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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/i2c/busses/i2c-parport
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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1Kernel driver i2c-parport
2
3Author: Jean Delvare <khali@linux-fr.org>
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 * Philips adapter
16 * home brew teletext adapter
17 * Velleman K8000 adapter
18 * ELV adapter
19 * Analog Devices evaluation boards (ADM1025, ADM1030, ADM1031, ADM1032)
20
21These devices use different pinout configurations, so you have to tell
22the driver what you have, using the type module parameter. There is no
23way to autodetect the devices. Support for different pinout configurations
24can be easily added when needed.
25
26
27Building your own adapter
28-------------------------
29
30If you want to build you own i2c-over-parallel-port adapter, here is
31a sample electronics schema (credits go to Sylvain Munaut):
32
33Device PC
34Side ___________________Vdd (+) Side
35 | | |
36 --- --- ---
37 | | | | | |
38 |R| |R| |R|
39 | | | | | |
40 --- --- ---
41 | | |
42 | | /| |
43SCL ----------x--------o |-----------x------------------- pin 2
44 | \| | |
45 | | |
46 | |\ | |
47SDA ----------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
63Remarks:
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
84Device PC
85Side ______________________________Vdd (+) Side
86 | | | |
87 --- --- --- ---
88 | | | | | | | |
89 |R| |R| |R| |R|
90 | | | | | | | |
91 --- --- --- ---
92 | | | |
93 | | |\ | |
94SCL ----------x--------x--| o---x------------------------ pin 15
95 | | |/ |
96 | | |
97 | | /| |
98 | ---o |-------------x-------------- pin 2
99 | \| | |
100 | | |
101 | | |
102 | |\ | |
103SDA ---------------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
120If possible, you should use the same pinout configuration as existing
121adapters do, so you won't even have to change the code.
122
123
124Similar (but different) drivers
125-------------------------------
126
127This driver is NOT the same as the i2c-pport driver found in the i2c
128package. The i2c-pport driver makes use of modern parallel port features so
129that you don't need additional electronics. It has other restrictions
130however, and was not ported to Linux 2.6 (yet).
131
132This driver is also NOT the same as the i2c-pcf-epp driver found in the
133lm_sensors package. The i2c-pcf-epp driver doesn't use the parallel port as
134an I2C bus directly. Instead, it uses it to control an external I2C bus
135master. That driver was not ported to Linux 2.6 (yet) either.
136
137
138Legacy documentation for Velleman adapter
139-----------------------------------------
140
141Useful links:
142Velleman http://www.velleman.be/
143Velleman K8000 Howto http://howto.htlw16.ac.at/k8000-howto.html
144
145The project has lead to new libs for the Velleman K8000 and K8005:
146 LIBK8000 v1.99.1 and LIBK8005 v0.21
147With these libs, you can control the K8000 interface card and the K8005
148stepper motor card with the simple commands which are in the original
149Velleman software, like SetIOchannel, ReadADchannel, SendStepCCWFull and
150many 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/