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| author | William Chang <william@factual.com> | 2019-07-13 10:18:33 -0700 |
|---|---|---|
| committer | William Chang <william@factual.com> | 2019-07-13 10:18:33 -0700 |
| commit | 71493b2f9bbd5f3d18373c518fa14ccafcbf48fc (patch) | |
| tree | 3bb3e5e496621535611e087720aa5c4d7a533e5e /docs/feature_backlight.md | |
| parent | 86ad4988fe7ff64916127509d84f44c56fa097aa (diff) | |
| parent | da1f05fbc19477c05c0c01bb07fabfaf1ece9d54 (diff) | |
Merge branch 'master' of https://github.com/qmk/qmk_firmware
Diffstat (limited to 'docs/feature_backlight.md')
| -rw-r--r-- | docs/feature_backlight.md | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/docs/feature_backlight.md b/docs/feature_backlight.md index 048d75390d..b06db89e4d 100644 --- a/docs/feature_backlight.md +++ b/docs/feature_backlight.md @@ -34,13 +34,14 @@ Hardware PWM is only supported on certain pins of the MCU, so if the backlightin Hardware PWM is supported according to the following table: -| Backlight Pin | Hardware timer | -|---------------|----------------| -|`B5` | Timer 1 | -|`B6` | Timer 1 | -|`B7` | Timer 1 | -|`C6` | Timer 3 | -| other | Software PWM | +| Backlight Pin | Hardware timer | +|---------------|-------------------------| +|`B5` | Timer 1 | +|`B6` | Timer 1 | +|`B7` | Timer 1 | +|`C6` | Timer 3 | +|`D4` | Timer 1 (ATmega32A only)| +| other | Software PWM | The [audio feature](feature_audio.md) also uses hardware timers. Please refer to the following table to know what hardware timer the software PWM will use depending on the audio configuration: @@ -63,11 +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 |