255 lines
8.4 KiB
Plaintext
255 lines
8.4 KiB
Plaintext
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ZC0301 Image Processor and Control Chip
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Driver for Linux
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=======================================
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- Documentation -
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Index
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=====
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1. Copyright
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2. Disclaimer
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3. License
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4. Overview and features
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5. Module dependencies
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6. Module loading
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7. Module parameters
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8. Supported devices
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9. Notes for V4L2 application developers
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10. Contact information
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11. Credits
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1. Copyright
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============
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Copyright (C) 2006 by Luca Risolia <luca.risolia@studio.unibo.it>
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2. Disclaimer
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=============
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This software is not developed or sponsored by Z-Star Microelectronics Corp.
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Trademarks are property of their respective owner.
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3. License
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==========
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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4. Overview and features
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========================
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This driver supports the video interface of the devices mounting the ZC0301
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Image Processor and Control Chip.
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The driver relies on the Video4Linux2 and USB core modules. It has been
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designed to run properly on SMP systems as well.
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The latest version of the ZC0301 driver can be found at the following URL:
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http://www.linux-projects.org/
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Some of the features of the driver are:
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- full compliance with the Video4Linux2 API (see also "Notes for V4L2
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application developers" paragraph);
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- available mmap or read/poll methods for video streaming through isochronous
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data transfers;
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- automatic detection of image sensor;
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- video format is standard JPEG;
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- dynamic driver control thanks to various module parameters (see "Module
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parameters" paragraph);
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- up to 64 cameras can be handled at the same time; they can be connected and
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disconnected from the host many times without turning off the computer, if
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the system supports hotplugging;
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5. Module dependencies
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======================
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For it to work properly, the driver needs kernel support for Video4Linux and
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USB.
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The following options of the kernel configuration file must be enabled and
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corresponding modules must be compiled:
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# Multimedia devices
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#
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CONFIG_VIDEO_DEV=m
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# USB support
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#
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CONFIG_USB=m
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In addition, depending on the hardware being used, the modules below are
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necessary:
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# USB Host Controller Drivers
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#
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CONFIG_USB_EHCI_HCD=m
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CONFIG_USB_UHCI_HCD=m
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CONFIG_USB_OHCI_HCD=m
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The ZC0301 controller also provides a built-in microphone interface. It is
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supported by the USB Audio driver thanks to the ALSA API:
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# Sound
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#
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CONFIG_SOUND=y
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# Advanced Linux Sound Architecture
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#
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CONFIG_SND=m
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# USB devices
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#
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CONFIG_SND_USB_AUDIO=m
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And finally:
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# USB Multimedia devices
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#
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CONFIG_USB_ZC0301=m
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6. Module loading
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=================
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To use the driver, it is necessary to load the "zc0301" module into memory
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after every other module required: "videodev", "usbcore" and, depending on
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the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd".
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Loading can be done as shown below:
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[root@localhost home]# modprobe zc0301
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At this point the devices should be recognized. You can invoke "dmesg" to
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analyze kernel messages and verify that the loading process has gone well:
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[user@localhost home]$ dmesg
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7. Module parameters
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====================
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Module parameters are listed below:
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-------------------------------------------------------------------------------
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Name: video_nr
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Type: short array (min = 0, max = 64)
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Syntax: <-1|n[,...]>
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Description: Specify V4L2 minor mode number:
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-1 = use next available
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n = use minor number n
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You can specify up to 64 cameras this way.
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For example:
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video_nr=-1,2,-1 would assign minor number 2 to the second
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registered camera and use auto for the first one and for every
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other camera.
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Default: -1
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-------------------------------------------------------------------------------
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Name: force_munmap
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Type: bool array (min = 0, max = 64)
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Syntax: <0|1[,...]>
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Description: Force the application to unmap previously mapped buffer memory
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before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not
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all the applications support this feature. This parameter is
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specific for each detected camera.
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0 = do not force memory unmapping
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1 = force memory unmapping (save memory)
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Default: 0
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-------------------------------------------------------------------------------
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Name: frame_timeout
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Type: uint array (min = 0, max = 64)
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Syntax: <n[,...]>
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Description: Timeout for a video frame in seconds. This parameter is
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specific for each detected camera. This parameter can be
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changed at runtime thanks to the /sys filesystem interface.
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Default: 2
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-------------------------------------------------------------------------------
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Name: debug
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Type: ushort
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Syntax: <n>
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Description: Debugging information level, from 0 to 3:
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0 = none (use carefully)
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1 = critical errors
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2 = significant informations
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3 = more verbose messages
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Level 3 is useful for testing only, when only one device
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is used at the same time. It also shows some more informations
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about the hardware being detected. This module parameter can be
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changed at runtime thanks to the /sys filesystem interface.
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Default: 2
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-------------------------------------------------------------------------------
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8. Supported devices
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====================
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None of the names of the companies as well as their products will be mentioned
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here. They have never collaborated with the author, so no advertising.
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From the point of view of a driver, what unambiguously identify a device are
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its vendor and product USB identifiers. Below is a list of known identifiers of
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devices mounting the ZC0301 Image Processor and Control Chips:
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Vendor ID Product ID
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--------- ----------
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0x041e 0x4017
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0x041e 0x401c
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0x041e 0x401e
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0x041e 0x4034
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0x041e 0x4035
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0x046d 0x08ae
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0x0ac8 0x0301
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0x10fd 0x8050
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The list above does not imply that all those devices work with this driver: up
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until now only the ones that mount the following image sensors are supported;
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kernel messages will always tell you whether this is the case:
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Model Manufacturer
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----- ------------
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PAS202BCB PixArt Imaging, Inc.
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9. Notes for V4L2 application developers
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========================================
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This driver follows the V4L2 API specifications. In particular, it enforces two
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rules:
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- exactly one I/O method, either "mmap" or "read", is associated with each
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file descriptor. Once it is selected, the application must close and reopen the
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device to switch to the other I/O method;
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- although it is not mandatory, previously mapped buffer memory should always
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be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's.
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The same number of buffers as before will be allocated again to match the size
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of the new video frames, so you have to map the buffers again before any I/O
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attempts on them.
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10. Contact information
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=======================
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The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>.
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GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is
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'FCE635A4'; the public 1024-bit key should be available at any keyserver;
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the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'.
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11. Credits
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===========
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- Informations about the chip internals needed to enable the I2C protocol have
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been taken from the documentation of the ZC030x Video4Linux1 driver written
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by Andrew Birkett <andy@nobugs.org>;
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- The initialization values of the ZC0301 controller connected to the PAS202BCB
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image sensor have been taken from the SPCA5XX driver maintained by
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Michel Xhaard <mxhaard@magic.fr>.
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