Understanding the APA102 “Superled”

Tim writes:

To investigate the functionality of the AP102, I connected an ATtiny85 to the clock and data input lines and used a logic analyzer to probe both the input and output lines. The microcontroller was programmed to output various bit patterns as described below.
I focused my investigation on four areas:

1. Behavior of the “Start Frame”
2. Function of the “111” bits in the “LED Frame”
3. How data is forwarded to the next device
4. Impact of the “End Frame”

Details can be found on Tim’s blog.