Got a sweet 32 light strip of 3 color LEDs from Sparkfun [url]http://www.sparkfun.com/products/10312[/url] . A sample sketch was provided for an arduino, which ran with (literally) a blindingly fast refresh rate (duino pro, 5v, 16mhtz). I ported the code to NETMF, ran it on a Domino, and discovered the refresh rate of the strip slowed down considerably. This is some straight up bit banging, and I’m wondering if it is better done in RLP?
using System;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using GHIElectronics.NETMF.FEZ;
namespace RgbStrip
{
public class Program
{
const int LEN = 32; // 32 LEDs on this strip.
const bool HIGH = true; // I like using HIGH/LOW
const bool LOW = false; // for bit bangin' like this.
static long[] strip; // strip color data array
static OutputPort sdi; // digital pin 2
static OutputPort cki; // digital pin 3
public static void Main()
{
strip_colors = new long[LEN];
sdi = new OutputPort((Cpu.Pin)FEZ_Pin.Digital.Di2, LOW);
cki = new OutputPort((Cpu.Pin)FEZ_Pin.Digital.Di3, LOW);
// spit out some bytes
loop();
}
// Push out increasingly bright primary colors
private static void loop()
{
/////////////////////////////////////////////////
// Saturation must be byte sized, 0-255.
// Outside this range, strange things happen...
/////////////////////////////////////////////////
int lHue = 120; // low sat value
int hHue = 160; // high sat value
while(true)
{
for (int i = lHue; i < hHue; i++)
addColor(i, 0, 0);
for (int i = lHue; i < hHue; i++)
addColor(0, i, 0);
for (int i = lHue; i < hHue; i++)
addColor(0, 0, i);
}
}
// Add one color to the strip
private static void addColor (int R, int G, int B)
{
// shift all existing colors
for (int x = (LEN - 1); x > 0; x--)
strip[x] = strip[x - 1];
////////////////////////////
// create a new RGB color
////////////////////////////
long new_color = R; // red
new_color <<= 8; // byte shift
new_color |= G; // green
new_color <<= 8; // shift again
new_color |= B; // blue
strip[0] = new_color; // add to strip
postFrame(); // push data
}
// Pushes out current strip color array.
// Each LED requires 24 bits of data.
// Once the bits have been delivered,
// the IC immediately relays these bits to its neighbor.
// Pulling the clock low for 500us or more causes the
// IC to post the data.
private static void postFrame ()
{
for(int i=0;i<LEN;i++)
{
for(byte bit = 23 ; bit != 255 ; bit--)
{
cki.Write(LOW); // only change data when clock is low
long mask = 1 << bit;
if ((strip[i] & mask) > 0)
sdi.Write(HIGH);
else
sdi.Write(LOW);
cki.Write(HIGH); // data is latched when clock goes high
}
}
cki.Write(LOW); // pull clock low to put strip into reset/post mode
//Thread.Sleep(1); // required delay. Note, this was not needed here (slow enough already).
}
}
}
