F16: AutoNav

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Project Title

AutoNav - The Autonomous RC Car

AutoNav RC Car(Controller View)
AutoNav RC Car(Sensor View)


This project report describes an attempt to develop an autonomous RC car which navigates from a source point to destination avoiding any obstacles in between. The project was divided into five modules namely Motor & Input/output Controller, Sensor Controller, Geo Controller, Communication Bridge & Android Controller and Master Controller, each performing specific set of tasks. Each of the five modules were established using SJOne Boards. Communication between all the five modules was established using CAN Bus.

  • Motor & I/O Controller - This controller was responsible for driving Brushless DC Motor interfaced through ESC, driving the stepper motor for steering and displaying the status of the RC car (speed, obstacle distance etc.) on the LCD.
  • Sensor Controller - This controller was responsible for obstacle detection and avoidance, interfacing done with Ultrasonic Ping Sensors.
  • Geo Controller - This controller focused on providing orientation (heading and bearing) and navigation route to the car.
  • Communication Bridge & Android Controller - Co-ordinates for navigation were provided by this controller using an android application. Communication was established via Bluetooth.
  • Master Controller - This controller was responsible for collecting the data from all the controllers, develop and implement obstacle avoidance algorithm to guide the car towards the final destination.

Objectives & Introduction

The main objectives of this project include:

  • To develop an autonomous RC Car.
  • To navigate from a set source to destination.
  • To avoid any obstacles in between.
  • To establish all communication between controllers via CAN bus.

The following peripherals of LPC 1758 were used to establish communications:

  • CAN Peripheral: Communicate between all the controllers on a common CAN bus.
  • UART Peripheral: Communicate between GEO Controller and GPS module, Bluetooth controller and Bluetooth module.
  • GPIO: Communicate between sensors and sensor controller.
  • PWM: Vary the speed of Brushless DC motor and Stepper motor via ESC interfaced through Motor Controller.

The block diagram below gives an overview of the various peripherals used:

Peripheral block diagram

Team Members & Responsibilities

Sensor Controller:

  • Vishwanath Balakuntla Ramesh

Motor & I/O Controller:

Bluetooth (Communication Bridge) & Android Controller:

  • Sucharitha
  • Karthikeya Rao G V

Geographical Controller:

  • Arpita Ramanath
  • Veena Manasa Kanakamalla

Master Controller:


Consolidated Team Schedule

SI No. Start Date End Date Task Status Actual Completion Date
1 09/13/2016 09/27/2016
  • *Motor - Research and order RC car and additional batteries
  • *Sensor - Researching and understanding various sensor requirements for a self driving vehicle.
  • Shortlisting the sensors suitable for our application.
  • *GPS - Research and order GPS and Compass module.
  • *Bluetooth - Learning and Getting familiarized with Android SDK, Java, Bluetooth API and Google Maps API.
  • *Master - Understanding the working of CAN Communication and research on obstacle avoidance and navigational algorithm.
Completed 09/26/2016
2 09/27/2016 10/11/2016
  • *Motor - Understand and implement PWM concepts to drive brushless DC motor and servo motor of the RC car. Set PWM frequency range for varying duty cycle.
  • *Sensor - Reading datasheets of shortlisted sensors, Understand pros and cons of each sensor. Make an Order.
  • *GPS - Get familiar with data sheets of both modules. Identify relevant pins and understand the module schematics (GPS and IMU).
  • *Bluetooth - Buttons and text insertion on the app. Ex: switch on and off Bluetooth, getting longitude latitude values on the phone Placement of route markers on Google maps between source and destination.
  • *Master - Developing the required control messages to be used in CAN Bus for communication between different controllers.
Completed 10/11/2016
3 10/12/2016 10/18/2016
  • *Motor - Interfacing Brushless DC Motor & Servo Motors to SJ one board - implement duty cycles using provided PWM library. Use terminal commands to test basic functionality like drive straight, turn left or right.
  • *Sensor - Write sample code for sensors and experiment with sensor output(filtering).
  • *GPS - Interface GPS and Compass modules to SJOne board using UART. Test functionality of each module.
  • *Bluetooth - Establishment of communication between Bluetooth and the phone application by sending and receiving the values Routing markers display on google maps for a straight line between source and destination.
  • *Master - Establishing CAN communication between master controller, sensor controller and Bluetooth controller with addition of handling MIA in all the controllers.
Completed 10/20/2016
4 10/19/2016 10/30/2016
  • *Motor - Implement CAN bus communication - setup CAN Msg ID acceptance filters, integration with sensor data and Master Controller.Develop basic obstacle avoidance algorithm. Testing of obstacle avoidance algorithm in real time.
  • *Sensor - DBC file implementation to establish CAN communication with Master controller.
  • Collaborate with Motor I/O team to achieve basic obstacle avoidance.
  • *GPS - Calibrate GPS and Compass modules. Write code to parse raw Compass and GPS readings. Test calibration of the modules.
  • *Bluetooth - Interfacing Bluetooth module to SJ One board through UART and sending and receiving data between them.
  • *Master - Master Controller should acquire obstacle range sensor data from sensor controller, control commands from Bluetooth controller.
Completed 11/01/2016
5 10/31/2016 11/08/2016
  • *Motor - LCD interfacing to display messages from required controllers. DBC File Implementation and integrating data structures generated from auto gen code.
  • *Sensor - Identify and implement a mechanism to avoid sensors from interfering with each other.
  • Add multiple sensors to the car and work on synchronization between them to achieve more precise obstacle avoidance.
  • *GPS - Establish CAN communication from Geo controller to Master controller. Send CAN messages of latitude, longitude, heading and bearing from Geo controller to master to set destination.
  • *Bluetooth - Receive commands from SJ One to android application and test if right data is being sent.
  • *Master - Master controller should send directional control messages to motor controller to control the car to its desired path. Implement and test a simple obstacle avoidance algorithm on to the Master controller.
Completed 11/12/2016
6 11/09/2016 11/27/2016
  • *Motor - RPM sensor interfacing to develop Motor Feedback Control loop. Up/down hill driving testing in real world.
  • *Sensor- Design and implement the circuit and software for Car's battery voltage monitoring and determining the State of charge(SOC).
  • Design and implement the software to read light sensor values and Tilt (angle of the car) sensor values.
  • *GPS - Test destination setting, navigation and synchronization with Master controller and Android app.
  • *Bluetooth - Testing the routing path and the basic testing of the application.
  • *Master - Master controller has to acquire coordinates from Geo controller to be used for navigational algorithm. Also get heading, bearing and speed information from Geo-controller.
Completed 11/29/2016
7 11/27/2016 12/15/2016
  • *Motor - Integration with RC Car controllers as one system. Testing, debugging and optimization.
  • *Sensor - Integration testing with Master Controller and other boards.
  • Optimize the code, Finalize the operation (validate correctness) & Documentation.
  • *GPS - Integrate Geo controller with the entire system. Test and debug code.
  • *Bluetooth - Integration Testing and Final testing after integration of all the modules on the car.
  • *Master - Implement and test navigational algorithm. Integrate navigation and avoidance algorithm and perform final testing.
Completed 12/18/2016

Parts List & Cost

Item# Part Description Vendor Qty Cost
1 RC Car RChobby Explosion 1 $190
2 RC Car Battery Amazon 1 $27.29
3 CAN Transceiver Texas Instruments 15 Free
4 M-F,F-F,M-M Jumper Wires Amazon 120 7.97
5 Printed Circuit Boards Amazon 1 $9.72
6 Ultrasonic Parallax Ping Sensor Fry's Electronics 3 $98.85
7 9 DOF Razor IMU module SparkFun 1 $74.95
8 Bluetooth Module Amazon 1 $9.99
9 GPS Sensor Adafruit 1 $44.38
10 Black/White line detection sensor - RPM sensor Amazon 1 $10.10
11 SJOne Boards From Preet 5 $400
12 LCD 4D systems 1 $111

DBC File Implementation

DBC files are widely used to define the system of CAN messages and their constituent signals. This allows CAN data to be accessed in terms of human-usable signal values, with different data types and scaling, instead of just raw message bytes. Below is the DBC file that we implemented in our project.


NS_ :

 SG_ killSwitch : 0|1@1+ (1,0) [0|0] "Stop=1" MOTOR

 SG_ BLUETOOTH_STOP_CMD_signal : 0|1@1+ (1,0) [0|0] "Stop=1" DRIVER

 SG_ Motor_Sync : 0|1@1+ (1,0) [0|0] "MotorSync=1" DRIVER

 SG_ Geo_sync_cmd : 0|1@1+ (1,0) [0|0] "GeoSync=1" DRIVER
 SG_ BLUETOOTH_SYNC_CMD_signal : 0|1@1+ (1,0) [0|0] "BluetoothSync=1" DRIVER
 SG_ Sensor_Sync : 0|1@1+ (1,0) [0|0] "SensorSync=1" DRIVER,MOTOR,BLUETOOTH
 SG_ Sync_Miss_Info : 0|8@1+ (1,0) [0|0] "ErrorMsgType" MOTOR
 SG_ Sync_Miss_Info : 0|1@1+ (1,0) [0|0] "DriverSync=1" MOTOR,BLUETOOTH,SENSOR,GEO
 SG_ steer : 0|8@1+ (1,0) [0|0] "DirectionType" MOTOR    
 SG_ speed : 8|8@1+ (1,0) [0|0] "SpeedType" MOTOR  
 SG_ Rps_Sensor : 0|8@1+ (1,0) [0|0] "RotationsPerSecondENum" DRIVER,BLUETOOTH
 SG_ Rps_Value : 8|8@1+ (1,0) [0|0] "RotationsPerSecondValue" BLUETOOTH,DRIVER

 SG_ Sensor_Sonar_Front : 0|8@1+ (1,0) [0|0] "FrontDistance" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Sonar_FrontRight : 8|8@1+ (1,0) [0|0] "FRightDistance" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Sonar_FrontLeft : 16|8@1+ (1,0) [0|0] "FLeftDistance" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Sonar_Back : 24|8@1+ (1,0) [0|0] "BackDistance" DRIVER,MOTOR,BLUETOOTH
 SG_ Geo_latitude : 0|32@1+ (0.000001,-90.000000) [-90|90] "latitude" DRIVER,BLUETOOTH,MOTOR
 SG_ Geo_longitude : 32|32@1+ (0.000001,-180.000000) [-180|180] "longitude" DRIVER,BLUETOOTH,MOTOR

 SG_ Geo_heading : 0|29@1+ (0.000001,0) [0|360] "" DRIVER,MOTOR
 SG_ Geo_bearing : 29|29@1+ (0.000001,0) [0|360] "" DRIVER,MOTOR

 SG_ Bluetooth_CurrWaypoint : 0|5@1+ (1,0) [0|0] "CurrentWaypointNumber" DRIVER,GEO
 SG_ Bluetooth_NumWaypoint : 5|5@1+ (1,0) [0|0] "NumberOfWaypoints" DRIVER,GEO

 SG_ Bluetooth_latitude : 0|32@1+ (0.000001,-90.000000) [-90|90] "latitude" DRIVER,GEO
 SG_ Bluetooth_longitude : 32|32@1+ (0.000001,-180.000000) [-180|180] "longitude" DRIVER,GEO

 SG_ BLUETOOTH_START_CMD_signal : 0|8@1+ (1,0) [0|0] "" DRIVER
 SG_ Sensor_Battery_Voltage : 0|8@1+ (0.1,0) [0|0] "Volts" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Battery_SOC : 8|10@1+ (0.1,0) [0|0] "Percent" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Light : 18|10@1+ (0.1,0) [0|0] "LightPercentValue" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Tilt_X : 28|12@1+ (0.1,0) [0|0] "TiltValueX" DRIVER,MOTOR,BLUETOOTH
 SG_ Sensor_Tilt_Y : 40|12@1+ (0.1,0) [0|0] "TiltValueY" DRIVER,MOTOR,BLUETOOTH
 SG_ Driver_Test_Msg : 0|8@1+ (1,0) [0|0] "" MOTOR,GEO,SENSOR,BLUETOOTH

 SG_ Motor_Test_Msg : 0|8@1+ (1,0) [0|0] "" DRIVER,GEO,SENSOR,BLUETOOTH
 SG_ Sensor_Test_Msg : 0|8@1+ (1,0) [0|0] "" DRIVER,MOTOR,GEO,BLUETOOTH
 SG_ Geo_Test_Msg : 0|8@1+ (1,0) [0|0] "" DRIVER,MOTOR,SENSOR,BLUETOOTH
 SG_ Bluetooth_Test_Msg : 0|8@1+ (1,0) [0|0] "" DRIVER,MOTOR,GEO,SENSOR
CM_ BU_ DRIVER "The DRIVER controller driving the car";
CM_ BU_ MOTOR "The motor controller of the car";
CM_ BU_ SENSOR "The sensor controller of the car";
CM_ BU_ GEO "The geo controller of the car";
CM_ BU_ BLUETOOTH "The bridge controller of the car";
CM_ BO_ 100 "Sync message used to synchronize the controllers";

BA_DEF_ "BusType" STRING ;
BA_DEF_ BO_ "GenMsgCycleTime" INT 0 0;
BA_DEF_ SG_ "FieldType" STRING ;

BA_DEF_DEF_ "BusType" "CAN";
BA_DEF_DEF_ "FieldType" "";
BA_DEF_DEF_ "GenMsgCycleTime" 0;

BA_ "GenMsgCycleTime" BO_ 500 10;
BA_ "FieldType" SG_ 180 steer "steer";
BA_ "FieldType" SG_ 180 speed "speed";
BA_ "FieldType" SG_ 181 Rps_Sensor "Rps_Sensor";
BA_ "FieldType" SG_ 190 Sensor_Sonar_Front "Sensor_Sonar_Front";
BA_ "FieldType" SG_ 190 Sensor_Sonar_FrontRight "Sensor_Sonar_FrontRight";
BA_ "FieldType" SG_ 190 Sensor_Sonar_FrontLeft "Sensor_Sonar_FrontLeft";
BA_ "FieldType" SG_ 190 Sensor_Sonar_Back "Sensor_Sonar_Back";

VAL_ 190 Sensor_Sonar_Front 3 "far_f" 2 "mid_f" 1 "near_f" 0 "danger_f" ;
VAL_ 190 Sensor_Sonar_FrontRight 2 "far_fr" 1 "mid_fr" 0 "near_fr" ;
VAL_ 190 Sensor_Sonar_FrontLeft 2 "far_fl" 1 "mid_fl" 0 "near_fl" ;
VAL_ 190 Sensor_Sonar_Back 2 "far_b" 1 "mid_b" 0 "near_b" ;
VAL_ 180 steer 4 "right" 3 "sright" 2 "sleft" 1 "left" 0 "straight" ;
VAL_ 180 speed 4 "brake" 3 "reverse" 2 "normal" 1 "slow" 0 "stop" ;
VAL_ 181 Rps_Sensor 2 "high" 1 "equal" 0 "low" ;

Design & Implementation

The flow of data from the beginning is shown by the diagram below.

System Block Diagram


Assuming the car would be given the necessary connections and be powered up to navigate, we would give the first signal to start the car from the Bluetooth device by sending a start signal of "1". Once the Start signal is received by the Master controller, it would receive the signals from the sensors and the GPS as well. Based on the data from all these systems, Master controller decides the command to be given to the Motor controller. Motor on receiving the instructions from the Master would move in a particular direction suggested by Master. Motor would also revert the path in which it is going, RPM values to Master, Bluetooth and LCD display over the CAN. Meanwhile the Bluetooth would be fetching the messages from the CAN and would filter out on the messages by their ID's and later send the required signals such as GPS and RPM values to the Android device, which is displayed to the user in their respective text boxes.


Below is the screenshot of messages from all five controllers on the CAN Bus, as seen in from a PCAN dongle, while testing the CAR after integration.

P-CAN Dongle

The PCAN dongle would be connected to RX-480 Port on the CAR and other end to a PC via USB.This would enable the user to view the CAN messages on the CAN Bus in real-time on the computer screen and would largely help to debug errors on all the controllers. BusMaster is the software used to decode the messages on the CAN bus.

Sensor Controller

Team Members:

Vishwanath Balakuntla Ramesh

The sensor controller is one of the main controllers in the car, which enables the obstacle avoidance feature. There are multiple sensors available in the market, which can used to detect obstacles. The sensor controller may use IR sensor, ultrasonic sensors, sonar, lidar etc,. In our case w make use of Parallax ping sensor due to following reasons:

1. Ease of usage: Same pin for Echo and input pulse. 2. High S/N ratio: The signal to noise ratio is too high. The sensor does not abruptly issue any spike in its signal. More reliable and stable.

Hardware Design

We used 3 Parallax Ping ultrasonic distance sensors for obstacle detection and avoidance. Non-contact distance can be measured from about 2 cm (0.8 inches) to 3 meters (3.3 yards).

The PING sensor works by transmitting an ultrasonic burst and providing an output pulse that corresponds to the time required for the burst echo to return to the sensor. By measuring the echo pulse width, the distance to target can easily be calculated.

Three sensors were placed in front (front_left, front_center, front_right).

Parallax ping sensor

Hardware Interface

Three parallax ping sensors are used (front, left and right). As shown above, in the hardware design of parallax ping sensor, VCC pin of all the three sensors is connected to 5V, GND is connected to ground and SIG of all the three sensors is connected to P2.0, P2.1, and P2.2 of SJ One board.

Parallax Ping Sensor Operation

Software Design

Sensor Fields and Ranges
Sensor Controller Tasks
Task Name Purpose
Period Init Enable and initialize LPC timer, Initialize CAN, rising and falling edge of GPIO Interrupt
Periodic 1Hz Callback Check can bus off
Periodic 10Hz Callback Get and Send Sensor Data

Sensor_Sonar_Front_E calculate_range_front(double distance)
		return danger_f;

	else if(distance<180)
		return near_f;

	else if(distance<250)
		return mid_f;

		return far_f;

Sensor_Sonar_FrontRight_E calculate_range_frontRight(double distance)
		return near_fr;

	else if(distance<200)
		return mid_fr;

		return far_fr;

Sensor_Sonar_FrontLeft_E calculate_range_frontLeft(double distance)
		return near_fl;

	else if(distance<200)
		return mid_fl;

		return far_fl;

void start_trigger(GPIO trigger)


Sensor Controller Flow Diagram

Motor & I/O Controller

Team Members:

Sameer Saran
Jaswanth Bhimanapalli

Hardware Design

Block Diagram for Motor

Hardware/Software Interface

I/O Interface - LCD

The LCD is used to display some of the features to its application in our project.The sensor, GPS and current coordinates are displayed on LCD. The LCD we bought is from 4D systems and is very convenient and efficient to use. It has its own software which enables us to work in 4 different modes. We chose the mode which gave us different tools to build the compass, buttons and the angulometer. Bluetooth to serial converter is used to program the LCD with the software. We used the tools (that came with the LCD Module), to picturize our LCD screens. We loaded the program into LCD's memory card. The program that we burned on LCD will use the data bytes we send from our microcontroller and will print those bytes appropriately on different elements that we had created. For example, there are 360 degrees values to show on angulometer. The microcontroller will give a value from 0-360 based on the CAN frame which consists of car speed, heading and bearing values broadcasted by the Geo controller. In this way, almost every parameter being exchanged on the CAN bus of the car is displayed.

The following is the link to the main page of the LCD. It contains everything you need to know to run this LCD and run it to the highest feature. It has the datasheet as well as the info regarding the software too. Go through the software datasheets as well as we will need that software to run the LCD initially. The LCD accepts any data from our microcontroller only if it is programmed that way by the software. http://www.4dsystems.com.au/product/uLCD_32PTU/ Next link is to the to the collection of go through materials for each every object the LCD uses. http://old.4dsystems.com.au/appnotes.php

Now, if you have gone through the software datasheets, you will be already have accustomed with the software and its fun too. Select your tool accordingly your requirement. Be creative. We needed to show magnetometer values, from 0 to 360 in order to debug whether the compass is pointing towards north exactly or not. So we used an angularometer under the Gauges tab. It will have all the properties associated with the object. You can test each of them. Now, the data sent from the microcontroller will be directly printed on the LCD to its position on the angulometer. In this way, we can easily know the direction of True North with the help of LCD. Alon with this there are some strings used on LCD which shows longitude, lattitude, etc. This string is also sent from the microcontroller. When you are done with the tools, put a memory card with a maximum of 2 GB of memory into your LCD and connect it serially to your PC. USB to serial converter is to be used here. Burn the software image onto your LCD. At this point, your LCD is programmed to show all the images and the tools and is ready to accept all the data from the controller and print them on itself. So now we have got to do, is only connect the controller with LCD and send data bytes with help of UART.

Below are the snaps of the LCD Screens:

LCD Screen 1
LCD Screen 2
LCD Screen 3
LCD Screen 4
LCD Screen 5
LCD Screens Table
Screen No. Description
1 Welcome Screen
2 Displaying the menu
3 Displaying Sensor data
4 Displaying motor data
5 Displaying data to debug along with GPS data
LCD Flowchart

Motor Control Hardware/Software Interface


Motor/IO Controller Tasks
Task Name Purpose
Period Init Initializing CAN bus, Motor, Interrupt for Motor Feedback and UART for LCD
Periodic 1Hz Callback Displaying data on LCD and checking for CAN bus off
Periodic 10Hz Callback Interpreting data from Master controller, driving car, calculating RPM
Motor Control Flowchart

Brushless DC Motor

Our car came with 3650 Brushless inrunner motor, 2080KV with 60A ESC(with Reverse). This motor has the power to run the car at a maximum speed of the 35mph.

The table below contains information about PWM (duty cycle) given to the motor and the corresponding speed of the car on a flat surface.

S.R. Duty Cycle Speed Control
1 7.5 Stop
2 7.77 Slow
3 7.81 Normal
4 7.30 Reverse
5 5.5 Brake

Table3: DC Motor Duty Cycle v/s Speed Control

CMPE 243 Autonav Brushless Motor.jpeg
Brushless DC Motor

DC motor is controlled with the help of three wires coming out of the ESC. These wires are VCC, GND and Speed control. The VCC line is not used as required voltage is directly given to the motor through a battery, via ESC. The GND line and Speed control lines are connected to the ground and PWM pin of SJOne board.

S.R. ESC Wire Pins SJOne Board Pins
1 Vcc -
3 Speed Control P2.1

DC Motor Pin Connections

To drive the DC motor, we are using pwm2 i.e. pin P2.1 of the SJOne board. We are using the in-build PWM generation function which requires two parameters, one is pin being used and the other being the frequency. To set the required duty cycle, the in-build set function is used.

Motor Feedback

Initially we used to calculate feedback at 1Hz using one magnet and a telemetry sensor and if the current RPM was less than required RPM then we used to switch to the higher hard coded PWM value, But since the DC motor was dependent on the battery's state of charge. We had to redesign the Motor Feedback, we added more magnets so that we get enough data so that we can react at a faster rate of 10Hz. To make the DC motor's speed independent of state of charge and dependent only on RPM we changed the Motors's Algorithm.

Below is the Code snippet of DC Controller

void drive_DC(speed_E speed,int rpm)
        //Set DC to Reverse PWM Value
	else if (speed==brake)
	//Set DC to Brake PWM Value	
	else if (speed == stop)
	//Set DC to Stop/Idle PWM Value

		if(DC Value id with in safe range)
			//If current RPM is greater then Required RPM then Reduce Speed
			else if(rpm<ReqRPM)
			//If current RPM is lesser then Required RPM then Increase  Speed

			else if(rpm==ReqRPM)
		        //If current RPM is equal to required RPM the maintain same Speed


Servo Motor

Our car came with a waterproof digital servo motor. This motor works without ESC. We can directly control this motor by giving PWM signal from our SJOne board. The below table contains information about PWM (duty cycle) given to the motor and the corresponding turns taken by the car.

S.R. Duty Cycle Turn
1 8.5 Hard Left
2 8 Slight Left
3 7.5 Straight
4 6.5 Slight Right
5 6.0 Hard Right

Servo Motor Duty Cycle v/s Turn

CMPE243 F16 Autonav Servo-Motor.jpg
Servo Motor

Servo motor is controlled with the help of three wires coming out of the servo motor. The wires are VCC, GND and Direction control. The VCC is connected to the 3.3v. GND and direction control are connected to the ground and pwm pins of SJOne board.

S.R. Servo Motor Pins SJOne Board Pins
1 Vcc Vcc
3 Direction Control P2.0

Servo Motor Pin Connections

We control the Servo motor using pwm1 i.e. pin P2.0 of the SJOne board. We configure the PWM pin using an in-build function which requires two parameters, one is the pin that we are using and the other is the frequency of the pwm. To set the duty cycle, in-build set function is used in which we are passing the duty cycle at which we want servo motor to work.

Motor cnt1.png
Servo Motor Connector

class MotorCtrl : public SingletonTemplate<MotorCtrl>
		MotorCtrl() : steerServo(PWM::pwm1),driveDc(PWM::pwm2)
		void set_servo(float value) {steerServo.set(value);}
		void set_dc(float value){driveDc.set(value);}
		friend class SingletonTemplate<MotorCtrl>;

		PWM steerServo;
		PWM driveDc;


#define MotorCtrl MotorCtrl::getInstance()

Bluetooth and Bridge(Android) Connections

Team Members:

Sucharitha Sirigreddy
Karthikeya Rao G V

This section includes high level implementation details regarding the Android app connectivity with the Bluetooth module of the RC car. It gives a overview of building the android app, communication between the Bluetooth and Android app on a mobile device, and routing mechanisms during the navigation.

Bluetooth Controller Pin Connections

Node A Source Node A Pin Node B Source Node B Pin Description
Power Supply 3.3V SJOne Board 3V3 SJOne Power
Power Supply GND SJOne Board GND SJOne Ground
CAN Transceiver CAN Tx SJOne Board P0.1 (Tx) SJOne - CAN Tx
CAN Transceiver CAN Rx SJOne Board P0.0 (Rx) SJOne - CAN Rx
Bluetooth Module TXD SJOne Board RXD3 SJOne RX3- Bluetooth module TXD
Bluetooth Module RXD SJOne Board TXD3 SJOne TX3- Bluetooth module RXD
Bluetooth Module Bluetooth module VCC(3.3V) Power Supply 3.3V Bluetooth module - Power supply 3.3V
Bluetooth Module Bluetooth module GND Power Supply GND Bluetooth module - Power supply GND

Below attached is the image of the Bluetooth Module HC-06.

Bridge Controller Design

Hardware Interface

Below is the representation of the bridge communication.

Bridge Controller Design

Hardware Interface between the Bluetooth controller and the car system has been wired through the CAN bus. P0.1 is connected to CAN Tx and P0.0 is connected to CAN Rx, where communication between the Bluetooth module and other modules happen. RXD and TXD pins are connected to Bluetooth HC-06 to enable communication between the Android mobile device and the Bluetooth module. Power supply and Ground pins to SJone board i.e Bluetooth module is provided by battery, which would power up all the SJone boards. Power to the HC-06 module is given by the SJone Bluetooth board 3.3V and GND pins. Thus enabling the Interface between Bluetooth module and the other controllers.

Software Design

Software interface between HC-06 and Android device is enabled via Bluetooth transmission and reception.

Below attached is the image showing the Android Application Development.

Stages of Android Application Development

Initially we developed the Application with just Enable and Disable Bluetooth Buttons, after which we added the Start and Stop Signals Button. Start and Stop buttons were given the functionality to send "1" and "0" respectively. In the next phase, we integrated the application with Google maps with few more buttons and obtained our location from the Google maps and cell phone GPS and marked our location on the App screen. In the Final phase we were able to display the application with all the values which we received from the Bluetooth controller, which includes RPS and Locations.

Below diagrams represent the different app screens in the selection sequence.

Pairing with Bluetooth
Destination set
Displaying CAN data

In the above image, we initially turn on the Bluetooth device. Once done, we set up the start and destination on the map, marked as red and green flags respectively. Clicking on the Start signal would enable the Car to receive the Signals Route button would send out the way points to the Bluetooth controller and the Master sending the signal to move the car in the way points direction.

Flow Chart:

Flow Chart of the Bluetooth and Android design is as follows.

Android and Bluetooth Controller Flow Chart

Android-Bluetooth Controller Button's Functionality Table

SI No. Button Functionality
1 BTON User is prompted to Turn on Bluetooth device on the phone. User can either "allow" or "deny" the request. Application won't work till the request is allowed.
2 START Sends string 1 over Bluetooth channel to indicate to to Master Controller to start of car.
3 STOP CAR Sends string 0 over Bluetooth channel to indicate to Master Controller to stop the car(Wireless Kill switch).
4 BTOFF Turns off the Bluetooth of the Android device.
5 LOC Places a marker on Google Map based on cars Latitude and Longitude received from the GEO module on the car.
6 ROUTE Send route from source to destination selected on map after filtering way-points to the Bluetooth Controller and to GEO controller there on.


BT connection establishment

Through the Android application the Bluetooth would be paired with HC-06 module on click of BTon button, which turns on the Bluetooth on the android phone and connects to Car’s HC-06 Bluetooth device. Post which, we would send a start signal from the app, which would sync and start the car. This signal is encoded before sending from the android. This signal when received from the Bluetooth module, would decode and read the message and later encode and pass it on over the CAN to the Master.

Communication between BT and other controllers

BT Application and BT controller communicates over UART at 9600 bits/sec baud rate,as HC-06 operates at that baud rate.

Send data to Application

Bluetooth controller communicates with other controllers through CAN.Once BT App installed on mobile,App requests for BT permissions from user.Once allowed to access BT on the mobile phone, App can send and receive messages over UART.CAN messages received from other modules are decoded and the corresponding message is sent to BT application with the specified character sequence through UART. Ex:RPS value from the Motor controller is sent to Bluetooth controller is sent as "r" followed by "!" "<rps value>".IN this sequence "r" is the identification command for the rps value that is being sent from the motor and "!" is delimiter to indicate the app that the next characters are the received values from the motor.This characters are displayed in a text area on app under the heading RPM. Every time the app receives rpm value,the same is displayed on the text section assigned for the RPM on the app.Similarly Sensor,Geo controller sends right sensor value and geo co-ordinates respectively.These are displayed on the allocated text areas on the application.

Receive data from application

Based on the commands(button press on the application) send to the app,it will respond with the appropriate data.A thread starts running once START command on the application is pressed,this threads is alive till the application is closed.This is a way for the controller to know that Bluetooth connection is intact between BT app and controller.Any data sent to application is always listened through socket communication and the application responds if any command is programmed fro the received message. A circular buffer at the receiver part of the application is useful for the data to be received without corruption.Application sends data through socket communication at faster rate than that BT controller receive,hence buffer at the controller should be able to store the data received from application.

Sending route to SJone board

Route Button on the app would be initiated once we set the source and destination by 2 clicks on the maps in the app and start getting the location details from HC-06. Route Button ,on click would send the location from the car and send out next way points till the destination. The Kill switch is implemented as Stop Button, which sends of “0” signal, which is received by the Bluetooth and sent over the CAN Bus to master, to stop the Motor.

Code snippet to send rpm data to App
 if (dbc_decode_MOTOR_RPS(&motorrps, can_receive.data.bytes,&can_msg_hdr))

         char a[3] ={ 0 };
         sprintf(a, "%d",  motorrps.Rps_Value);
         u3.putChar('r', 0);
         u3.putChar('!', 0);
         u3.putline(a, 0);
         u3.putChar('!', 0);


Geographical Controller

Team Members:

Veena Manasa Kanakamalla
Arpita Ramanath

Hardware Design

System Block Diagram

SJ One board is interfaced to GPS module and IMU through UART.

Hardware Interface of GeoController

Geographical Controller Hardware Design Components

GPS Module

Adafruit MTK3339 GPS:

This GPS unit is interfaced via UART with build in antenna. The GPS provides latitude and longitude accurately up to 5-10 meters with a strong satellite fix with update rate of 10Hz. By default, the baud rate is 9600bps. Power usage for this module is 20mA during navigation.

The GPS module comes with following capabilities:

  • -165 dBm sensitivity, 10 Hz updates, 66 channels
  • 5V friendly design and only 20mA current draw
  • Breadboard friendly + two mounting holes
  • RTC battery-compatible
  • Built-in datalogging
  • PPS output on fix
  • Internal patch antenna + u.FL connector for external active antenna
  • Fix status LED

We chose this part because it provided the base functionality we needed along with many other functions that would be fun to play with and try to include in the project. The antennae options and voltage regulator were also very enticing. We get raw GPS "NMEA sentence" output from module. The most important NMEA sentences include the GGA which provides the current Fix data, the RMC which provides the minimum gps sentences information, and the GSA which provides the Satellite status data. We are filtering the data for RMC, Recommended Minimum, which will look similar to:

GGA- essential fix data which provide 3D location and accuracy data.

    GGA          Global Positioning System Fix Data
    123519       Fix taken at 12:35:19 UTC
    4807.038,N   Latitude 48 deg 07.038' N
    01131.000,E  Longitude 11 deg 31.000' E
    1            Fix quality: 
                  0 = invalid
                  1 = GPS fix (SPS)
                  2 = DGPS fix
                  3 = PPS fix
                  4 = Real Time Kinematic
                  5 = Float RTK
                  6 = estimated (dead reckoning) (2.3 feature)
                  7 = Manual input mode
                  8 = Simulation mode
    08           Number of satellites being tracked
    0.9          Horizontal dilution of position
    545.4,M      Altitude, Meters, above mean sea level
    46.9,M       Height of geoid (mean sea level) above WGS84
    (empty field) time in seconds since last DGPS update
    (empty field) DGPS station ID number
    *47          the checksum data, always begins with *

GPS Pin Connections

GPS Pin Connections

9 Degrees of Freedom- Razor IMU:

In our project, we used IMU module to get the heading of the device. The 9DOF Razor IMU provides nine degree of inertial measurement incorporates three sensors - an ITG-3200 (MEMS triple-axis gyro), ADXL345 (triple-axis accelerometer), and HMC5883L (triple-axis magnetometer). The outputs of all sensors are processed by an on-board ATmega328 and output over a serial interface. UART interface is used for interfacing with SJ One board and it is connected via UART3 with LPC board and is operated at 3.3V.


  • 9 Degrees of Freedom on a single, flat board:
    • ITG-3200 - triple-axis digital-output gyroscope
    • ADXL345 - 13-bit resolution, ±16g, triple-axis accelerometer
    • HMC5883L - triple-axis, digital magnetometer
  • Outputs of all sensors processed by on-board ATmega328 and sent out via a serial stream
  • Autorun feature and help menu integrated into the example firmware
  • Output pins match up with FTDI Basic Breakout, Bluetooth Mate, XBee Explorer
  • 3.5-16VDC input
  • ON-OFF control switch and reset switch

IMU Pin Connections

IMU Pin Connections

Hardware Interface

Geographical Controller H/W Interface

  • Below table shows the pin connections of GPS and IMU module with SJ One Board. Both the modules are interfaced with Controller using UART interface. The operating voltage of GPS and IMU is 5V.
Geographical Controller Pin Connections
Description Interface Port Used Controller Port
Supply Voltage N/A 5V power supply N/A
Ground N/A GND GND
GPS Module UART3
1 -> Rx
2 -> Tx
1 -> Tx P4.28
2 -> Rx P4.29
IMU Module UART2
1 -> Rx
2 -> Tx 
1 -> Tx P2.8
2 -> Rx P2.9

Software Design

Geographical controller uses two modules to get GPS data and heading. These are:

  • GPS module
  • IMU module


Geo Controller Tasks
Task Name Purpose
Period Init Initializing CAN bus, UART2 for IMU, UART3 for GPS
Periodic 1Hz Callback Checking for CAN bus off
Periodic 10Hz Callback Receiving and parsing GPS data and IMU data, receiving checkpoints, calculating heading, bearing and distance.


GeoController Flow Diagram


Receiving and parsing GPS data

The first task was to interface the GPS module to the SJOne board (using UART3), and receive raw data over it. The module was configured to receive only GPGGA NMEA sentence at 9600 bps baud rate. The received NMEA data is a string, that has to be parsed to obtain current latitude and longitude values. This location data is continuously sent to the Master controller on the CAN bus at 10 Hz.

Heading Calculation

Heading of the car is the direction that the car is moving, with respect to true north. A compass gives heading with respect to magnetic north. True heading is calculated by adding magnetic declination at that particular location, to the magnetic heading.

The IMU module has to be calibrated initially. The board comes programmed with the 8MHz Arduino bootloader (stk500v1) and some example firmware that demos the output of all the sensors (accelerometer, magnetometer, gyroscope). The calibration was done by following this tutorial at https://github.com/Razor-AHRS/razor-9dof-ahrs/wiki/Tutorial. Calibration compensates for the magnetic field around the IMU. So this process has to be done once after mounting the IMU on the car.

The IMU module is interfaced to the SJOne board using UART2. The IMU firmware is updated such that it gives only Yaw readings. Yaw (or magnetic heading) is used to calculate the true heading using the below formula.

Heading = Yaw data from IMU + Magnetic Declination

Magnetic declination in San Jose is +13° 29'.

Bearing calculation

Bearing is the direction that the car desires to travel along, i.e., the direction of the destination. It is calculated using the current location coordinates and the destination coordinates (or next checkpoint coordinates). The formula to calculate bearing is

   X = cos(lat2) * sin(dLong)
   Y = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLong)
   Bearing = atan2(X,Y)
   (lat1, long1) are the current location coordinates
   (lat2, long2) are the checkpoint coordinates
   dLong is (long2 - long1) 

Distance calculation

The distance between the current location and the next checkpoint is calculated using the below formula.

Haversine formula to calculate distance

  a = sin²(Δφ /2) + (cos φ1 ⋅ cos φ2 ⋅ sin²(Δλ/2))
  c = 2 x atan2( √a, √(1−a) )
  Distance d = R x c
            Φ is latitude
            λ is longitude
            R is Earth’s radius = 6371 Km
            Δφ = latitude2 – latitude1
            Δλ = longitude2 – longitude1

A flag is set when the distance to the final checkpoint becomes zero, and sent to the Master controller, to indicate that the destination has been reached.

Master Controller

Team Members:

Ajai Krishna Velayutham
Goutam Madhukeshwar Hegde

The Master Controller receives obstacle information from the Sensor Controller, navigation data from the Geo Controller and routing information from the Bluetooth Controller, collates all this information and provides driving directions to the Motor Controller.

Hardware Design

The Hardware Design is as show below with just CAN bus connection to the Master Controller. Master has the connection with all the other controllers via CAN Bus. Hardware interface explains the signalling through the CAN bus.

Master Controller Interface

Hardware Interface

The Hardware interface is simpler compared to other controllers, by just connecting to the CAN bus as shown above. The messages on the CAN such as Start and Stop command's from Bluetooth controller, Heading, Bearing and destination check signals from Geo Controller and Sensor range values from the proximity sensors are received from the CAN Bus. Based on these signals master drives the Car by sending out signals to Motor Controller, such as speed and steer values, which signifies at what sped the car has to move and at what steer the car should take.

Software Design

Master controller software consists of a state machine running 3 different states based on the sensor and geo inputs.

Master Controller Flow Diagram

Above Flow diagram represents the control flow of the master. On start of the master controller, it waits for the Start command from Bluetooth controller i.e from the App. Once the signal is given, it checks if the way points are received and stored by the Geo Controller and if the way points are sent by clicking route on the app and stored in Geo controller, then the master checks if the Geo location is not the same as destination, then Navigation algorithm is used if there are no obstacles detected by sensors, else if there are obstacles detected, then Obstacle avoidance algorithm is implemented.

Master controller software mainly deals with obstacle avoidance and GPS navigation algorithms. Software is designed with the help of state machines to make it more modular and efficient. Design of algorithms using state machines is explained in following section.

Obstacle avoidance algorithm: Obstacle avoidance is done according to the enum values sent from the sensor controller. In the master controller, obstacle avoidance is handled separately in danger,near and medium regions. If sensor indicates danger region,it means that there is an obstacle very near to front sensor. So in this case car takes a reverse turn until the front sensor enters near region.So in this way car avoids obstacle very near to it.

If sensor indicates near region,master enters a states machine to intelligently avoid the obstacle as shown the below figure.

Obstacle Avoidance State Diagram for Near Region

State machines take the three ultrasonic sensors reading from sensor controller as inputs based on which it makes the decisions to issue speed and steer command to the motor controller. To elobarate, let's see an example state transition in the above state diagram. Let's assume that currently car is moving in the forward direction.So the current state is SLOW,STRAIGHT.Now if an obstacle is detected by the left sensor,input for the state machine will be 100.So car should take right turn to avoid the obstacle.So state transition happens to the next state SLOW,RIGHT.In the similar manner, all the decisions are made in the state diagram.

If sensor indicates medium region,master enters another state machine to handle the obstacles in medium region.

Obstacle Avoidance State Diagram for Mid Region

Bit representation are the sensor values detected i.e. the leftmost bit is the value of Left sensor, followed by front sensor value as mid bit and later the right sensor value as the final bit. Value is set to 1 if an obstacle is detected and 0 if there is no obstacle, in the above diagrams for Obstacle avoidance algorithm.

Navigation Algorithm:

Steer control based on turn angle

GPS Navigation is done based on the heading and bearing values from GEO controller.Master controller calculates the desired turn angle to reach the destination path.

Turn angle= GPS bearing-GPS heading;

Turn angle is a value between 0 to 360 degree.Entire 360 degrees is divided into various sub-regions based on the desired turn angles as shown in the above figure. GPS navigation is done with the help of a state machine.Turn angle is the input for the state machine based on which state machine determines the command to issue to the motor.


Master controller software is implemented with the help of state machines.The main state machine consists of three states.

1.Obstacle avoidance state
2.GPS navigation state
3.Move reverse state

code snippet of state machine stucture:

typedef struct{
   state_t state; //state here corresponds to ST_REVERSE,ST_GPS_NAVIGATE and ST_OBSTACLE_AVOID
   state_t (*func)(void); //this is the funcction pointer declaration to switch between moveReverse,GPS_navigate and obstacleAvoid functions
} stateTrans_t;

stateTrans_t stateTrans[]=

We have created a separate state for move reverse because in order to change the motor speed to reverse, ESC of the car needs brake pulse followed by reverse.So whenever an obstacle is in danger region,we issue break first for 3 to 4 seconds followed by reverse command.So we handled this with the help of count variable in 100Hz periodic function. In the obstacle avoidance state,first we check sensor readings and based on which program calls the state machines corresponding to near region or medium region. If the sensor readings indicate that there are no near by obstacles, state transits to navigation state. In the navigation state commands to motor is issued based on the turn angle calculated based on the heading and bearing values sent by geo controller.

Following function runs in the periodic function to update the state of the car.

cState= (stateTrans[cState].func)();

Following functions are implemented in the periodic functions.

Master Controller Tasks
Task Name Purpose
Period Init Initialize CAN bus
Periodic 1Hz Callback Check can bus off
Periodic 10Hz Callback decode_START_CMD, decode_GEO_SEND_HD_BR, dbc_decode_SENSOR_SONAR, State machine to change the system states
Periodic 100Hz Callback encode_and_send_MOTOR_CONTROL

Testing & Technical Challenges

Motor & I/O Issues

  • Reverse Current from Motor: One of our boards got burnt while testing Brushless DC Motor. We would highly recommend using an Optoisolator such as ILQ74 for additional protection from reverse current etc. if you are synchronizing with the ESC for the first time.
  • ESC Synchronization: The slowest speed of Brushless DC motor was too fast for us. We tried to change ESC synchronization and reprogram it to change PWM frequency but it didn't work out for us. We recommend having Brushed DC Motor that is reprogrammable to any PWM frequency.
  • ESC Modes: ESC Board was only set to forward and reverse mode. So we were not able to control the speed to stop the motor, even after sending stop signal it would hit the obstacle. So we reprogrammed the ESC to forward, reverse and brake. Synchronizing took time and effort. ESC has various modes we can program it into.
  • Going Reverse issues: If we wanted to go reverse first without going forward, car would go full speed in reverse. So every time we got reverse command from master, we initialized the DC motor to idle and then go to reverse.
  • LCD Refresh Rate Issue: For debugging, we wanted to run LCD at 10hz but it took long time to refresh, so data didn't get printed. Hence we were forced to debug especially at 1 Hz.

Bluetooth Bridge Controller and Android application Issues


  • During the initial phase we were finding difficult to connect to the Bluetooth Module HC-06, later on proper UUID was given which solved the connection issue.
  • Sending out Start and Stop messages of "1" and "0" respectively continuously was a challenge. This was required to detect when Bluetooth goes out of range. We solved this issue using threads.
  • We had tested the application by hard coding the values from the Bluetooth controller end, which was displayed as messages on the application. The requirement was to display the CAN messages, therefore once we integrated on board, we faced issues like receiving junk and ? character on the application. We solved this by introducing circular buffers.
  • On integrating with on board GPS, we were unable to send out all the Navigation way points, say if we got 8 way points, we were able to send only first 4 of them. This was due to buffer size which we had set to 100. Once we updated it to 500, we were able to receive all the CAN messages flawlessly.


  • At Module level, we tested the communication between the Bluetooth Controller and the Android by sending out characters through UART and displaying the received messages on the app screen.
  • We increased the number of characters to 960 characters that was being sent on UART to check whether we were able to receive on the app.
  • Verified the Location of the maps on the app with the Google maps application.
  • Verified the messages displayed on the Bus Master and LCD with the app screen post integration.

Geo controller Issues

  • While initially testing IMU in raw data mode, the module was providing improper data values. We had to calibrate the Gyrometer and Magnetometer to get exact angles with precision of +/- 2 degrees. Even after this, the magnetometer's readings were changing when any soft/hard iron object was taken near the sensor. In order to remove electromagnetic interference generated from DC motor, we had to place our IMU far from DC Motor. The IMU has to be calibrated once again after mounting it on the car to avoid drift in the Yaw values.
  • The GPGGA sentence received via UART was incomplete sometimes, resulting in incorrect parsing. This turned out to be an issue with the UART receive queue size. When this queue size was increased, complete NMEA sentences were received.
  • Initially, the coordinates received from the GPS module were pointing to Santa Clara, around 30 km away from our present location. This was due to incorrect parsing of the NMEA sentence from the GPS module. The latitude and longitude values from the GPS module are given in the form of ddmm.mmmm and dddmm.mmmm and not decimal degrees. The minutes have to be converted to degrees and added to the degrees value.


In a span of 3 months, we had an awesome experience in working together for the AutoNav project. We learnt a lot about GIT and CAN bus along with implementing DBC and working on real hardware. We were able to implement all these embedded concepts effectively from our course work. All essential phases of software development cycle such as design, implementation and testing were executed in stages effectively and debugging with CAN bus was really helpful in working. Finally it was an enchanting experience and we hope that we were able to share some of our learnings and difficulties we faced in this report, which would help the future students joining the course.

Project Video

AutoNav - The autonomous RC car

GitLab Source Code



We would like to thank Preet for his guidance,consistent feedback and setting intermediate goals for the project completion on-time. We would like to thank ISA team for their support and valuable inputs at each step of the project,without which we would have not made our car work.

References Used

List of references used in the project.

[1] Preetpal Kang's lecture notes of CMPE 243, Computer Engineering, San Jose State University, Aug-Dec 2016.
[2] LPC1758 User Manual
[3] Parallax Ultrasonic Sensor
[4] Razor IMU
[5] Razor IMU Tutorial
[6] Adafruit Ultimate GPS Breakout - 66 channel w/10 Hz updates - Version 3
[7] Calculate distance between two points
[8] Programming Guide
[9] Google Maps Guide
[10] Video guide for Google maps implementation