jasonluther / pi-rgb Goto Github PK

Use wiringPi to control a common-anode RGB LED from the GPIO pins.

git clone git://git.drogon.net/wiringPi cd wiringPi ./build

Each color is actually switched by an NPN transistor so that you can drive the LED with +5v and more current than the GPIO pins can handle. Use a resource like http://www.kpsec.freeuk.com/trancirc.htm#ic to calculate the resistor value.

Only one GPIO pin supports hardware PWM, so we get to use this sweet software PWM library.

rgb.c will run all the time. Its job is to manage the GPIO pins based on the contents of a command structure that's set using mmap() for IPC.

To set the command (color and mode), see write_rgbcmd.c. It uses mmap() to choose the mode (on, off, blink, rainbow, and random) and the color for the on/blink modes.

We want to have a simple way to set the mode and color:

http://pi/rgbcmd/on/ff0012
http://pi/rgbcmd/blink/ff0000
http://pi/rgbcmd/off
http://pi/rgbcmd/rainbow
http://pi/rgbcmd/random

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

This work is placed into the public domain.