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Figure 4-1-6 Steering gear pin definition
4.2 RGB WS2812B Experiment
4.2.1 RGB WS2812B Description
The WS2812B is 3 output channels special for LED driver circuit. Its internal includes intelligent digital
port data latch and signal reshaping amplification drive circuit. Also includes a precision internal oscillator
and a 12V voltage programmable constant current output drive. In the purpose of reduce power supply ripple,
the 3 output channels designed to delay turn-on function.
Unlike the traditional RGB,
WS281B
is integrated with a WS281B LED drive control special chip,
which requires a single signal line to control a LED lamp or multiple LED modules. Features as below:
Output port compression 12V.
Built-in voltage-regulator tube, only a resistance needed to add to IC VDD feet when under 24V power
supply.
256 Gray-scale adjustable and scan frequency is more than 2KHz.
Built in signal reshaping circuit, to ensure waveform distortion do not accumulate after wave reshaping
to the next driver
Built-in electrify reset circuit and power-down reset circuit.
Cascading port transmission signal by single line
Any two point the distance less than 5 Meters transmission signal without any increase circuit.
When the refresh rate is 30fps, the cascade number is at least 1024 pixels.
Send data at speed of 800Kbps.
For more parameters of WS2812,please check the file in
CD:“Document
\WS281B
.pdf”
4.2.2 RGB WS281B working principle
IC uses single NZR communication mode. After the chip power-on reset, the DIN port receive data
from controlle,the first IC collect initial 24bit data then sent to the internal data latch,the other data which
reshaping by the internal signal reshaping amplification circuit sent to the next cascade IC through the DO
port. After transmission for each chip, the signal to reduce 24bit. IC adopt auto reshaping transmit
technology,making the chip cascade number is not limited the signal transmission,only depend on the speed
of signal transmission.
The data latch of IC depend on the received 24bit data produce different duty ratio signal at
OUTR,OUTG,OUTB port.All chip synchronous send the received data to each segment when the DIN port
input a reset signal. It will receive new data again after the reset signal finished. Before a new reset signal
