gba-link-connection

A Game Boy Advance (GBA) Link Cable library to add multiplayer support to homebrew games. It provides easy-to-use C++ classes to interact with the Serial Port:

• 🎮 LinkCable.h: The classic 16-bit Multi-Player mode (up to 4 players)!
• 💻 LinkCableMultiboot.h: ‍Send Multiboot software (small 256KiB ROMs) to other GBAs with no cartridge!
• 🔌 LinkGPIO.h: Use the Link Port however you want to control any device (like LEDs, rumble motors, and that kind of stuff)!
• 🔗 LinkSPI.h: Connect with a PC (like a Raspberry Pi) using this mode. Transfer up to 2Mbit/s!
• 📻 LinkWireless.h: Connect up to 5 consoles with the Wireless Adapter!
• 📡 LinkWirelessMultiboot.h: Send Multiboot software to other GBAs over the air!

LinkCable

The library uses message queues to send/receive data and transmits when it's possible. As it uses CPU interrupts, the connection is alive even if a console drops a frame or gets stucked in a long iteration loop. After such event, all nodes end up receiving all the pending messages, so a lockstep communication protocol can be used.

Usage

• Include LinkCable.h in your game code, and read its comment for instructions.
• Check out the examples folder
  • Builds are available in Releases.
  • They can be tested on real GBAs or using emulators (NO$GBA, mGBA, or VBA-M).

Constructor options

new LinkCable(...) accepts these optional parameters:

Name	Type	Default	Description
baudRate	BaudRate	BaudRate::BAUD_RATE_1	Sets a specific baud rate.
timeout	u32	3	Number of frames without an II_SERIAL IRQ to reset the connection.
remoteTimeout	u32	5	Number of messages with 0xFFFF to mark a player as disconnected.
bufferSize	u32	30	Number of messages that the queues will be able to store.
interval	u16	50	Number of 1024cycles (61.04μs) ticks between messages (50 = 3,052ms). It's the interval of Timer #sendTimerId.
sendTimerId	u8 (0~3)	3	GBA Timer to use for sending.

Methods

Name	Return type	Description
isActive()	bool	Returns whether the library is active or not.
activate()	-	Activates the library.
deactivate()	-	Deactivates the library.
isConnected()	bool	Returns true if there are at least 2 connected players.
playerCount()	u8 (0~4)	Returns the number of connected players.
currentPlayerId()	u8 (0~3)	Returns the current player id.
canRead(playerId)	bool	Returns true if there are pending messages from player #playerId.
read(playerId)	u16	Returns one message from player #playerId.
consume()	-	Marks the current data as processed, enabling the library to fetch more.
send(data)	-	Sends data to all connected players.

Makefile actions

• make clean
• make build
• make start
• make rebuild
• make restart