System Operation

Initially, the team that designed the system will be identified on the screen. "TEAM##$"$ will appear on the screen where ## are the two digits that identify the team number. When you press the S$1$ button, the name $($at least the first $6$ characters$)$ of the first member of the team will appear $($selected in alphabetical order of surnames$).$ If you continue pressing S$1,$ the names $($in alphabetical order of surnames$)$ of the other members of the team will continue to appear. After the last member, pressing S$1$ returns to identifying the team on the screen.

If$,$ when identifying the device number on the screen, you press S$2,$ the system will display the value $30$:$00$ on the screen, which corresponds to $30$ seconds. To do this, the four characters on the far right of the screen will be used. The counter will remain at that value until the S$1$ button is pressed. At that moment the display will show the time decreasing until it reaches $00$:$00.$ Each time one second passes the state of the heart symbol on display will be reversed. Each time you press the S$2$ button the Launchpad will invert the green LED state. When you start the program execution, both the heart and the green will be off. Each time the S$2$ button is pressed, the value of the counter on the display will be recorded. When the countdown reaches $00$:$00$ the system will remain in that state. When you press $51,$ CLICK$1$ will appear on the screen. Pressing $$1$ again will display the value that was on the screen when S$2$ was first pressed. Pressing S$1$ again will cause CLICKN to appear on the screen where N is the count of clicks that were made. For example, if $5$ clicks were made within $30$ seconds $($assume that there will never be more than $9)$ CLICKS will appear on the screen. Pressing $51$ again will display the value that was on the screen when the last CLICK occurred. Pressing S$1$ again will bring up DIFF on the screen. Pressing S$1$ again will display the difference in time between the first and last click on the screen. Pressing S$1$ again will return the system to the initial state.

Technical requirements

After system initialization and TEAM## appears in the display, the MCU will enter Low Power mode and will only exit it to attend to interrupt handling subroutines. When the processor has no tasks to perform, it will remain in Low Power mode. Readings of the status of the buttons will be carried out in response to interruption requests that they will generate. They will not be read using polling. All time controls in the system will be performed using the Timer AO timer. They will not be implemented through iterative structures.

The program has to be modular divided into subroutines. Each subroutine will end with a ret and, to the extent possible, will operate on values that it will receive through registers or the stack.

No jumps will be made from one subroutine to another using instructions other than calls. Failure to comply with the above implies a reduction of $20\%$ of the total score.