pim/mongoose-touch
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Update README with the new backlight implementation details

Browse Source
This commit is contained in:
Pim van Pelt
2017-11-28 15:42:52 +01:00
parent 7041526a39
commit 1ef7195728
1 changed files with 7 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
README.md
View File

@ -169,18 +169,17 @@ added time `widget`.
The Featherwing has a PWM based backlight. The implementaion in The Featherwing has a PWM based backlight. The implementaion in
`src/backlight.c` shows a way to dim the screen when it is not in use. `src/backlight.c` shows a way to dim the screen when it is not in use.
The way this works, is by means of `backlight_keepalive()` which sets the The way this works, is by means of `backlight_keepalive()` which sets the
backlight on, and installs a timer (by default for 10 seconds). Each time backlight on, and updates `backlight_last_keepalive`. A timer checks if
the user touches the screen, the timer is re-initialized. If the user does the last keepalive call hasn't been too long ago, and if it was, it initiates
not touch the screen, the timer invokes the callback `backlight_keepalive_cb()` a screen dimmer by setting a new target duty cycle and time to get to that
which will set turn the screen off: it will install a target duty cycle and target (usually 1000ms). Then it'll start a repeating a 20ms timer that dims
time to get to that target (usually 1000ms). Then it'll start a repeating the backlight until the target it reached, after which it deinstalls itself.
a 10ms timer that dims the backlight until the target it reached, after See `backlight_fader_cb()` for details. Very slick!
which it deinstalls itself. See `backlight_fader_cb()` for details. Very slick!
If the screen is off, `backlight_active()` will return false. The main If the screen is off, `backlight_active()` will return false. The main
`touch_handler()` (the one that gets interrupts from the STMPE610), will `touch_handler()` (the one that gets interrupts from the STMPE610), will
ignore the first `TOUCH_DOWN` and `TOUCH_UP` events in that case, but it ignore the first `TOUCH_DOWN` and `TOUCH_UP` events in that case, but it
will wake up the screen again by setting the backlight back on. will wake up the screen again by calling `backlight_keepalive().`
### Other tricks ### Other tricks