There are several ways to calculate the pulse width of a digital input signal. One method is to directly read the input pin and another method (more efficient) is to use a timer and pin change interrupt. Function startTimerl() starts Timerl with a count of zero and function stopTimerl()
stops Timerl and returns the count since it was started. An input signal is being received on PC4 that comes from an ultrasonic sensor. The ultrasonic sensor produces a negative pulse whose width is proportional to the distance from the object in front of the sensor as per the following formula: Distance (in cm) = 2 + PulseWidth where PulseWidth is in milliseconds. The pulse width is not known beforehand and it is the job of the ISR to determine the pulse width.
Write a C function that waits for the negative pulse to start (i.e, goes to logic zero) and count the number of milliseconds until the negative pulse has ended (goes back to logic one) and returns the distance in centimeters as an unsigned integer.
Write an ISR that is executed when input PC4 changes from low to high or high to low. Assume the interrupt has been setup properly and any change (1-> 0 or 0->1) on pin PC4 will cause the ISR(PCINT11_vect) to be executed. Your task is to write the body of the ISR(PCINT12_vect). Once the ISR detects that a negative pulse has
been received, it should find the pulse width and calculate the distance and then write the distance in the non-volatile global variable called distanceDouble (of type
double). You can assume that the maximum width of the pulse to be received is less than the time taken to overflow the timer and therefore the timer will not overflow while waiting for the pulse to complete. Assume that Timerl has been setup properly and two functions have been already written, namely startTimerl() and stopTimer1(). Note that you don't need to setup the timers and you don't need to write the code for startTimer10 and stopTimerl 0. Each count of the timer corresponds to 1 ms.
4. Write a C function waitForPulses(unsigned char N, pinNum) where N is the number of pulses to wait for. The function simply waits for N pulses to appear on PINB, pin number pinNum. For example, waitForPulses(5, 2) means wait for 5 pulses to occur on PB2.. (20 points)
An analog distance sensors is to be connected to an Arduino Uno R3. The sensor requires 5V and GND to operate and gives a single analog output (Doot) in the range 045V. The voltage is related to (not as cousins) the distance according to the equation: Distance (in cm) =11 x V + 4. Write a C function to keep the robot away from objects by at least 8 cm. Use the function setMotors(LeftMspeed, RightMspeed) to set the speed of left and right motors. The speed a number between -100 to 100. When both motor speeds are positive (robot moves forward) and when both motor speeds are negative (robot moves backward). Assume sensor is positioned such that it detects objects in front of the robot. (20 points)
Write a C program that waits for a button connected to PD2 to be pressed and released, de-bounces both press and release, blinks an LED connected to PD3 once, waits for the button to be pressed and released for the second time, blinks the LED twice, and so on. Each time the button is pressed, the number of blinks is incremented. This should go on indefinitely.