Suppose you are using SysTick in a busy-waiting method to periodically read a sensor value every 0.25 ms (i.e., initially, you are not using interrupts, but rather you are using a while busy-wait loop). a) Suppose you measured the microcontroller current and found it to be 200mA. If the microcontroller core voltage is 3.3V, what would be the microcontroller power consumption during the busy-waiting for the PWM method? Answer format: floating-point with at least two decimal places: Answer Watts. b) Suppose you were not happy with the power consumption of the busy-waiting method. Therefore, you decided to implement periodic interrupt with SysTick. You write a SysTick ISR handler consisting of 400 instructions long. Suppose the microcontroller CPI average is 1.5. How many clock cycles does it take to execute your ISR handler? Answer format: integer Answer c) How long doe it take to execute your ISR in microseconds if SysTick and the microcontroller are running at 48 MHz? Answer μs c) What percent of the time would the microcontroller spend executing your ISR? Answer%
Suppose you are using SysTick in a busy-waiting method to periodically read a sensor value every 0.25 ms (i.e., initially, you are not using interrupts, but rather you are using a while busy-wait loop).
a) Suppose you measured the microcontroller current and found it to be 200mA. If the microcontroller core voltage is 3.3V, what would be the microcontroller power consumption during the busy-waiting for the PWM method?
Answer format: floating-point with at least two decimal places: Answer Watts.
b) Suppose you were not happy with the power consumption of the busy-waiting method. Therefore, you decided to implement periodic interrupt with SysTick. You write a SysTick ISR handler consisting of 400 instructions long. Suppose the microcontroller CPI average is 1.5. How many clock cycles does it take to execute your ISR handler? Answer format: integer Answer
c) How long doe it take to execute your ISR in microseconds if SysTick and the microcontroller are running at 48 MHz? Answer μs
c) What percent of the time would the microcontroller spend executing your ISR? Answer%
d) Suppose with your periodic interrupts method, you can put the microcontroller in low-power mode when waiting for interrupts (i.e., when it is not executing the timer handler). Furthermore, suppose the low-power mode consumes only 20% of the full-power mode exhibited in part (a) (i.e., busy-waiting). Then, what would you expect for the new power consumption with the periodic interrupts method?
Answer format: floating-point with at least two decimal places: Answer Watts
e) What would be the percent power reduction from the busy-waiting method to the periodic interrupts method?
Answer format: floating-point with at least two decimal places: Answer %
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