Part A: Clock
Use a timer interrupt to design a simple digital clock. This clock will count only minutes and seconds, and start at 00:00 every time your program starts. The display on the screen should read
mm:ss
The display should be kept on one line, and should only update once a second.
There will also be a ticking sound on the speaker once every second.
How should you design the clock? The specific method you use is up to you. Here are a few suggestions to get started:
• You can count interrupts to count seconds. For instance, if you use a 32 ms rate, one second is roughly 31 interrupts.
• When your clock reaches 59:59, reset the whole thing to 00:00 and start counting again.
• Also note that the speaker is on PORTA, pin 5.
Part B: Timer
Use the input capture to control the digital clock. In this part, there will be two switches to control the clock, one for starting the clock and one for stopping the clock. When the start button is pressed, it will reset the clock (set to Clock to 00:00) and enable the timer to start counting. On the other hand, when the stop button is pressed, it will disable the timer (stop the clock). It will be convenient to use the pushbutton switches on the FOX11 board to do this. One of the switches is already on PORTA and so can be used with the input capture feature. Your instructor will show you how to wire a PORTC switch over to PORTA for the second switch.