The APA102 is a RGB LED with integrated controller. LEDs can be
daisy-chained and use SPI for communication. The SPI port is
configured via Device Tree.
Tested on the Adafruit Trinket M0.
Signed-off-by: Michael Hope <mlhx@google.com>
Introducing CMake is an important step in a larger effort to make
Zephyr easy to use for application developers working on different
platforms with different development environment needs.
Simplified, this change retains Kconfig as-is, and replaces all
Makefiles with CMakeLists.txt. The DSL-like Make language that KBuild
offers is replaced by a set of CMake extentions. These extentions have
either provided simple one-to-one translations of KBuild features or
introduced new concepts that replace KBuild concepts.
This is a breaking change for existing test infrastructure and build
scripts that are maintained out-of-tree. But for FW itself, no porting
should be necessary.
For users that just want to continue their work with minimal
disruption the following should suffice:
Install CMake 3.8.2+
Port any out-of-tree Makefiles to CMake.
Learn the absolute minimum about the new command line interface:
$ cd samples/hello_world
$ mkdir build && cd build
$ cmake -DBOARD=nrf52_pca10040 ..
$ cd build
$ make
PR: zephyrproject-rtos#4692
docs: http://docs.zephyrproject.org/getting_started/getting_started.html
Signed-off-by: Sebastian Boe <sebastian.boe@nordicsemi.no>
The WS2812 LED driver IC has a one-wire interface which encodes bit
values as pulse widths.
The ICs themselves are basically shift registers. Roughly speaking, a
"short" pulse shifts in a zero bit, a "long" pulse shifts in a one
bit, and an inter-pulse gap exceeding a reset time threshold causes a
pixel to latch the shifted-in color values. Each chip has an output
pin for daisy chaining. Refer to the chip datsheets and comments in
Kconfig.ws2812 for more details.
To meet timing without hogging the core, this driver generates pulses
using SPI. To work, this requires the MOSI line to stay low between
SPI frames, and for inter-frame delays to be less than the reset pulse
time.
There are other ways do it (PWM + DMA on some SoCs, GPIO bit-banging
if no other tasks need the core), but this is a reasonably
general-purpose implementation.
Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>
LPD880x (e.g. LPD8803, LPD8806) devices are LED driver ICs which can
be controlled via a reduced SPI interface (clock and data only), and
support daisy chaining.
Add an led_strip driver for these devices.
Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>
This API covers drivers for strips, or strings, of individually
addressable LEDs. Both RGB and grayscale LED strip drivers can be
implemented within these APIs.
The API only provides for updating the entire strip, since not all
strips support updating individual LEDs without affecting the others.
Subsequent patches will add individual driver support.
Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>
