Rainbow Electronics AT91CAP9S250A - Manual (Page 912)

912
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
45.2 Block Diagram
Figure 45-2. Image Sensor Interface Block Diagram
45.3 Functional Description
The Image Sensor Interface (ISI) supports direct connection to the ITU-R BT. 601/656 8-bit
mode compliant sensors and up to 12-bit grayscale sensors. It receives the image data stream
from the image sensor on the 12-bit data bus.
This module receives up to 12 bits for data, the horizontal and vertical synchronizations and the
pixel clock. The reduced pin count alternative for synchronization is supported for sensors that
embed SAV (start of active video) and EAV (end of active video) delimiters in the data stream.
The Image Sensor Interface interrupt line is generally connected to the Advanced Interrupt Con-
troller and can trigger an interrupt at the beginning of each frame and at the end of a DMA frame
transfer. If the SAV/EAV synchronization is used, an interrupt can be triggered on each delimiter
event.
For 8-bit color sensors, the data stream received can be in several possible formats: YCbCr
4:2:2, RGB 8:8:8, RGB 5:6:5 and may be processed before the storage in memory. The data
stream may be sent on both preview path and codec path if the bit CODEC_ON in the ISI_CR1
is one. To optimize the bandwidth, the codec path should be enabled only when a capture is
required.
In grayscale mode, the input data stream is stored in memory without any processing. The 12-bit
data, which represent the grayscale level for the pixel, is stored in memory one or two pixels per
word, depending on the GS_MODE bit in the ISI_CR2 register. The codec datapath is not avail-
able when grayscale image is selected.
A frame rate counter allows users to capture all frames or 1 out of every 2 to 8 frames.
Timing Signals
Interface
CCIR-656
Embedded Timing
Decoder(SAV/EAV)
Pixel Sampling
Module
Clipping + Color
Conversion
YCC to RGB
2-D Image
Scaler
Pixel
Formatter
Rx Direct
Display
FIFO
Core
Video
Arbiter
Camera
AHB
Master
Interface
APB
Interface Camera
Interrupt
Controller
Config
Registers
Clipping + Color
Conversion
RGB to YCC
Rx Direct
Capture
FIFO
Scatter
Mode
Support
Packed
Formatter
Frame Rate
YCbCr 4:2:2
8:8:8
5:6:5
RGB
CMOS
sensor
Pixel input
up to 12 bit
Hsync/Len
Vsync/Fen
CMOS
sensor
pixel clock
input
Pixel
Clock Domain AHB
Clock Domain
APB
Clock Domain
From
Rx buffers
Camera
Interrupt Request Line
codec_on
AHB b
u
s
APB b
u
s