Question

Calculate the shortest time-out period available with the cop and show the register settings needed.

a) Timer overflow
b) Interrupt latency
c) Clock frequency
d) System clock accuracy

Answer 1

To calculate the shortest time-out period for a microcontroller's timer, consider factors like timer overflow, interrupt latency, clock frequency, and system clock accuracy. The shortest period is set by configuring the timer to its highest frequency and minimum counting value, keeping in mind processor interrupt response time and clock precision.

Step-by-step explanation:

To calculate the shortest time-out period available with a timer/counter peripheral of a microcontroller (COP often refers to 'Computer Operating Properly' watchdog timer), you need to consider several factors:

• Timer overflow: This is when the timer counts to its maximum value and resets to zero. The shortest time-out period will occur at the smallest count that causes an overflow.
• Interrupt latency: This is the time taken for the processor to stop its current task and start the interrupt service routine. It should be added to the timer overflow time to get the total time-out period.
• Clock frequency: The speed at which the timer increments. A higher clock frequency allows for a shorter time-out period.
• System clock accuracy: This affects the precision of the time-out period but does not directly control its length.

To set the shortest time-out period, you would:

1. Configure the timer to its highest clock frequency setting.
2. Set the timer to the minimum starting value from which it overflows.
3. Take into account the interrupt service routine and the system clock accuracy in your calculations.

The actual register settings will depend on the specific microcontroller being used. Refer to the microcontroller's datasheet for exact bit settings for time-out configuration.