Based on kernel version 3.13. Page generated on 2014-01-20 22:05 EST.
1 2 SN9C1xx PC Camera Controllers 3 Driver for Linux 4 ============================= 5 6 - Documentation - 7 8 9 Index 10 ===== 11 1. Copyright 12 2. Disclaimer 13 3. License 14 4. Overview and features 15 5. Module dependencies 16 6. Module loading 17 7. Module parameters 18 8. Optional device control through "sysfs" 19 9. Supported devices 20 10. Notes for V4L2 application developers 21 11. Video frame formats 22 12. Contact information 23 13. Credits 24 25 26 1. Copyright 27 ============ 28 Copyright (C) 2004-2007 by Luca Risolia <luca.risolia@studio.unibo.it> 29 30 31 2. Disclaimer 32 ============= 33 SONiX is a trademark of SONiX Technology Company Limited, inc. 34 This software is not sponsored or developed by SONiX. 35 36 37 3. License 38 ========== 39 This program is free software; you can redistribute it and/or modify 40 it under the terms of the GNU General Public License as published by 41 the Free Software Foundation; either version 2 of the License, or 42 (at your option) any later version. 43 44 This program is distributed in the hope that it will be useful, 45 but WITHOUT ANY WARRANTY; without even the implied warranty of 46 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 47 GNU General Public License for more details. 48 49 You should have received a copy of the GNU General Public License 50 along with this program; if not, write to the Free Software 51 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 52 53 54 4. Overview and features 55 ======================== 56 This driver attempts to support the video interface of the devices assembling 57 the SONiX SN9C101, SN9C102, SN9C103, SN9C105 and SN9C120 PC Camera Controllers 58 ("SN9C1xx" from now on). 59 60 The driver relies on the Video4Linux2 and USB core modules. It has been 61 designed to run properly on SMP systems as well. 62 63 The latest version of the SN9C1xx driver can be found at the following URL: 64 http://www.linux-projects.org/ 65 66 Some 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 96 5. Module dependencies 97 ====================== 98 For it to work properly, the driver needs kernel support for Video4Linux and 99 USB. 100 101 The following options of the kernel configuration file must be enabled and 102 corresponding modules must be compiled: 103 104 # Multimedia devices 105 # 106 CONFIG_VIDEO_DEV=m 107 108 To 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 117 118 In addition, depending on the hardware being used, the modules below are 119 necessary: 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 126 127 The SN9C103, SN9c105 and SN9C120 controllers also provide a built-in microphone 128 interface. 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 141 142 And finally: 143 144 # USB Multimedia devices 145 # 146 CONFIG_USB_SN9C102=m 147 148 149 6. Module loading 150 ================= 151 To use the driver, it is necessary to load the "sn9c102" module into memory 152 after 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". 155 156 Loading can be done as shown below: 157 158 [root@localhost home]# modprobe sn9c102 159 160 Note that the module is called "sn9c102" for historic reasons, although it 161 does not just support the SN9C102. 162 163 At this point all the devices supported by the driver and connected to the USB 164 ports should be recognized. You can invoke "dmesg" to analyze kernel messages 165 and verify that the loading process has gone well: 166 167 [user@localhost home]$ dmesg 168 169 or, to isolate all the kernel messages generated by the driver: 170 171 [user@localhost home]$ dmesg | grep sn9c102 172 173 174 7. Module parameters 175 ==================== 176 Module parameters are listed below: 177 ------------------------------------------------------------------------------- 178 Name: video_nr 179 Type: short array (min = 0, max = 64) 180 Syntax: <-1|n[,...]> 181 Description: 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. 189 Default: -1 190 ------------------------------------------------------------------------------- 191 Name: force_munmap 192 Type: bool array (min = 0, max = 64) 193 Syntax: <0|1[,...]> 194 Description: 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) 200 Default: 0 201 ------------------------------------------------------------------------------- 202 Name: frame_timeout 203 Type: uint array (min = 0, max = 64) 204 Syntax: <0|n[,...]> 205 Description: 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. 209 Default: 2 210 ------------------------------------------------------------------------------- 211 Name: debug 212 Type: ushort 213 Syntax: <n> 214 Description: Debugging information level, from 0 to 3: 215 0 = none (use carefully) 216 1 = critical errors 217 2 = significant information 218 3 = more verbose messages 219 Level 3 is useful for testing only. It also shows some more 220 information about the hardware being detected. 221 This parameter can be changed at runtime thanks to the /sys 222 filesystem interface. 223 Default: 2 224 ------------------------------------------------------------------------------- 225 226 227 8. Optional device control through "sysfs" [1] 228 ========================================== 229 If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled, 230 it is possible to read and write both the SN9C1xx and the image sensor 231 registers by using the "sysfs" filesystem interface. 232 233 Every time a supported device is recognized, a write-only file named "green" is 234 created in the /sys/class/video4linux/videoX directory. You can set the green 235 channel's gain by writing the desired value to it. The value may range from 0 236 to 15 for the SN9C101 or SN9C102 bridges, from 0 to 127 for the SN9C103, 237 SN9C105 and SN9C120 bridges. 238 Similarly, only for the SN9C103, SN9C105 and SN9C120 controllers, blue and red 239 gain control files are available in the same directory, for which accepted 240 values may range from 0 to 127. 241 242 There 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 244 SN9C1xx 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 246 reading/writing operations are addressed at through "val" and "i2c_val". Their 247 use is not intended for end-users. Note that "i2c_reg" and "i2c_val" will not 248 be created if the sensor does not actually support the standard I2C protocol or 249 its registers are not 8-bit long. Also, remember that you must be logged in as 250 root before writing to them. 251 252 As an example, suppose we were to want to read the value contained in the 253 register number 1 of the sensor register table - which is usually the product 254 identifier - 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 259 260 Note that "cat" will fail if sensor registers cannot be read. 261 262 Now 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 266 267 Note that the SN9C1xx always returns 0 when some of its registers are read. 268 To avoid race conditions, all the I/O accesses to the above files are 269 serialized. 270 The sysfs interface also provides the "frame_header" entry, which exports the 271 frame header of the most recent requested and captured video frame. The header 272 is always 18-bytes long and is appended to every video frame by the SN9C1xx 273 controllers. As an example, this additional information can be used by the user 274 application for implementing auto-exposure features via software. 275 276 The following table describes the frame header exported by the SN9C101 and 277 SN9C102: 278 279 Byte # Value or bits Description 280 ------ ------------- ----------- 281 0x00 0xFF Frame synchronisation pattern 282 0x01 0xFF Frame synchronisation pattern 283 0x02 0x00 Frame synchronisation pattern 284 0x03 0xC4 Frame synchronisation pattern 285 0x04 0xC4 Frame synchronisation pattern 286 0x05 0x96 Frame synchronisation pattern 287 0x06 [3:0] Read channel gain control = (1+R_GAIN/8) 288 [7:4] Blue channel gain control = (1+B_GAIN/8) 289 0x07 [ 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 295 0x08 [7:0] Y sum inside Auto-Exposure area (low-byte) 296 0x09 [7:0] Y sum inside Auto-Exposure area (high-byte) 297 where Y sum = (R/4 + 5G/16 + B/8) / 32 298 0x0A [7:0] Y sum outside Auto-Exposure area (low-byte) 299 0x0B [7:0] Y sum outside Auto-Exposure area (high-byte) 300 where Y sum = (R/4 + 5G/16 + B/8) / 128 301 0x0C 0xXX Not used 302 0x0D 0xXX Not used 303 0x0E 0xXX Not used 304 0x0F 0xXX Not used 305 0x10 0xXX Not used 306 0x11 0xXX Not used 307 308 The following table describes the frame header exported by the SN9C103: 309 310 Byte # Value or bits Description 311 ------ ------------- ----------- 312 0x00 0xFF Frame synchronisation pattern 313 0x01 0xFF Frame synchronisation pattern 314 0x02 0x00 Frame synchronisation pattern 315 0x03 0xC4 Frame synchronisation pattern 316 0x04 0xC4 Frame synchronisation pattern 317 0x05 0x96 Frame synchronisation pattern 318 0x06 [6:0] Read channel gain control = (1/2+R_GAIN/64) 319 0x07 [6:0] Blue channel gain control = (1/2+B_GAIN/64) 320 [7:4] 321 0x08 [ 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 327 0x09 [7:0] Y sum inside Auto-Exposure area (low-byte) 328 0x0A [7:0] Y sum inside Auto-Exposure area (high-byte) 329 where Y sum = (R/4 + 5G/16 + B/8) / 32 330 0x0B [7:0] Y sum outside Auto-Exposure area (low-byte) 331 0x0C [7:0] Y sum outside Auto-Exposure area (high-byte) 332 where Y sum = (R/4 + 5G/16 + B/8) / 128 333 0x0D [1:0] Audio frame number 334 [ 2 ] 1 = Audio is recording 335 0x0E [7:0] Audio summation (low-byte) 336 0x0F [7:0] Audio summation (high-byte) 337 0x10 [7:0] Audio sample count 338 0x11 [7:0] Audio peak data in audio frame 339 340 The AE area (sx, sy, ex, ey) in the active window can be set by programming the 341 registers 0x1c, 0x1d, 0x1e and 0x1f of the SN9C1xx controllers, where one unit 342 corresponds to 32 pixels. 343 344 [1] The frame headers exported by the SN9C105 and SN9C120 are not described. 345 346 347 9. Supported devices 348 ==================== 349 None of the names of the companies as well as their products will be mentioned 350 here. They have never collaborated with the author, so no advertising. 351 352 From the point of view of a driver, what unambiguously identify a device are 353 its vendor and product USB identifiers. Below is a list of known identifiers of 354 devices assembling the SN9C1xx PC camera controllers: 355 356 Vendor ID Product ID 357 --------- ---------- 358 0x0458 0x7025 359 0x045e 0x00f5 360 0x045e 0x00f7 361 0x0471 0x0327 362 0x0471 0x0328 363 0x0c45 0x6001 364 0x0c45 0x6005 365 0x0c45 0x6007 366 0x0c45 0x6009 367 0x0c45 0x600d 368 0x0c45 0x6011 369 0x0c45 0x6019 370 0x0c45 0x6024 371 0x0c45 0x6025 372 0x0c45 0x6028 373 0x0c45 0x6029 374 0x0c45 0x602a 375 0x0c45 0x602b 376 0x0c45 0x602c 377 0x0c45 0x602d 378 0x0c45 0x602e 379 0x0c45 0x6030 380 0x0c45 0x603f 381 0x0c45 0x6080 382 0x0c45 0x6082 383 0x0c45 0x6083 384 0x0c45 0x6088 385 0x0c45 0x608a 386 0x0c45 0x608b 387 0x0c45 0x608c 388 0x0c45 0x608e 389 0x0c45 0x608f 390 0x0c45 0x60a0 391 0x0c45 0x60a2 392 0x0c45 0x60a3 393 0x0c45 0x60a8 394 0x0c45 0x60aa 395 0x0c45 0x60ab 396 0x0c45 0x60ac 397 0x0c45 0x60ae 398 0x0c45 0x60af 399 0x0c45 0x60b0 400 0x0c45 0x60b2 401 0x0c45 0x60b3 402 0x0c45 0x60b8 403 0x0c45 0x60ba 404 0x0c45 0x60bb 405 0x0c45 0x60bc 406 0x0c45 0x60be 407 0x0c45 0x60c0 408 0x0c45 0x60c2 409 0x0c45 0x60c8 410 0x0c45 0x60cc 411 0x0c45 0x60ea 412 0x0c45 0x60ec 413 0x0c45 0x60ef 414 0x0c45 0x60fa 415 0x0c45 0x60fb 416 0x0c45 0x60fc 417 0x0c45 0x60fe 418 0x0c45 0x6102 419 0x0c45 0x6108 420 0x0c45 0x610f 421 0x0c45 0x6130 422 0x0c45 0x6138 423 0x0c45 0x613a 424 0x0c45 0x613b 425 0x0c45 0x613c 426 0x0c45 0x613e 427 428 The list above does not imply that all those devices work with this driver: up 429 until now only the ones that assemble the following pairs of SN9C1xx bridges 430 and image sensors are supported; kernel messages will always tell you whether 431 this is the case (see "Module loading" paragraph): 432 433 Image sensor / SN9C1xx bridge | SN9C10[12] SN9C103 SN9C105 SN9C120 434 ------------------------------------------------------------------------------- 435 HV7131D Hynix Semiconductor | Yes No No No 436 HV7131R Hynix Semiconductor | No Yes Yes Yes 437 MI-0343 Micron Technology | Yes No No No 438 MI-0360 Micron Technology | No Yes Yes Yes 439 OV7630 OmniVision Technologies | Yes Yes Yes Yes 440 OV7660 OmniVision Technologies | No No Yes Yes 441 PAS106B PixArt Imaging | Yes No No No 442 PAS202B PixArt Imaging | Yes Yes No No 443 TAS5110C1B Taiwan Advanced Sensor | Yes No No No 444 TAS5110D Taiwan Advanced Sensor | Yes No No No 445 TAS5130D1B Taiwan Advanced Sensor | Yes No No No 446 447 "Yes" means that the pair is supported by the driver, while "No" means that the 448 pair does not exist or is not supported by the driver. 449 450 Only some of the available control settings of each image sensor are supported 451 through the V4L2 interface. 452 453 Donations of new models for further testing and support would be much 454 appreciated. Non-available hardware will not be supported by the author of this 455 driver. 456 457 458 10. Notes for V4L2 application developers 459 ========================================= 460 This driver follows the V4L2 API specifications. In particular, it enforces two 461 rules: 462 463 - exactly one I/O method, either "mmap" or "read", is associated with each 464 file descriptor. Once it is selected, the application must close and reopen the 465 device to switch to the other I/O method; 466 467 - although it is not mandatory, previously mapped buffer memory should always 468 be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's. 469 The same number of buffers as before will be allocated again to match the size 470 of the new video frames, so you have to map the buffers again before any I/O 471 attempts on them. 472 473 Consistently with the hardware limits, this driver also supports image 474 downscaling with arbitrary scaling factors from 1, 2 and 4 in both directions. 475 However, the V4L2 API specifications don't correctly define how the scaling 476 factor can be chosen arbitrarily by the "negotiation" of the "source" and 477 "target" rectangles. To work around this flaw, we have added the convention 478 that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the 479 scaling factor is restored to 1. 480 481 This driver supports two different video formats: the first one is the "8-bit 482 Sequential Bayer" format and can be used to obtain uncompressed video data 483 from the device through the current I/O method, while the second one provides 484 either "raw" compressed video data (without frame headers not related to the 485 compressed data) or standard JPEG (with frame headers). The compression quality 486 may vary from 0 to 1 and can be selected or queried thanks to the 487 VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP V4L2 ioctl's. For maximum flexibility, 488 both the default active video format and the default compression quality 489 depend on how the image sensor being used is initialized. 490 491 492 11. Video frame formats [1] 493 ======================= 494 The SN9C1xx PC Camera Controllers can send images in two possible video 495 formats over the USB: either native "Sequential RGB Bayer" or compressed. 496 The compression is used to achieve high frame rates. With regard to the 497 SN9C101, SN9C102 and SN9C103, the compression is based on the Huffman encoding 498 algorithm described below, while with regard to the SN9C105 and SN9C120 the 499 compression is based on the JPEG standard. 500 The current video format may be selected or queried from the user application 501 by calling the VIDIOC_S_FMT or VIDIOC_G_FMT ioctl's, as described in the V4L2 502 API specifications. 503 504 The name "Sequential Bayer" indicates the organization of the red, green and 505 blue pixels in one video frame. Each pixel is associated with a 8-bit long 506 value and is disposed in memory according to the pattern shown below: 507 508 B[0] G[1] B[2] G[3] ... B[m-2] G[m-1] 509 G[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)] 513 514 The above matrix also represents the sequential or progressive read-out mode of 515 the (n, m) Bayer color filter array used in many CCD or CMOS image sensors. 516 517 The Huffman compressed video frame consists of a bitstream that encodes for 518 every R, G, or B pixel the difference between the value of the pixel itself and 519 some reference pixel value. Pixels are organised in the Bayer pattern and the 520 Bayer sub-pixels are tracked individually and alternatingly. For example, in 521 the first line values for the B and G1 pixels are alternatingly encoded, while 522 in the second line values for the G2 and R pixels are alternatingly encoded. 523 524 The 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. 536 537 The algorithm purely describes the conversion from compressed Bayer code used 538 in the SN9C101, SN9C102 and SN9C103 chips to uncompressed Bayer. Additional 539 steps are required to convert this to a color image (i.e. a color interpolation 540 algorithm). 541 542 The following Huffman codes have been found: 543 0: +0 (relative to reference pixel value) 544 100: +4 545 101: -4? 546 1110xxxx: set absolute value to xxxx.0000 547 1101: +11 548 1111: -11 549 11001: +20 550 110000: -20 551 110001: ??? - these codes are apparently not used 552 553 [1] The Huffman compression algorithm has been reverse-engineered and 554 documented by Bertrik Sikken. 555 556 557 12. Contact information 558 ======================= 559 The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>. 560 561 GPG/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; 563 the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. 564 565 566 13. Credits 567 =========== 568 Many thanks to following persons for their contribute (listed in alphabetical 569 order): 570 571 - David Anderson for the donation of a webcam; 572 - Luca Capello for the donation of a webcam; 573 - Philippe Coval for having helped testing the PAS202BCA image sensor; 574 - Joao Rodrigo Fuzaro, Joao Limirio, Claudio Filho and Caio Begotti for the 575 donation of a webcam; 576 - Dennis Heitmann for the donation of a webcam; 577 - Jon Hollstrom for the donation of a webcam; 578 - Nick McGill for the donation of a webcam; 579 - Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB 580 image sensor; 581 - Stefano Mozzi, who donated 45 EU; 582 - Andrew Pearce for the donation of a webcam; 583 - John Pullan for the donation of a webcam; 584 - Bertrik Sikken, who reverse-engineered and documented the Huffman compression 585 algorithm used in the SN9C101, SN9C102 and SN9C103 controllers and 586 implemented the first decoder; 587 - Ronny Standke for the donation of a webcam; 588 - Mizuno Takafumi for the donation of a webcam; 589 - an "anonymous" donator (who didn't want his name to be revealed) for the 590 donation of a webcam. 591 - an anonymous donator for the donation of four webcams and two boards with ten 592 image sensors.