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authorfauxpark <fauxpark@gmail.com>2019-06-20 15:33:39 +1000
committerDrashna Jaelre <drashna@live.com>2019-06-19 22:33:39 -0700
commit317b8095647e208a7ac1ecf6b110051ca46553a8 (patch)
tree724a2dc9d0b5071999f25400c453ca061e1c0827 /docs/feature_backlight.md
parent67e0c951afee99ac1e1e96354655296457f57b78 (diff)
Fix breathing always on for soft PWM (#5983)
* Fix breathing always on for soft PWM * Remove reference to hardware PWM pins in BACKLIGHT_BREATHING description Now, breathing will only be unsupported when Timers 1 and 3 are both used by Audio * Document BACKLIGHT_ON_STATE and its purpose
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1 files changed, 8 insertions, 2 deletions
diff --git a/docs/feature_backlight.md b/docs/feature_backlight.md
index 5a21a67901..b06db89e4d 100644
--- a/docs/feature_backlight.md
+++ b/docs/feature_backlight.md
@@ -64,11 +64,17 @@ To change the behaviour of the backlighting, `#define` these in your `config.h`:
|Define |Default |Description |
|---------------------|-------------|-------------------------------------------------------------------------------------------------------------|
|`BACKLIGHT_PIN` |`B7` |The pin that controls the LEDs. Unless you are designing your own keyboard, you shouldn't need to change this|
-|`BACKLIGHT_PINS` |*Not defined*|experimental: see below for more information|
+|`BACKLIGHT_PINS` |*Not defined*|experimental: see below for more information |
|`BACKLIGHT_LEVELS` |`3` |The number of brightness levels (maximum 15 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 |
+|`BACKLIGHT_BREATHING`|*Not defined*|Enable backlight breathing, if supported |
|`BREATHING_PERIOD` |`6` |The length of one backlight "breath" in seconds |
+|`BACKLIGHT_ON_STATE` |`0` |The state of the backlight pin when the backlight is "on" - `1` for high, `0` for low |
+
+## Backlight On State
+
+Most backlight circuits are driven by an N-channel MOSFET or NPN transistor. This means that to turn the transistor *on* and light the LEDs, you must drive the backlight pin, connected to the gate or base, *low*.
+Sometimes, however, a P-channel MOSFET, or a PNP transistor is used. In this case you must `#define BACKLIGHT_ON_STATE 1`, so that when the transistor is on, the pin is driven *high* instead.
## Multiple backlight pins