MicroZed Chronicles リスト http://adiuvoengineering.com/?page_id=285
@ Adam Taylor blog
https://forums.xilinx.com/t5/Xcell-Daily-Blog/Adam-Taylor-s-MicroZed-Chronicles-Part-32-Driving-Adafruit-RGB/ba-p/457596
NeoPixels have no clock line. They use a unique self-clocking, non-return-to-zero (NRZ) waveform to specify the bit values, as shown below:
図についてはblog参照
The waveform’s bit period and duty cycle both change depending on whether the bit value represented is a 1 or 0. The timings are: T0H = 0.35μsec, T0L = 0.8μsec, T1H = 0.7μsec, and T1L = 0.6μsec. All timing values have a tolerance of ± 150nsec. These times give slightly different durations for a Low bit (1.15μsec) compared to a High bit (1.3μsec). We will analyze this serial communications scheme in much more detail when we write the software driver in a future blog.
If a NeoPixel does not start receiving another word within 50μsec after receiving all 24 data bits in a data word, it loads the received 24-bit word into an internal register and lights its three LEDs using that 24-bit value. However, if the NeoPixel does receive another 24-bit word within the 50μsec timeout period, it retransmits the previously received word on its Dout port instead of using it internally. This mechanism allows you to use one serial signal line to control a large number of pixels in a very simple manner.
最後の節の処理は電子工作で連結した基板通信に使えるかもしれないのでメモとして残す。