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AT32F435/437
Series Reference Manual
2022.11.11
Page 647
Rev 2.03
output data FIFO becomes full for the reason that the DMA is unable to capture data in time and transfer
them to memory unit, in this case, the captured data will be discarded, and an output data overrun error
interrupt is generated. If the CAP is not enabled, both OVRES and OVRIS bits have no effect.
Embedded synchronization error
When the ESEES and ESEIS bits (CAP enabled, and SM=1) are set, it indicates the error status of
embedded synchronization error. If it outputs an unexpected synchronization code, the decoder discards
the current synchronization, and re-decode the subsequent data. In this case, the DVP stops data
capturing and generates an embedded synchronization error. If the CAP is not enabled, both ESEES
and ESEIS bits have no effect.
27.6 Functional overview
27.6.1 Frame rate control
The DVP interface can adjust the number of frame captured every second with the frame rate control
feature. The frame rate control feature applies to continuous capture mode (CFM=0). It consists of a
basic frame rate control and progressive frame rate control.
Figure 27-9 Block diagram of frame rate control feature
BFRC
or
EFRC
Basic frame rate control
Capture a frame per
two frames or per two four frames, which is programmable by the BFRC bit in
the DVP_CTR register.
Enhanced frame rate control
To acquire a fine frame rate, the advanced frame rate control is a choice. To enable this feature, set
BFRC=0, and set the
EFRCE bit in the DVP_ACTRL register, the DVP can adjust the number of
frames through the EFRCSF and EFRCTF bits in the DVP_FRF register, based on the following
formula:
𝑇𝑎𝑟𝑔𝑒𝑡 𝑓𝑟𝑎𝑚𝑒 𝑟𝑎𝑡𝑒
=
𝐸𝐹𝑅𝐶𝑇𝐹
𝐸𝐹𝑅𝐶𝑆𝐹
× 𝑂𝑟𝑖𝑔𝑖𝑛𝑎𝑙 𝑓𝑟𝑎𝑚𝑒 𝑟𝑎𝑡𝑒
Note: When the advanced frame rate control feature is used, the EFRCSF and EFRCTF bits must not
be set to zero, and the EFRCTF must not be greater than the EFRCSF bit.
27.6.2 Crop window
The crop window feature can be used to retain the desired data area and discard the remaining area.
When the CRP bit is set in the DVP_CTRL register, the DVP follows the configurations of the
DVP_CWST and DVP_CWSZ registers to perform crop feature.