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