A minimal paint application written for the ARM Cortex-M0 environment. Directional input moves a cursor across a memory-mapped canvas, while drawing and erasing operations update the active cell under strict low-level constraints.
Systems project
Assembly · Embedded Systems
ARM Cortex-M0 Paint
A cursor-based paint application implemented under low-level register and instruction constraints, with timer-driven input and canvas updates.
ARM AssemblyCortex-M0SysTickMemory-mapped I/O
Architecture view
Interrupt-to-pixel control flow
Each timer tick advances a small deterministic state machine from physical input to a bounded canvas write.
01SysTickPeriodic interrupt
02Read inputDirection · action
03State updateCursor · draw mode
04BoundsValidate coordinates
05CanvasMemory-mapped write
01 / ContextWhat I built
What I built
and why.
Without high-level data structures or an application framework, every state transition has to be explicit. Input timing, coordinate boundaries, address calculation and register use all need to stay correct at the same time.
A SysTick interrupt provides a predictable update rhythm. Each tick reads the current input, resolves the requested action, applies boundary checks and translates the cursor position into a canvas address before updating memory.
02 / Engineering
Key decisions
The choices that shaped the system—not only the technologies that appear in it.
Use a timer-driven loop
SysTick creates a consistent control cadence and keeps input handling independent from arbitrary busy-wait timing.
Guard coordinates first
Movement is validated before address calculation so the cursor cannot write outside the canvas region.
Keep state compact
Cursor position and drawing mode are represented with a small, explicit state that maps cleanly to registers and memory.
Technical toolkit
Built with
ARM AssemblyCortex-M0SysTickMemory-mapped I/O
03 / Reflection
What the project taught me
- Interrupt-driven control changes how state and timing must be reasoned about.
- Memory layout becomes part of the application design at the assembly level.
- Small boundary checks can protect an entire memory region from invalid writes.
This page uses a system diagram to document the current technical structure. Product screenshots and experiment outputs can be added here as each project evolves.