Documentation/i2c/busses/i2c-parport

   1 Kernel driver i2c-parport
   2
   3 Author: Jean Delvare <khali@linux-fr.org>
   4
   5 This is a unified driver for several i2c-over-parallel-port adapters,
   6 such as the ones made by Philips, Velleman or ELV. This driver is
   7 meant as a replacement for the older, individual drivers:
   8  * i2c-philips-par
   9  * i2c-elv
  10  * i2c-velleman
  11  * video/i2c-parport (NOT the same as this one, dedicated to home brew
  12                       teletext adapters)
  13
  14 It currently supports the following devices:
  15  * Philips adapter
  16  * home brew teletext adapter
  17  * Velleman K8000 adapter
  18  * ELV adapter
  19  * Analog Devices evaluation boards (ADM1025, ADM1030, ADM1031, ADM1032)
  20
  21 These devices use different pinout configurations, so you have to tell
  22 the driver what you have, using the type module parameter. There is no
  23 way to autodetect the devices. Support for different pinout configurations
  24 can be easily added when needed.
  25
  26
  27 Building your own adapter
  28 -------------------------
  29
  30 If you want to build you own i2c-over-parallel-port adapter, here is
  31 a sample electronics schema (credits go to Sylvain Munaut):
  32
  33 Device                                                      PC
  34 Side          ___________________Vdd (+)                    Side
  35                |    |         |
  36               ---  ---       ---
  37               | |  | |       | |
  38               |R|  |R|       |R|
  39               | |  | |       | |
  40               ---  ---       ---
  41                |    |         |
  42                |    |    /|   |
  43 SCL  ----------x--------o |-----------x-------------------  pin 2
  44                     |    \|   |       |
  45                     |         |       |
  46                     |   |\    |       |
  47 SDA  ----------x----x---| o---x---------------------------  pin 13
  48                |        |/            |
  49                |                      |
  50                |         /|           |
  51                ---------o |----------------x--------------  pin 3
  52                          \|           |    |
  53                                       |    |
  54                                      ---  ---
  55                                      | |  | |
  56                                      |R|  |R|
  57                                      | |  | |
  58                                      ---  ---
  59                                       |    |
  60                                      ###  ###
  61                                      GND  GND
  62
  63 Remarks:
  64  - This is the exact pinout and electronics used on the Analog Devices
  65    evaluation boards.
  66                    /|
  67  - All inverters -o |- must be 74HC05, they must be open collector output.
  68                    \|
  69  - All resitors are 10k.
  70  - Pins 18-25 of the parallel port connected to GND.
  71  - Pins 4-9 (D2-D7) could be used as VDD is the driver drives them high.
  72    The ADM1032 evaluation board uses D4-D7. Beware that the amount of
  73    current you can draw from the parallel port is limited. Also note that
  74    all connected lines MUST BE driven at the same state, else you'll short
  75    circuit the output buffers! So plugging the I2C adapter after loading
  76    the i2c-parport module might be a good safety since data line state
  77    prior to init may be unknown.
  78  - This is 5V!
  79  - Obviously you cannot read SCL (so it's not really standard-compliant).
  80    Pretty easy to add, just copy the SDA part and use another input pin.
  81    That would give (ELV compatible pinout):
  82
  83
  84 Device                                                      PC
  85 Side          ______________________________Vdd (+)         Side
  86                |    |            |    |
  87               ---  ---          ---  ---
  88               | |  | |          | |  | |
  89               |R|  |R|          |R|  |R|
  90               | |  | |          | |  | |
  91               ---  ---          ---  ---
  92                |    |            |    |
  93                |    |      |\    |    |
  94 SCL  ----------x--------x--| o---x------------------------  pin 15
  95                     |   |  |/         |
  96                     |   |             |
  97                     |   |   /|        |
  98                     |   ---o |-------------x--------------  pin 2
  99                     |       \|        |    |
 100                     |                 |    |
 101                     |                 |    |
 102                     |      |\         |    |
 103 SDA  ---------------x---x--| o--------x-------------------  pin 10
 104                         |  |/              |
 105                         |                  |
 106                         |   /|             |
 107                         ---o |------------------x---------  pin 3
 108                             \|             |    |
 109                                            |    |
 110                                           ---  ---
 111                                           | |  | |
 112                                           |R|  |R|
 113                                           | |  | |
 114                                           ---  ---
 115                                            |    |
 116                                           ###  ###
 117                                           GND  GND
 118
 119
 120 If possible, you should use the same pinout configuration as existing
 121 adapters do, so you won't even have to change the code.
 122
 123
 124 Similar (but different) drivers
 125 -------------------------------
 126
 127 This driver is NOT the same as the i2c-pport driver found in the i2c
 128 package. The i2c-pport driver makes use of modern parallel port features so
 129 that you don't need additional electronics. It has other restrictions
 130 however, and was not ported to Linux 2.6 (yet).
 131
 132 This driver is also NOT the same as the i2c-pcf-epp driver found in the
 133 lm_sensors package. The i2c-pcf-epp driver doesn't use the parallel port as
 134 an I2C bus directly. Instead, it uses it to control an external I2C bus
 135 master. That driver was not ported to Linux 2.6 (yet) either.
 136
 137
 138 Legacy documentation for Velleman adapter
 139 -----------------------------------------
 140
 141 Useful links:
 142 Velleman                http://www.velleman.be/
 143 Velleman K8000 Howto    http://howto.htlw16.ac.at/k8000-howto.html
 144
 145 The project has lead to new libs for the Velleman K8000 and K8005:
 146   LIBK8000 v1.99.1 and LIBK8005 v0.21
 147 With these libs, you can control the K8000 interface card and the K8005
 148 stepper motor card with the simple commands which are in the original
 149 Velleman software, like SetIOchannel, ReadADchannel, SendStepCCWFull and
 150 many more, using /dev/velleman.
 151   http://home.wanadoo.nl/hihihi/libk8000.htm
 152   http://home.wanadoo.nl/hihihi/libk8005.htm
 153   http://struyve.mine.nu:8080/index.php?block=k8000
 154   http://sourceforge.net/projects/libk8005/