Rescale both ChibiOS and AVR backlighting. (#10260)

qmk · Oct 23, 2020 · 5720202 · 5720202
2 parents eee2f77 + 12cefd6
commit 5720202
Show file tree

Hide file tree

Showing 3 changed files with 33 additions and 12 deletions.
diff --git a/docs/feature_backlight.md b/docs/feature_backlight.md
@@ -62,14 +62,15 @@ Valid driver values are `pwm`, `software`, `custom` or `no`. See below for help
 
 To configure the backlighting, `#define` these in your `config.h`:
 
-|Define |Default |Description |
-|---------------------|-------------|-------------------------------------------------------------------------------------|
-|`BACKLIGHT_PIN` |*Not defined*|The pin that controls the LED(s) |
-|`BACKLIGHT_LEVELS` |`3` |The number of brightness levels (maximum 31 excluding off) |
-|`BACKLIGHT_CAPS_LOCK`|*Not defined*|Enable Caps Lock indicator using backlight (for keyboards without dedicated LED) |
-|`BACKLIGHT_BREATHING`|*Not defined*|Enable backlight breathing, if supported |
-|`BREATHING_PERIOD` |`6` |The length of one backlight "breath" in seconds |
-|`BACKLIGHT_ON_STATE` |`1` |The state of the backlight pin when the backlight is "on" - `1` for high, `0` for low|
+| Define | Default | Description |
+|------------------------|---------------|-------------------------------------------------------------------------------------------------------------------|
+| `BACKLIGHT_PIN` | *Not defined* | The pin that controls the LED(s) |
+| `BACKLIGHT_LEVELS` | `3` | The number of brightness levels (maximum 31 excluding off) |
+| `BACKLIGHT_CAPS_LOCK` | *Not defined* | Enable Caps Lock indicator using backlight (for keyboards without dedicated LED) |
+| `BACKLIGHT_BREATHING` | *Not defined* | Enable backlight breathing, if supported |
+| `BREATHING_PERIOD` | `6` | The length of one backlight "breath" in seconds |
+| `BACKLIGHT_ON_STATE` | `1` | The state of the backlight pin when the backlight is "on" - `1` for high, `0` for low |
+| `BACKLIGHT_LIMIT_VAL ` | `255` | The maximum duty cycle of the backlight -- `255` allows for full brightness, any lower will decrease the maximum. |
 
 Unless you are designing your own keyboard, you generally should not need to change the `BACKLIGHT_PIN` or `BACKLIGHT_ON_STATE`.
 

diff --git a/quantum/backlight/backlight_avr.c b/quantum/backlight/backlight_avr.c
@@ -3,6 +3,11 @@
 #include "backlight_driver_common.h"
 #include "debug.h"
 
+// Maximum duty cycle limit
+#ifndef BACKLIGHT_LIMIT_VAL
+# define BACKLIGHT_LIMIT_VAL 255
+#endif
+
 // This logic is a bit complex, we support 3 setups:
 //
 // 1. Hardware PWM when backlight is wired to a PWM pin.
@@ -240,6 +245,11 @@ static uint16_t cie_lightness(uint16_t v) {
  }
 }
 
+// rescale the supplied backlight value to be in terms of the value limit
+static uint32_t rescale_limit_val(uint32_t val) {
+ return (val * (BACKLIGHT_LIMIT_VAL + 1)) / 256;
+}
+
 // range for val is [0..TIMER_TOP]. PWM pin is high while the timer count is below val.
 static inline void set_pwm(uint16_t val) { OCRxx = val; }
 
@@ -269,7 +279,7 @@ void backlight_set(uint8_t level) {
 #endif
  }
  // Set the brightness
- set_pwm(cie_lightness(TIMER_TOP * (uint32_t)level / BACKLIGHT_LEVELS));
+ set_pwm(cie_lightness(rescale_limit_val(TIMER_TOP * (uint32_t)level / BACKLIGHT_LEVELS)));
 }
 
 void backlight_task(void) {}
@@ -375,7 +385,7 @@ ISR(TIMERx_OVF_vect)
  breathing_interrupt_disable();
  }
 
- set_pwm(cie_lightness(scale_backlight((uint16_t)pgm_read_byte(&breathing_table[index]) * 0x0101U)));
+ set_pwm(cie_lightness(rescale_limit_val(scale_backlight((uint16_t)pgm_read_byte(&breathing_table[index]) * 0x0101U))));
 }
 
 #endif // BACKLIGHT_BREATHING

diff --git a/quantum/backlight/backlight_chibios.c b/quantum/backlight/backlight_chibios.c
@@ -3,6 +3,11 @@
 #include <hal.h>
 #include "debug.h"
 
+// Maximum duty cycle limit
+#ifndef BACKLIGHT_LIMIT_VAL
+# define BACKLIGHT_LIMIT_VAL 255
+#endif
+
 // GPIOV2 && GPIOV3
 #ifndef BACKLIGHT_PAL_MODE
 # define BACKLIGHT_PAL_MODE 2
@@ -58,6 +63,11 @@ static uint16_t cie_lightness(uint16_t v) {
  }
 }
 
+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), PAL_MODE_STM32_ALTERNATE_PUSHPULL);
@@ -85,7 +95,7 @@ void backlight_set(uint8_t level) {
  pwmDisableChannel(&BACKLIGHT_PWM_DRIVER, BACKLIGHT_PWM_CHANNEL - 1);
  } else {
  // Turn backlight on
- uint32_t duty = (uint32_t)(cie_lightness(0xFFFF * (uint32_t)level / BACKLIGHT_LEVELS));
+ 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));
  }
 }
@@ -129,7 +139,7 @@ void breathing_callback(PWMDriver *pwmp) {
  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(scale_backlight(breathing_table[index] * 256));
+ uint32_t duty = cie_lightness(rescale_limit_val(scale_backlight(breathing_table[index] * 256)));
 
  chSysLockFromISR();
  pwmEnableChannelI(pwmp, BACKLIGHT_PWM_CHANNEL - 1, PWM_FRACTION_TO_WIDTH(&BACKLIGHT_PWM_DRIVER, 0xFFFF, duty));