BACKLIGHT_PIN_INIT;
#define BACKLIGHT_LED_COUNT (sizeof(backlight_pins) / sizeof(pin_t))
@@ -46,21 +47,43 @@ void backlight_off(pin_t backlight_pin) {
}
void backlight_init_ports(void) {
- // Setup backlight pin as output and output to on state.
- FOR_EACH_LED(setPinOutput(backlight_pin); backlight_on(backlight_pin);)
+ // Setup backlight pin as output and output to off state.
+ FOR_EACH_LED(setPinOutput(backlight_pin); backlight_off(backlight_pin);)
}
+// clang-format off
+
+/** \brief PWM duty patterns
+ *
+ * We scale the current backlight level to an index within this array. This allows
+ * backlight_task to focus on just switching LEDs on/off, and we can predict the duty pattern
+ */
+static uint16_t backlight_duty_table[] = {
+ 0b0000000000000000,
+ 0b1000000000000000,
+ 0b1000000010000000,
+ 0b1000001000010000,
+ 0b1000100010001000,
+ 0b1001001001001000,
+ 0b1010101010101010,
+ 0b1110111011101110,
+ 0b1111111111111111,
+};
+#define backlight_duty_table_size (sizeof(backlight_duty_table) / sizeof(backlight_duty_table[0]))
+
+// clang-format on
+
+static uint8_t scale_backlight(uint8_t v) { return v * (backlight_duty_table_size - 1) / BACKLIGHT_LEVELS; }
+
+void backlight_set(uint8_t level) { s_duty_pattern = backlight_duty_table[scale_backlight(level)]; }
+
void backlight_task(void) {
static uint8_t backlight_tick = 0;
- if ((0xFFFF >> (get_backlight_level() * ((BACKLIGHT_LEVELS + 1) / 2))) & (1 << backlight_tick)) {
+ if (s_duty_pattern & ((uint16_t)1 << backlight_tick)) {
FOR_EACH_LED(backlight_on(backlight_pin);)
} else {
FOR_EACH_LED(backlight_off(backlight_pin);)
}
backlight_tick = (backlight_tick + 1) % 16;
}
-
-void backlight_set(uint8_t level) {
- // noop as backlight_task uses get_backlight_level()
-}