| 1 | Gravis GrIP to HID adapter
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| 2 | ==========================
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| 3 |
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| 4 | GRiP is (or was?) a custom protocol designed by Gravis to allow their gamepad
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| 5 | to use more than 4 buttons on the PC joystick port. The Gravis Gamepad Pro is
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| 6 | one of the best PC gamepads ever manufactured, and the USB version is not that
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| 7 | common (and also looks less nice with the black plastic).
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| 8 |
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| 9 | This interface allows to use these gamepads on an USB port, for modern machines
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| 10 | where the traditional gameport is not available. It supports up to 4 gamepads
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| 11 | (2 gameports, each allowing to use 2 gamepads thanks to Gravis chaining system).
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| 12 |
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| 13 | The gamepads are each reported as a separate USB report, and show up as 4 independant
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| 14 | gamepads on both Windows and Haiku. Buttons are assigned in this order:
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| 15 | green, yellow, red, blue, L1, R1, start, select, R2, L2. This order is reasonable
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| 16 | (but not perfect) while allowing to reuse the bits received from the gamepad almost
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| 17 | directly to fill the HID report. The only change needed is inverting the Y axis,
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| 18 | because USB wants the up direction to be lowest values.
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| 19 |
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| 20 | It is powered by an AT90USB AVR microcontroller, because these implement USB in
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| 21 | hardware and make it easy to implement an HID device.
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| 22 |
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| 23 | You need the LUFA USB stack to compile this project. I am not including it to
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| 24 | avoid code duplication. Download and extract it yourself, or set the LUFA_PATH variable
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| 25 | to where you already have it when compiling.
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| 26 |
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| 27 | [Further reading on GrIP](http://pulkomandy.tk/_/_Electronique/_Gravis%20Interface%20Protocol)
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| 28 |
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| 29 | I have built some boards and can ship them to you if you don't want to build one yourself. The
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| 30 | cost for an assembled and tested board is 15€ (covering the cost of components and shipping).
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| 31 | Contact me if you are interested in getting one.
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