Ok, so it looks like you have to continuously send data to these parts.
One way to do that is with SPI.transfer( )s
Set the SPI divisor to 1/16 for 1 Mbps data rate, and send out the three bytes of data
void loop(){
currentmicros = micros(); // time elemets are all unsigned long
if ( (currentmicros-previousmicros) >= interval) // interval at 20 ? (microseconds) = 320 clock cycles
{
previousmicros = previousmicros + interval; // set up next time period
SPI.transfer(green_byte); // or whatever order is needed
SPI.transfer(red_byte);
SPI.transfer(blue_byte);
}
// update color codes as needed
}