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