RC Car

To control the motor driver of the RC car we set up four control registers on the peripherals embedded in the micro controller. Each control register is assigned to either clockwise or counter clockwise for motor A and B. The control registers are activated by writing a high digital signal in the code to activate a certain direction of the motor. The PWM peripheral sends a PWM signal, with a certain duty cycle, to the enable pins on the motor driver to control the speed of each motor. Therefore, depending on the user input on the wireless controller the RC car moves in the direction desired.

For the wireless controller, we needed to analyze the receiver signals when the joysticks were being moved by the user. We first observed the signal for forward and reverse using an oscilloscope. We found that the output signal on the receiver is a PWM signal that adjusts the duty cycle when the joysticks are moved. Therefore, we realized that we needed to identify these thresholds on the micro controller and then output the correct signals to the motor driver.

To correctly observe the input signals on the micro controller we needed to use a timer module to measure the duty cycle on each input signal. The two pins we created for the wireless controller input signals were gas and turn. In our code we used a multiplexer to quickly transition between reading both signals to have an accurate response on the car. The interrupts we implemented are designed to measure the amount of time of each duty cycle to properly observe the signals. Once we figured out the correct thresholds for the correct directions in the PWM duty cycles we created conditional statements to activate the corresponding motor and direction. Overall , the RC car project result was a success and the car move accurately with the wireless controller.