Hello world — Butano
The two-square demo using Butano sprites and C++. It follows the same session, matchmaking and polling flow as the plain C example.
Build and run
Install Butano/Python and set the shared key. From the SDK root:
make -C examples/hello_world_butano LIBBUTANO=/path/to/butano/butano -j2
The path must contain butano.mak; DEVKITARM must be set.
Output: examples/hello_world_butano/hello_world_butano.gba.
Load the same ROM on two consoles with configured CanoFlash devices. Connection starts automatically. Both use a public two-seat room with empty parameters. Do not mix this ROM with the plain C example: their coordinates use different origins.
Screen and controls
| Display | Meaning |
|---|---|
| One blinking error sprite | Invalid configuration or no responding device |
| Two blinking error sprites | Session/room could not be opened |
| Three blinking error sprites | Link/session failed |
| One sprite blinking in the waiting phase | Waiting for the other participant |
| Two moving squares | Local and received remote state |
Use the D-pad to move. Reset after an error; the minimal demo has no exit menu.
Integration pattern
while_waiting(int frames) calls bn::core::update() for each requested
frame. The game loop calls cf_poll() once, then advances Butano once.
The SDK header provides C linkage; no additional extern "C" wrapper is needed.
To add the core to another Butano project:
SOURCES := src vendor/canoflash-sdk/src
INCLUDES := include vendor/canoflash-sdk/include
Compile canoflash.c once. See Integration
for serial-port ownership, interrupt effects and frame-rate-dependent polling.
Scope
This demo sends normal position state only. It has basic status handling, not a complete recovery or authoritative-state protocol. The lobby adds room selection and UI; Reliable events explains the event channel.