1=========================
2Kernel driver i2c-parport
3=========================
4
5Author: Jean Delvare <jdelvare@suse.de>
6
7This is a unified driver for several i2c-over-parallel-port adapters,
8such as the ones made by Philips, Velleman or ELV. This driver is
9meant as a replacement for the older, individual drivers:
10
11 * i2c-philips-par
12 * i2c-elv
13 * i2c-velleman
14 * video/i2c-parport
15   (NOT the same as this one, dedicated to home brew teletext adapters)
16
17It currently supports the following devices:
18
19 * (type=0) Philips adapter
20 * (type=1) home brew teletext adapter
21 * (type=2) Velleman K8000 adapter
22 * (type=3) ELV adapter
23 * (type=4) Analog Devices ADM1032 evaluation board
24 * (type=5) Analog Devices evaluation boards: ADM1025, ADM1030, ADM1031
25 * (type=6) Barco LPT->DVI (K5800236) adapter
26 * (type=7) One For All JP1 parallel port adapter
27 * (type=8) VCT-jig
28
29These devices use different pinout configurations, so you have to tell
30the driver what you have, using the type module parameter. There is no
31way to autodetect the devices. Support for different pinout configurations
32can be easily added when needed.
33
34Earlier kernels defaulted to type=0 (Philips).  But now, if the type
35parameter is missing, the driver will simply fail to initialize.
36
37SMBus alert support is available on adapters which have this line properly
38connected to the parallel port's interrupt pin.
39
40
41Building your own adapter
42-------------------------
43
44If you want to build you own i2c-over-parallel-port adapter, here is
45a sample electronics schema (credits go to Sylvain Munaut)::
46
47  Device                                                      PC
48  Side          ___________________Vdd (+)                    Side
49                 |    |         |
50                ---  ---       ---
51                | |  | |       | |
52                |R|  |R|       |R|
53                | |  | |       | |
54                ---  ---       ---
55                 |    |         |
56                 |    |    /|   |
57  SCL  ----------x--------o |-----------x-------------------  pin 2
58                      |    \|   |       |
59                      |         |       |
60                      |   |\    |       |
61  SDA  ----------x----x---| o---x---------------------------  pin 13
62                 |        |/            |
63                 |                      |
64                 |         /|           |
65                 ---------o |----------------x--------------  pin 3
66                           \|           |    |
67                                        |    |
68                                       ---  ---
69                                       | |  | |
70                                       |R|  |R|
71                                       | |  | |
72                                       ---  ---
73                                        |    |
74                                       ###  ###
75                                       GND  GND
76
77Remarks:
78 - This is the exact pinout and electronics used on the Analog Devices
79   evaluation boards.
80 - All inverters::
81
82                   /|
83                 -o |-
84                   \|
85
86   must be 74HC05, they must be open collector output.
87 - All resitors are 10k.
88 - Pins 18-25 of the parallel port connected to GND.
89 - Pins 4-9 (D2-D7) could be used as VDD is the driver drives them high.
90   The ADM1032 evaluation board uses D4-D7. Beware that the amount of
91   current you can draw from the parallel port is limited. Also note that
92   all connected lines MUST BE driven at the same state, else you'll short
93   circuit the output buffers! So plugging the I2C adapter after loading
94   the i2c-parport module might be a good safety since data line state
95   prior to init may be unknown.
96 - This is 5V!
97 - Obviously you cannot read SCL (so it's not really standard-compliant).
98   Pretty easy to add, just copy the SDA part and use another input pin.
99   That would give (ELV compatible pinout)::
100
101
102      Device                                                      PC
103      Side          ______________________________Vdd (+)         Side
104                     |    |            |    |
105                    ---  ---          ---  ---
106                    | |  | |          | |  | |
107                    |R|  |R|          |R|  |R|
108                    | |  | |          | |  | |
109                    ---  ---          ---  ---
110                     |    |            |    |
111                     |    |      |\    |    |
112      SCL  ----------x--------x--| o---x------------------------  pin 15
113                          |   |  |/         |
114                          |   |             |
115                          |   |   /|        |
116                          |   ---o |-------------x--------------  pin 2
117                          |       \|        |    |
118                          |                 |    |
119                          |                 |    |
120                          |      |\         |    |
121      SDA  ---------------x---x--| o--------x-------------------  pin 10
122                              |  |/              |
123                              |                  |
124                              |   /|             |
125                              ---o |------------------x---------  pin 3
126                                  \|             |    |
127                                                 |    |
128                                                ---  ---
129                                                | |  | |
130                                                |R|  |R|
131                                                | |  | |
132                                                ---  ---
133                                                 |    |
134                                                ###  ###
135                                                GND  GND
136
137
138If possible, you should use the same pinout configuration as existing
139adapters do, so you won't even have to change the code.
140
141
142Similar (but different) drivers
143-------------------------------
144
145This driver is NOT the same as the i2c-pport driver found in the i2c
146package. The i2c-pport driver makes use of modern parallel port features so
147that you don't need additional electronics. It has other restrictions
148however, and was not ported to Linux 2.6 (yet).
149
150This driver is also NOT the same as the i2c-pcf-epp driver found in the
151lm_sensors package. The i2c-pcf-epp driver doesn't use the parallel port as
152an I2C bus directly. Instead, it uses it to control an external I2C bus
153master. That driver was not ported to Linux 2.6 (yet) either.
154
155
156Legacy documentation for Velleman adapter
157-----------------------------------------
158
159Useful links:
160
161- Velleman                http://www.velleman.be/
162- Velleman K8000 Howto    http://howto.htlw16.ac.at/k8000-howto.html
163
164The project has lead to new libs for the Velleman K8000 and K8005:
165
166  LIBK8000 v1.99.1 and LIBK8005 v0.21
167
168With these libs, you can control the K8000 interface card and the K8005
169stepper motor card with the simple commands which are in the original
170Velleman software, like SetIOchannel, ReadADchannel, SendStepCCWFull and
171many more, using /dev/velleman.
172
173  - http://home.wanadoo.nl/hihihi/libk8000.htm
174  - http://home.wanadoo.nl/hihihi/libk8005.htm
175  - http://struyve.mine.nu:8080/index.php?block=k8000
176  - http://sourceforge.net/projects/libk8005/
177
178
179One For All JP1 parallel port adapter
180-------------------------------------
181
182The JP1 project revolves around a set of remote controls which expose
183the I2C bus their internal configuration EEPROM lives on via a 6 pin
184jumper in the battery compartment. More details can be found at:
185
186http://www.hifi-remote.com/jp1/
187
188Details of the simple parallel port hardware can be found at:
189
190http://www.hifi-remote.com/jp1/hardware.shtml
191