| |
| Problem Definition |
| ------------------ |
| The task is to write a user interface module for an embedded device. |
| |
| Interrupts: |
| * The user interface is responsible for initializing the display. |
| * The user interface will register an interrupt handler for GPIO input 2 (a |
| push button). |
| * It will be possible to register a callback function for button presses. |
| * When there is no callback function set the irq handler will increment a |
| missed irq counter. |
| * When the interrupt occurs the handler will schedule or execute the button |
| press callback if there is one registered. |
| Output: |
| * Tasks can write messages to the user interface to be output on the display. |
| * The display is line oriented; when the last line of the display is written |
| the user interface is responsible for clearing the display. |
| * The display is 26 characters wide. Any string longer than that must be |
| truncated before being sent to the display. The string must be null |
| terminated and thus maximum 27 bytes long. |
| |
| * BONUS: Have the display be scrolling, i.e. when the display is full, the |
| previous lines must be shifted up one and the new line written in the bottom |
| line. |
