Andrewh, the strips I used were from GL LEDs in China, and used a chip whose name temporarily escapes me; it was basically an SPI part with a 24-bit shift register- eight bits for each of R, G and B. Sending 25 consecutive 1-bits would latch the shift register contents into the PWM engine. Essentially it was totally addressable, unlike the HL1606, with the only restrictions being that it required a constant clock waveform (there was no on-die oscillator, but you could just shift zeroes and it would not affect the PWM) and you could not send the (255, 255, 255) without messing up the framing- if the preceding bit was a 1, it would latch the current contents of the shift register, which was not what I wanted. So, technically it wasn't *quite* 24-bit, since there was one code you could not safely send. Still capable of 16.7 million colours though.