Image sensor interface (isi), 1 overview – Rainbow Electronics AT91CAP9S250A User Manual
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6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
45. Image Sensor Interface (ISI)
45.1
Overview
The Image Sensor Interface (ISI) connects a CMOS-type image sensor to the processor and
provides image capture in various formats. It does data conversion, if necessary, before the stor-
age in memory through DMA.
The ISI supports color CMOS image sensor and grayscale image sensors with a reduced set of
functionalities.
In grayscale mode, the data stream is stored in memory without any processing and so is not
compatible with the LCD controller.
Internal FIFOs on the preview and codec paths are used to store the incoming data. The RGB
output on the preview path is compatible with the LCD controller. This module outputs the data
in RGB format (LCD compatible) and has scaling capabilities to make it compliant to the LCD
display resolution (See
Several input formats such as preprocessed RGB or YCbCr are supported through the data bus
interface.
It supports two modes of synchronization:
1.
The hardware with ISI_VSYNC and ISI_HSYNC signals
2.
The International Telecommunication Union Recommendation ITU-R BT.656-4 Start-of-
Active-Video (SAV) and End-of-Active-Video (EAV) synchronization sequence.
Using EAV/SAV for synchronization reduces the pin count (ISI_VSYNC, ISI_HSYNC not used).
The polarity of the synchronization pulse is programmable to comply with the sensor signals.
Figure 45-1. ISI Connection Example
Table 45-1.
I/O Description
Signal
Dir
Description
ISI_VSYNC
IN
Vertical Synchronization
ISI_HSYNC
IN
Horizontal Synchronization
ISI_DATA[11..0]
IN
Sensor Pixel Data
ISI_MCK
OUT
Master Clock Provided to the Image Sensor
ISI_PCK
IN
Pixel Clock Provided by the Image Sensor
Image Sensor
Image Sensor Interface
data[11..0]
ISI_DATA[11..0]
CLK
ISI_MCK
PCLK
ISI_PCK
VSYNC
HSYNC
ISI_VSYNC
ISI_HSYNC