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Figure 70 Parameter Definitions in Cropping Window
VSLINECNT
HOFSCNT
CCNT
VLINECNT
It should be noted that only when the value of CCNT is a multiple of 4, can data
be transmitted through DMA.
JPEG format
Since JPEG is stored as data rather than frame or line, only when VSYNC is
used as the start signal and HSYNC is used as the data enable signal, can the
module receive JPEG images.
Only when the module captures a complete 32-bit word, can a DMA request be
generated. Therefore, when the end of the frame is detected, the received data
is less than 32 bits, and the remaining bits need to be stuffed with "0".
In addition, cropping function and embedded code synchronization mode cannot
be used by JPEG format.
FIFO
The module is provided with a FIFO controller, which realizes FIFO with 4-word
depth so as to manage the data transmission on AHB. If the transmission rate is
greater than the maximum rate that AHB can bear, the FIFO data will be
overwritten because there is no overflow protection.
When the synchronization signal is wrong or FIFO overflows, FIFO will be reset
and DCI will wait for the new data frame.
Data format
The module supports three kinds of data formats:
Monochrome format
YCbCr format