EE181| Application Note
Engineer To Engineer Note
EE-181
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Technical Notes on using Analog Devices' DSP components and development tools
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Interfacing the ADSP-BF535 Blackfin Processor to Single-CHIP CIF Digital Camera "OV6630" over the External Memory Bus
Contributed by Thorsten Lorenzen April 17, 2003
1 Introduction
The purpose of this note is to describe how to hook up video devices like a CIF (Common Interface Format) Single Chip Digital Camera to the external bus of the ADSP-BF535 Blackfin Processor. Because of its architecture and video processing capabilities, Blackfin Processors will interface with video devices. The ADSP-BF535 as the first part of the Blackfin family is not equipped with a standard interface that glueless interact with video devices. This note is dedicated to show how the Asynchronous Interface can be used to receive video in CIF sizes.
and must be linked to the ADSP-BF535 for data transfers. Additionally, some pins are required for device control and configuration purposes. The pin HREF asserted (polarity can be chosen) indicates active video pixels (image data).
2 Output Format of the OV6630
The OV6630 is a CMOS Image sensor provided as a single chip video/imaging camera device designed to provide a high level functionality in a single, small-footprint package. For more details about the functionality it is referred to the internet address below. In order to explain the way been accessed by the ADSP-BF535 Processor see the schematic of the required output pins in figure 2.1. The datasheet for the OV6630 can be found at www.ovt.com As it can be seen in figure 2.1 the pins Y[7:0] and UV[7:0] are required to transfer data. The PCLK represents the clock aligned to the data. Each raising edge of the PCLK will indicate valid data on the bus. These pins are necessary
Figure 2.1
Because of the programmable sensor size as it is discussed below HREF provides a way to distinguish between active video pixels and blank data. The blank data of the modified senor field will also be transferred and is represented by hex "10" on Y[7:0] and hex "80" UV[7:0]. Figure 2.2 shows a transfer of one pixel, blanking and HREF indicating an active pixel. Due to the configuration the sensor is set to output over a 16 -bit bus in this note. One pixel exists of one byte of luminance and one byte of
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