Virtual
space 2
Physical
space 2
(SDRAM)
The camera
ISP writes a full
frame to the
virtual space
The circular buffer
maps virtual
addressees to
physical addresses
in SDRAM. Data is
stored in SDRAM
An other module uses
data stored in SDRAM. It
informs the CBUFF
module when it is done
with a physical buffer
Camera
ISP
JPEG
CODEC
Virtual
space1
Physical
space 1
(SDRAM)
SW
preprocessing
Data is processed by
SW and stored in
SDRAM. If informs
the circular buffer
when a buffer is filled
ISP reads a full
frame from virtual
space 1. Addresses
are remapped into
the physical space
by the circular buffer
ISP may be
stalled to wait
for the CODEC
or the SW
preprocessing
step
camisp-166
Virtual
space
Physical space
(SDRAM)
The camera
ISP writes a full
frame to the
virtual space
The circular buffer
maps virtual
addresses to
physical addresses
in SDRAM. Data is
stored in SDRAM,
but not
necessarily
contiguous
An other module uses
data stored in SDRAM. It
informs the CBUFF
module when it is done
with a physical buffer and
it must be able to manage
fragmentation.
Camera ISP
JPEG
CODEC
camisp-409
Public Version
Camera ISP Functional Description
www.ti.com
Figure 6-102. Camera ISP Circular Buffer Extended Slice Buffer Example
The camera ISP prefetches data and buffers it in the SBL. The CSI1/CCP2B flexible input pre-buffers up
to 1K byte of data. In other words, the stall control for the CSI1/CCP2B interconnect read master port
must be triggered in advance. Otherwise, the camera ISP may prefetch invalid data.
The last moment when the CSI1/CCP2B interconnect read master port can be safely stalled is when the
physical read buffer still contains 1K byte of valid data. The camera ISP may or may not then read the
remaining data into its internal SBL buffer.
The minimum amount of buffered data depends on the circular buffer configuration and the used data
format.
When the processor filling the read buffer has no more data to write, the BCF feature must be disabled
(clear
[23:22] CBUFF0_BCF_CTRL or
[25:24] CBUFF1_BCF_CTRL) for the CBUFF
attached to the read data flow. This allows the camera ISP to prefetch the remaining data from the buffer
without stalling.
6.4.10.3.1.3 Camera ISP Circular Buffer Fragmentation Support
This mode is available only for context 0 and CBUFF0. The mapped physical space does not need to be
contiguous in memory.
NOTE:
Software must ensure proper configuration of the CBUFF0 specific fragmentation support
feature. Thus, the
register must be configured correctly even if functionality
was not initially required when data was accepted from ISP.
Software defines the location of each physical window using CBUFF0_ADDR0 through CBUFF0_ADDR15
(see
shows the fragmentation support.
Figure 6-103. Camera ISP Circular Buffer Fragmentation Support
provides the physical address of physical windows 0 to 15 for fragmentation functionality.
1238
Camera Image Signal Processor
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated
