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Documentation / bt8xxgpio.txt


Based on kernel version 4.16.1. Page generated on 2018-04-09 11:52 EST.

1	===================================================================
2	A driver for a selfmade cheap BT8xx based PCI GPIO-card (bt8xxgpio)
3	===================================================================
4	
5	For advanced documentation, see http://www.bu3sch.de/btgpio.php
6	
7	A generic digital 24-port PCI GPIO card can be built out of an ordinary
8	Brooktree bt848, bt849, bt878 or bt879 based analog TV tuner card. The
9	Brooktree chip is used in old analog Hauppauge WinTV PCI cards. You can easily
10	find them used for low prices on the net.
11	
12	The bt8xx chip does have 24 digital GPIO ports.
13	These ports are accessible via 24 pins on the SMD chip package.
14	
15	
16	How to physically access the GPIO pins
17	======================================
18	
19	The are several ways to access these pins. One might unsolder the whole chip
20	and put it on a custom PCI board, or one might only unsolder each individual
21	GPIO pin and solder that to some tiny wire. As the chip package really is tiny
22	there are some advanced soldering skills needed in any case.
23	
24	The physical pinouts are drawn in the following ASCII art.
25	The GPIO pins are marked with G00-G23::
26	
27	                                           G G G G G G G G G G G G     G G G G G G
28	                                           0 0 0 0 0 0 0 0 0 0 1 1     1 1 1 1 1 1
29	                                           0 1 2 3 4 5 6 7 8 9 0 1     2 3 4 5 6 7
30	           | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
31	           ---------------------------------------------------------------------------
32	         --|                               ^                                     ^   |--
33	         --|                               pin 86                           pin 67   |--
34	         --|                                                                         |--
35	         --|                                                               pin 61 >  |-- G18
36	         --|                                                                         |-- G19
37	         --|                                                                         |-- G20
38	         --|                                                                         |-- G21
39	         --|                                                                         |-- G22
40	         --|                                                               pin 56 >  |-- G23
41	         --|                                                                         |--
42	         --|                           Brooktree 878/879                             |--
43	         --|                                                                         |--
44	         --|                                                                         |--
45	         --|                                                                         |--
46	         --|                                                                         |--
47	         --|                                                                         |--
48	         --|                                                                         |--
49	         --|                                                                         |--
50	         --|                                                                         |--
51	         --|                                                                         |--
52	         --|                                                                         |--
53	         --|                                                                         |--
54	         --|                                                                         |--
55	         --|                                                                         |--
56	         --|   O                                                                     |--
57	         --|                                                                         |--
58	           ---------------------------------------------------------------------------
59	           | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
60	           ^
61	           This is pin 1
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