Pixel Control Bus
Vision HDL Toolbox™ blocks use a nonvirtual bus data type,
control signals associated with serial pixel data. The bus contains 5
boolean signals indicating the validity of a pixel and its location
within a frame. You can easily connect the data and control output of one block to the input
of another, because Vision HDL Toolbox blocks use this bus for input and output. To convert an image into a pixel
stream and a
pixelcontrol bus, use the Frame to Pixels
For multipixel streaming, each vector of pixel values has one set of control signals.
Because the vector has only one
valid signal, the pixels in the vector
must be either all valid or all invalid. The
vStart signals apply to the pixel with the lowest index in the
vEnd signals apply to the pixel
with the highest index in the vector.
When you generate HDL code from a Simulink® model that uses this bus, you may need to declare an instance of
pixelcontrol bus in the base workspace. If you encounter the
Cannot resolve variable 'pixelcontrol' when you generate HDL
code in Simulink, use the
pixelcontrolbus function to create an
instance of the bus type. Then try generating HDL code again.
To avoid this issue, the Vision HDL Toolbox model template includes this line in the
Frame To Pixels | Pixels To Frame |