Hardware Reference
In-Depth Information
Figure 3-7. FLORA RGB NeoPixels
These pixels have full 24-bit color ability with PWM (brightness;
see the following sidebar) taken care of by the controller chip.
Since the LED is so bright, you need less current/power to get
the effects you want. The driver is constant current, so it's OK if
your battery power changes or fluctuates a little. You can power
FLORA NeoPixels with as little as 3.5V, though they will be dim-
mer than with 5-9V.
Understanding PWM
Pulse Width Modulation, or PWM, is a clever way to control the
amount of power delivered to electrical devices. Imagine flip-
ping a light switch on and off really quickly. If you do this fast
enough—so fast that you can't perceive the fact that it's switch-
ing on and off rapidly—the light in the room will be on roughly
half the time, and the room will be darker than if you just left the
light on. This is what is happening with NeoPixels. You are con-
trolling the power sent to the LEDs with PWM. The longer you
leave the power on instead of of , the brighter the LED will be.
Each pixel draws as much as 55 mA (all three RGB LEDs on for
full-brightness white). In theory, FLORA can drive up to 500 pix-
els at 30 frames per second (it will run out of RAM if you try to
drive more). However, after about 10 pixels (or if the distance
 
Search WWH ::




Custom Search