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README for the GCpad core
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README for the GCpad core
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=========================
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=========================
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Version: $Date: 2004-10-28 20:00:12 $
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Version: $Id: README 41 2009-04-01 19:58:04Z arniml $
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Description
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Description
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-----------
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-----------
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The GCpad core interfaces to the gamepad used with the Nintendo Gamecube video
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The GCpad core interfaces to the gamepad used with the Nintendo Gamecube video
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gaming system. The core communicates with the gamepad using its proprietary
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gaming system. The core communicates with the gamepad using its proprietary
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communication protocol and offers the retrieved information for further
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communication protocol and offers the retrieved information for further
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processing.
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processing.
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To suit the needs of the integrating system, two different flavors of the core
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To suit the needs of the integrating system, two different flavors of the core
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are available:
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are available:
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* For simple applications the basic flavor manages all communication issues
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* For simple applications the basic flavor manages all communication issues
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with the gamepad and provides the current status of the buttons and analog
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with the gamepad and provides the current status of the buttons and analog
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axes at its interface. The integrating system does not need to interfere
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axes at its interface. The integrating system does not need to interfere
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with gamepad communication and can statically read the button and axes
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with gamepad communication and can statically read the button and axes
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status information.
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status information.
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* The full flavor allows full control of the gamepad communication by the
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* The full flavor allows full control of the gamepad communication by the
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integrating system. This flavor offers a command and response interface
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integrating system. This flavor offers a command and response interface
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which is driven by the system to send arbitrary commands to the
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which is driven by the system to send arbitrary commands to the
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gamepad. The response of the gamepad is available for further processing.
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gamepad. The response of the gamepad is available for further processing.
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Connecting the Pad
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Connecting the Pad
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------------------
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------------------
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Information is exchanged between the gamepad and the host side over a single
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Information is exchanged between the gamepad and the host side over a single
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wire. Both sides seem to implement an open-collector style output
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wire. Both sides seem to implement an open-collector style output
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driver. Therefore, an external pull-up resistor of 1kOhm to the 3.43V supply
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driver. Therefore, an external pull-up resistor of 1kOhm to the 3.43V supply
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is required at the DATA line.
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is required at the DATA line.
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Sticking exactly to the 3.3V supply seems not to be necessary. I use the 3.3V
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Sticking exactly to the 3.3V supply seems not to be necessary. I use the 3.3V
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supply which is available from the FPGA board. Please note that the 5V supply
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supply which is available from the FPGA board. Please note that the 5V supply
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is required for certain controller types even if the rumble motor is not used.
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is required for certain controller types even if the rumble motor is not used.
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The connector seems to be a special type designed for the Gamecube. It might
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The connector seems to be a special type designed for the Gamecube. It might
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be hard to find a matching counterpart. If you do not want to rip up the
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be hard to find a matching counterpart. If you do not want to rip up the
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controller cable then your alternative option might be to reuse an extension
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controller cable then your alternative option might be to reuse an extension
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cable. They are quite cheap and pass through all required wires. Just remove
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cable. They are quite cheap and pass through all required wires. Just remove
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the connector that is plugged into the console and attach your favorite
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the connector that is plugged into the console and attach your favorite
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standard connector.
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standard connector.
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See gcpad.png.
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See gcpad.png.
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Verification
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Verification
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The GCpad core comes with a simple testbench that includes a simulation model
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The GCpad core comes with a simple testbench that includes a simulation model
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of a Gamecube controller. Serial information is sent to the core and the
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of a Gamecube controller. Serial information is sent to the core and the
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reported button states are compared against the input. Both flavors are tested
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reported button states are compared against the input. Both flavors are tested
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in parallel there.
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in parallel there.
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You should normally not need to run the testbench. But in case you modified
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You should normally not need to run the testbench. But in case you modified
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the VHDL code the testbench gives some hints if the design has been broken.
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the VHDL code the testbench gives some hints if the design has been broken.
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Directory Structure
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Directory Structure
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-------------------
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-------------------
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The core's directory structure follows the proposal of OpenCores.org.
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The core's directory structure follows the proposal of OpenCores.org.
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gcpad
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gcpad
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\--+-- doc : Integration Manual
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\--+-- doc : Integration Manual
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+-- rtl
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+-- rtl
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| \-- vhdl : VHDL code containing the RTL description
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| \-- vhdl : VHDL code containing the RTL description
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| of the core.
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| of the core.
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+-- bench
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+-- bench
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| \-- vhdl : VHDL testbench code.
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| \-- vhdl : VHDL testbench code.
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\-- sim
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\-- sim
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\-- rtl_sim : Directory for running simulations.
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\-- rtl_sim : Directory for running simulations.
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Compiling the VHDL Code
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Compiling the VHDL Code
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-----------------------
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-----------------------
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VHDL compilation and simulation tasks take place inside in sim/rtl_sim
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VHDL compilation and simulation tasks take place inside in sim/rtl_sim
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directory. The project setup supports only the GHDL simulator (see
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directory. The project setup supports only the GHDL simulator (see
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http://ghdl.free.fr).
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http://ghdl.free.fr).
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To compile the code simply type at the shell
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To compile the code simply type at the shell
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$ make
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$ make
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This should result in a file called tb_behav_c0 which can be executed as any
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This should result in a file called tb_behav_c0 which can be executed as any
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other executable.
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other executable.
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The basic simple sequence list can be found in COMPILE_LIST. This can be
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The basic simple sequence list can be found in COMPILE_LIST. This can be
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useful to quickly set up the analyze stage of any compiler or
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useful to quickly set up the analyze stage of any compiler or
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synthesizer. Especially when synthesizing the code, you want to skip the VHDL
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synthesizer. Especially when synthesizing the code, you want to skip the VHDL
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configurations in *-c.vhd and everything below the bench/ directory.
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configurations in *-c.vhd and everything below the bench/ directory.
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References
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References
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----------
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----------
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* James' excellent page covering many details of the Gamecube controller
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* James' excellent page covering many details of the Gamecube controller
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protocol
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protocol
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http://www.int03.co.uk/crema/hardware/gamecube/gc-control.htm
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http://www.int03.co.uk/crema/hardware/gamecube/gc-control.htm
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* Yet Another Gamecube Documentation
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* Yet Another Gamecube Documentation
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http://www.gc-linux.org/docs/yagcd/index.html
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http://www.gc-linux.org/docs/yagcd/index.html
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Refer to section 5.8, 9.1 and 9.2.
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Refer to section 5.8, 9.1 and 9.2.
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