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===================================================================
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A driver for a selfmade cheap BT8xx based PCI GPIO-card (bt8xxgpio)
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===================================================================
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For advanced documentation, see http://www.bu3sch.de/btgpio.php
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A generic digital 24-port PCI GPIO card can be built out of an ordinary
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Brooktree bt848, bt849, bt878 or bt879 based analog TV tuner card. The
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Brooktree chip is used in old analog Hauppauge WinTV PCI cards. You can easily
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find them used for low prices on the net.
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The bt8xx chip does have 24 digital GPIO ports.
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These ports are accessible via 24 pins on the SMD chip package.
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How to physically access the GPIO pins
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======================================
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The are several ways to access these pins. One might unsolder the whole chip
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and put it on a custom PCI board, or one might only unsolder each individual
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GPIO pin and solder that to some tiny wire. As the chip package really is tiny
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there are some advanced soldering skills needed in any case.
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The physical pinouts are drawn in the following ASCII art.
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The GPIO pins are marked with G00-G23::
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G G G G G G G G G G G G G G G G G G
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0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7
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---------------------------------------------------------------------------
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--| ^ ^ |--
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--| pin 86 pin 67 |--
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--| |--
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--| pin 61 > |-- G18
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--| |-- G19
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--| |-- G20
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--| |-- G21
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--| |-- G22
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--| pin 56 > |-- G23
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--| |--
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--| Brooktree 878/879 |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| |--
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--| O |--
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--| |--
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---------------------------------------------------------------------------
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^
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This is pin 1
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