1 2 SN9C1xx PC Camera Controllers 3 Driver for Linux 4 ============================= 5 6 - Documentation - 7 8 9Index 10===== 111. Copyright 122. Disclaimer 133. License 144. Overview and features 155. Module dependencies 166. Module loading 177. Module parameters 188. Optional device control through "sysfs" 199. Supported devices 2010. Notes for V4L2 application developers 2111. Video frame formats 2212. Contact information 2313. Credits 24 25 261. Copyright 27============ 28Copyright (C) 2004-2007 by Luca Risolia <luca.risolia@studio.unibo.it> 29 30 312. Disclaimer 32============= 33SONiX is a trademark of SONiX Technology Company Limited, inc. 34This software is not sponsored or developed by SONiX. 35 36 373. License 38========== 39This program is free software; you can redistribute it and/or modify 40it under the terms of the GNU General Public License as published by 41the Free Software Foundation; either version 2 of the License, or 42(at your option) any later version. 43 44This program is distributed in the hope that it will be useful, 45but WITHOUT ANY WARRANTY; without even the implied warranty of 46MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 47GNU General Public License for more details. 48 49You should have received a copy of the GNU General Public License 50along with this program; if not, write to the Free Software 51Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 52 53 544. Overview and features 55======================== 56This driver attempts to support the video interface of the devices assembling 57the SONiX SN9C101, SN9C102, SN9C103, SN9C105 and SN9C120 PC Camera Controllers 58("SN9C1xx" from now on). 59 60The driver relies on the Video4Linux2 and USB core modules. It has been 61designed to run properly on SMP systems as well. 62 63The latest version of the SN9C1xx driver can be found at the following URL: 64http://www.linux-projects.org/ 65 66Some of the features of the driver are: 67 68- full compliance with the Video4Linux2 API (see also "Notes for V4L2 69 application developers" paragraph); 70- available mmap or read/poll methods for video streaming through isochronous 71 data transfers; 72- automatic detection of image sensor; 73- support for built-in microphone interface; 74- support for any window resolutions and optional panning within the maximum 75 pixel area of image sensor; 76- image downscaling with arbitrary scaling factors from 1, 2 and 4 in both 77 directions (see "Notes for V4L2 application developers" paragraph); 78- two different video formats for uncompressed or compressed data in low or 79 high compression quality (see also "Notes for V4L2 application developers" 80 and "Video frame formats" paragraphs); 81- full support for the capabilities of many of the possible image sensors that 82 can be connected to the SN9C1xx bridges, including, for instance, red, green, 83 blue and global gain adjustments and exposure (see "Supported devices" 84 paragraph for details); 85- use of default color settings for sunlight conditions; 86- dynamic I/O interface for both SN9C1xx and image sensor control and 87 monitoring (see "Optional device control through 'sysfs'" paragraph); 88- dynamic driver control thanks to various module parameters (see "Module 89 parameters" paragraph); 90- up to 64 cameras can be handled at the same time; they can be connected and 91 disconnected from the host many times without turning off the computer, if 92 the system supports hotplugging; 93- no known bugs. 94 95 965. Module dependencies 97====================== 98For it to work properly, the driver needs kernel support for Video4Linux and 99USB. 100 101The following options of the kernel configuration file must be enabled and 102corresponding modules must be compiled: 103 104 # Multimedia devices 105 # 106 CONFIG_VIDEO_DEV=m 107 108To enable advanced debugging functionality on the device through /sysfs: 109 110 # Multimedia devices 111 # 112 CONFIG_VIDEO_ADV_DEBUG=y 113 114 # USB support 115 # 116 CONFIG_USB=m 117 118In addition, depending on the hardware being used, the modules below are 119necessary: 120 121 # USB Host Controller Drivers 122 # 123 CONFIG_USB_EHCI_HCD=m 124 CONFIG_USB_UHCI_HCD=m 125 CONFIG_USB_OHCI_HCD=m 126 127The SN9C103, SN9c105 and SN9C120 controllers also provide a built-in microphone 128interface. It is supported by the USB Audio driver thanks to the ALSA API: 129 130 # Sound 131 # 132 CONFIG_SOUND=y 133 134 # Advanced Linux Sound Architecture 135 # 136 CONFIG_SND=m 137 138 # USB devices 139 # 140 CONFIG_SND_USB_AUDIO=m 141 142And finally: 143 144 # USB Multimedia devices 145 # 146 CONFIG_USB_SN9C102=m 147 148 1496. Module loading 150================= 151To use the driver, it is necessary to load the "sn9c102" module into memory 152after every other module required: "videodev", "v4l2_common", "compat_ioctl32", 153"usbcore" and, depending on the USB host controller you have, "ehci-hcd", 154"uhci-hcd" or "ohci-hcd". 155 156Loading can be done as shown below: 157 158 [root@localhost home]# modprobe sn9c102 159 160Note that the module is called "sn9c102" for historic reasons, althought it 161does not just support the SN9C102. 162 163At this point all the devices supported by the driver and connected to the USB 164ports should be recognized. You can invoke "dmesg" to analyze kernel messages 165and verify that the loading process has gone well: 166 167 [user@localhost home]$ dmesg 168 169or, to isolate all the kernel messages generated by the driver: 170 171 [user@localhost home]$ dmesg | grep sn9c102 172 173 1747. Module parameters 175==================== 176Module parameters are listed below: 177------------------------------------------------------------------------------- 178Name: video_nr 179Type: short array (min = 0, max = 64) 180Syntax: <-1|n[,...]> 181Description: Specify V4L2 minor mode number: 182 -1 = use next available 183 n = use minor number n 184 You can specify up to 64 cameras this way. 185 For example: 186 video_nr=-1,2,-1 would assign minor number 2 to the second 187 recognized camera and use auto for the first one and for every 188 other camera. 189Default: -1 190------------------------------------------------------------------------------- 191Name: force_munmap 192Type: bool array (min = 0, max = 64) 193Syntax: <0|1[,...]> 194Description: Force the application to unmap previously mapped buffer memory 195 before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not 196 all the applications support this feature. This parameter is 197 specific for each detected camera. 198 0 = do not force memory unmapping 199 1 = force memory unmapping (save memory) 200Default: 0 201------------------------------------------------------------------------------- 202Name: frame_timeout 203Type: uint array (min = 0, max = 64) 204Syntax: <0|n[,...]> 205Description: Timeout for a video frame in seconds before returning an I/O 206 error; 0 for infinity. This parameter is specific for each 207 detected camera and can be changed at runtime thanks to the 208 /sys filesystem interface. 209Default: 2 210------------------------------------------------------------------------------- 211Name: debug 212Type: ushort 213Syntax: <n> 214Description: Debugging information level, from 0 to 3: 215 0 = none (use carefully) 216 1 = critical errors 217 2 = significant informations 218 3 = more verbose messages 219 Level 3 is useful for testing only. It also shows some more 220 informations about the hardware being detected. 221 This parameter can be changed at runtime thanks to the /sys 222 filesystem interface. 223Default: 2 224------------------------------------------------------------------------------- 225 226 2278. Optional device control through "sysfs" [1] 228========================================== 229If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled, 230it is possible to read and write both the SN9C1xx and the image sensor 231registers by using the "sysfs" filesystem interface. 232 233Every time a supported device is recognized, a write-only file named "green" is 234created in the /sys/class/video4linux/videoX directory. You can set the green 235channel's gain by writing the desired value to it. The value may range from 0 236to 15 for the SN9C101 or SN9C102 bridges, from 0 to 127 for the SN9C103, 237SN9C105 and SN9C120 bridges. 238Similarly, only for the SN9C103, SN9C105 and SN9C120 controllers, blue and red 239gain control files are available in the same directory, for which accepted 240values may range from 0 to 127. 241 242There are other four entries in the directory above for each registered camera: 243"reg", "val", "i2c_reg" and "i2c_val". The first two files control the 244SN9C1xx bridge, while the other two control the sensor chip. "reg" and 245"i2c_reg" hold the values of the current register index where the following 246reading/writing operations are addressed at through "val" and "i2c_val". Their 247use is not intended for end-users. Note that "i2c_reg" and "i2c_val" will not 248be created if the sensor does not actually support the standard I2C protocol or 249its registers are not 8-bit long. Also, remember that you must be logged in as 250root before writing to them. 251 252As an example, suppose we were to want to read the value contained in the 253register number 1 of the sensor register table - which is usually the product 254identifier - of the camera registered as "/dev/video0": 255 256 [root@localhost #] cd /sys/class/video4linux/video0 257 [root@localhost #] echo 1 > i2c_reg 258 [root@localhost #] cat i2c_val 259 260Note that "cat" will fail if sensor registers cannot be read. 261 262Now let's set the green gain's register of the SN9C101 or SN9C102 chips to 2: 263 264 [root@localhost #] echo 0x11 > reg 265 [root@localhost #] echo 2 > val 266 267Note that the SN9C1xx always returns 0 when some of its registers are read. 268To avoid race conditions, all the I/O accesses to the above files are 269serialized. 270The sysfs interface also provides the "frame_header" entry, which exports the 271frame header of the most recent requested and captured video frame. The header 272is always 18-bytes long and is appended to every video frame by the SN9C1xx 273controllers. As an example, this additional information can be used by the user 274application for implementing auto-exposure features via software. 275 276The following table describes the frame header exported by the SN9C101 and 277SN9C102: 278 279Byte # Value or bits Description 280------ ------------- ----------- 2810x00 0xFF Frame synchronisation pattern 2820x01 0xFF Frame synchronisation pattern 2830x02 0x00 Frame synchronisation pattern 2840x03 0xC4 Frame synchronisation pattern 2850x04 0xC4 Frame synchronisation pattern 2860x05 0x96 Frame synchronisation pattern 2870x06 [3:0] Read channel gain control = (1+R_GAIN/8) 288 [7:4] Blue channel gain control = (1+B_GAIN/8) 2890x07 [ 0 ] Compression mode. 0=No compression, 1=Compression enabled 290 [2:1] Maximum scale factor for compression 291 [ 3 ] 1 = USB fifo(2K bytes) is full 292 [ 4 ] 1 = Digital gain is finish 293 [ 5 ] 1 = Exposure is finish 294 [7:6] Frame index 2950x08 [7:0] Y sum inside Auto-Exposure area (low-byte) 2960x09 [7:0] Y sum inside Auto-Exposure area (high-byte) 297 where Y sum = (R/4 + 5G/16 + B/8) / 32 2980x0A [7:0] Y sum outside Auto-Exposure area (low-byte) 2990x0B [7:0] Y sum outside Auto-Exposure area (high-byte) 300 where Y sum = (R/4 + 5G/16 + B/8) / 128 3010x0C 0xXX Not used 3020x0D 0xXX Not used 3030x0E 0xXX Not used 3040x0F 0xXX Not used 3050x10 0xXX Not used 3060x11 0xXX Not used 307 308The following table describes the frame header exported by the SN9C103: 309 310Byte # Value or bits Description 311------ ------------- ----------- 3120x00 0xFF Frame synchronisation pattern 3130x01 0xFF Frame synchronisation pattern 3140x02 0x00 Frame synchronisation pattern 3150x03 0xC4 Frame synchronisation pattern 3160x04 0xC4 Frame synchronisation pattern 3170x05 0x96 Frame synchronisation pattern 3180x06 [6:0] Read channel gain control = (1/2+R_GAIN/64) 3190x07 [6:0] Blue channel gain control = (1/2+B_GAIN/64) 320 [7:4] 3210x08 [ 0 ] Compression mode. 0=No compression, 1=Compression enabled 322 [2:1] Maximum scale factor for compression 323 [ 3 ] 1 = USB fifo(2K bytes) is full 324 [ 4 ] 1 = Digital gain is finish 325 [ 5 ] 1 = Exposure is finish 326 [7:6] Frame index 3270x09 [7:0] Y sum inside Auto-Exposure area (low-byte) 3280x0A [7:0] Y sum inside Auto-Exposure area (high-byte) 329 where Y sum = (R/4 + 5G/16 + B/8) / 32 3300x0B [7:0] Y sum outside Auto-Exposure area (low-byte) 3310x0C [7:0] Y sum outside Auto-Exposure area (high-byte) 332 where Y sum = (R/4 + 5G/16 + B/8) / 128 3330x0D [1:0] Audio frame number 334 [ 2 ] 1 = Audio is recording 3350x0E [7:0] Audio summation (low-byte) 3360x0F [7:0] Audio summation (high-byte) 3370x10 [7:0] Audio sample count 3380x11 [7:0] Audio peak data in audio frame 339 340The AE area (sx, sy, ex, ey) in the active window can be set by programming the 341registers 0x1c, 0x1d, 0x1e and 0x1f of the SN9C1xx controllers, where one unit 342corresponds to 32 pixels. 343 344[1] The frame headers exported by the SN9C105 and SN9C120 are not described. 345 346 3479. Supported devices 348==================== 349None of the names of the companies as well as their products will be mentioned 350here. They have never collaborated with the author, so no advertising. 351 352From the point of view of a driver, what unambiguously identify a device are 353its vendor and product USB identifiers. Below is a list of known identifiers of 354devices assembling the SN9C1xx PC camera controllers: 355 356Vendor ID Product ID 357--------- ---------- 3580x0458 0x7025 3590x045e 0x00f5 3600x045e 0x00f7 3610x0471 0x0327 3620x0471 0x0328 3630x0c45 0x6001 3640x0c45 0x6005 3650x0c45 0x6007 3660x0c45 0x6009 3670x0c45 0x600d 3680x0c45 0x6011 3690x0c45 0x6019 3700x0c45 0x6024 3710x0c45 0x6025 3720x0c45 0x6028 3730x0c45 0x6029 3740x0c45 0x602a 3750x0c45 0x602b 3760x0c45 0x602c 3770x0c45 0x602d 3780x0c45 0x602e 3790x0c45 0x6030 3800x0c45 0x603f 3810x0c45 0x6080 3820x0c45 0x6082 3830x0c45 0x6083 3840x0c45 0x6088 3850x0c45 0x608a 3860x0c45 0x608b 3870x0c45 0x608c 3880x0c45 0x608e 3890x0c45 0x608f 3900x0c45 0x60a0 3910x0c45 0x60a2 3920x0c45 0x60a3 3930x0c45 0x60a8 3940x0c45 0x60aa 3950x0c45 0x60ab 3960x0c45 0x60ac 3970x0c45 0x60ae 3980x0c45 0x60af 3990x0c45 0x60b0 4000x0c45 0x60b2 4010x0c45 0x60b3 4020x0c45 0x60b8 4030x0c45 0x60ba 4040x0c45 0x60bb 4050x0c45 0x60bc 4060x0c45 0x60be 4070x0c45 0x60c0 4080x0c45 0x60c2 4090x0c45 0x60c8 4100x0c45 0x60cc 4110x0c45 0x60ea 4120x0c45 0x60ec 4130x0c45 0x60ef 4140x0c45 0x60fa 4150x0c45 0x60fb 4160x0c45 0x60fc 4170x0c45 0x60fe 4180x0c45 0x6102 4190x0c45 0x6108 4200x0c45 0x610f 4210x0c45 0x6130 4220x0c45 0x6138 4230x0c45 0x613a 4240x0c45 0x613b 4250x0c45 0x613c 4260x0c45 0x613e 427 428The list above does not imply that all those devices work with this driver: up 429until now only the ones that assemble the following pairs of SN9C1xx bridges 430and image sensors are supported; kernel messages will always tell you whether 431this is the case (see "Module loading" paragraph): 432 433Image sensor / SN9C1xx bridge | SN9C10[12] SN9C103 SN9C105 SN9C120 434------------------------------------------------------------------------------- 435HV7131D Hynix Semiconductor | Yes No No No 436HV7131R Hynix Semiconductor | No Yes Yes Yes 437MI-0343 Micron Technology | Yes No No No 438MI-0360 Micron Technology | No Yes Yes Yes 439OV7630 OmniVision Technologies | Yes Yes No No 440OV7660 OmniVision Technologies | No No Yes Yes 441PAS106B PixArt Imaging | Yes No No No 442PAS202B PixArt Imaging | Yes Yes No No 443TAS5110C1B Taiwan Advanced Sensor | Yes No No No 444TAS5110D Taiwan Advanced Sensor | Yes No No No 445TAS5130D1B Taiwan Advanced Sensor | Yes No No No 446 447"Yes" means that the pair is supported by the driver, while "No" means that the 448pair does not exist or is not supported by the driver. 449 450Only some of the available control settings of each image sensor are supported 451through the V4L2 interface. 452 453Donations of new models for further testing and support would be much 454appreciated. Non-available hardware will not be supported by the author of this 455driver. 456 457 45810. Notes for V4L2 application developers 459========================================= 460This driver follows the V4L2 API specifications. In particular, it enforces two 461rules: 462 463- exactly one I/O method, either "mmap" or "read", is associated with each 464file descriptor. Once it is selected, the application must close and reopen the 465device to switch to the other I/O method; 466 467- although it is not mandatory, previously mapped buffer memory should always 468be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's. 469The same number of buffers as before will be allocated again to match the size 470of the new video frames, so you have to map the buffers again before any I/O 471attempts on them. 472 473Consistently with the hardware limits, this driver also supports image 474downscaling with arbitrary scaling factors from 1, 2 and 4 in both directions. 475However, the V4L2 API specifications don't correctly define how the scaling 476factor can be chosen arbitrarily by the "negotiation" of the "source" and 477"target" rectangles. To work around this flaw, we have added the convention 478that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the 479scaling factor is restored to 1. 480 481This driver supports two different video formats: the first one is the "8-bit 482Sequential Bayer" format and can be used to obtain uncompressed video data 483from the device through the current I/O method, while the second one provides 484either "raw" compressed video data (without frame headers not related to the 485compressed data) or standard JPEG (with frame headers). The compression quality 486may vary from 0 to 1 and can be selected or queried thanks to the 487VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP V4L2 ioctl's. For maximum flexibility, 488both the default active video format and the default compression quality 489depend on how the image sensor being used is initialized. 490 491 49211. Video frame formats [1] 493======================= 494The SN9C1xx PC Camera Controllers can send images in two possible video 495formats over the USB: either native "Sequential RGB Bayer" or compressed. 496The compression is used to achieve high frame rates. With regard to the 497SN9C101, SN9C102 and SN9C103, the compression is based on the Huffman encoding 498algorithm described below, while with regard to the SN9C105 and SN9C120 the 499compression is based on the JPEG standard. 500The current video format may be selected or queried from the user application 501by calling the VIDIOC_S_FMT or VIDIOC_G_FMT ioctl's, as described in the V4L2 502API specifications. 503 504The name "Sequential Bayer" indicates the organization of the red, green and 505blue pixels in one video frame. Each pixel is associated with a 8-bit long 506value and is disposed in memory according to the pattern shown below: 507 508B[0] G[1] B[2] G[3] ... B[m-2] G[m-1] 509G[m] R[m+1] G[m+2] R[m+2] ... G[2m-2] R[2m-1] 510... 511... B[(n-1)(m-2)] G[(n-1)(m-1)] 512... G[n(m-2)] R[n(m-1)] 513 514The above matrix also represents the sequential or progressive read-out mode of 515the (n, m) Bayer color filter array used in many CCD or CMOS image sensors. 516 517The Huffman compressed video frame consists of a bitstream that encodes for 518every R, G, or B pixel the difference between the value of the pixel itself and 519some reference pixel value. Pixels are organised in the Bayer pattern and the 520Bayer sub-pixels are tracked individually and alternatingly. For example, in 521the first line values for the B and G1 pixels are alternatingly encoded, while 522in the second line values for the G2 and R pixels are alternatingly encoded. 523 524The pixel reference value is calculated as follows: 525- the 4 top left pixels are encoded in raw uncompressed 8-bit format; 526- the value in the top two rows is the value of the pixel left of the current 527 pixel; 528- the value in the left column is the value of the pixel above the current 529 pixel; 530- for all other pixels, the reference value is the average of the value of the 531 pixel on the left and the value of the pixel above the current pixel; 532- there is one code in the bitstream that specifies the value of a pixel 533 directly (in 4-bit resolution); 534- pixel values need to be clamped inside the range [0..255] for proper 535 decoding. 536 537The algorithm purely describes the conversion from compressed Bayer code used 538in the SN9C101, SN9C102 and SN9C103 chips to uncompressed Bayer. Additional 539steps are required to convert this to a color image (i.e. a color interpolation 540algorithm). 541 542The following Huffman codes have been found: 5430: +0 (relative to reference pixel value) 544100: +4 545101: -4? 5461110xxxx: set absolute value to xxxx.0000 5471101: +11 5481111: -11 54911001: +20 550110000: -20 551110001: ??? - these codes are apparently not used 552 553[1] The Huffman compression algorithm has been reverse-engineered and 554 documented by Bertrik Sikken. 555 556 55712. Contact information 558======================= 559The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>. 560 561GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is 562'FCE635A4'; the public 1024-bit key should be available at any keyserver; 563the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. 564 565 56613. Credits 567=========== 568Many thanks to following persons for their contribute (listed in alphabetical 569order): 570 571- Luca Capello for the donation of a webcam; 572- Philippe Coval for having helped testing the PAS202BCA image sensor; 573- Joao Rodrigo Fuzaro, Joao Limirio, Claudio Filho and Caio Begotti for the 574 donation of a webcam; 575- Dennis Heitmann for the donation of a webcam; 576- Jon Hollstrom for the donation of a webcam; 577- Nick McGill for the donation of a webcam; 578- Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB 579 image sensor; 580- Stefano Mozzi, who donated 45 EU; 581- Andrew Pearce for the donation of a webcam; 582- John Pullan for the donation of a webcam; 583- Bertrik Sikken, who reverse-engineered and documented the Huffman compression 584 algorithm used in the SN9C101, SN9C102 and SN9C103 controllers and 585 implemented the first decoder; 586- Mizuno Takafumi for the donation of a webcam; 587- an "anonymous" donator (who didn't want his name to be revealed) for the 588 donation of a webcam. 589- an anonymous donator for the donation of four webcams and two boards with ten 590 image sensors. 591