Rebuild An Rc Car With Esp32 & Arduino Code

About the project

Rebuild an RC Car from scratch as long as the car features DC motor for the FW/BW movement and 3-wire Servo for steering wheel control

Project info

Difficulty: Moderate

Estimated time: 3 hours

License: GNU General Public License, version 3 or later (GPL3+)

Story

The present document provides all the information needed to rebuild an RC CAR from scratch using ESP32-based microcontroller units (MCUs), programmed in Arduino environment. The current project applies to the 1:16 Xinlehong (XLH)9136 model, but can be easily adapted to any RC Car model that incorporates:a) DC motor for the forward/backward (FW/BW) movement of the car,b) 3-wireServo Motor (operating at 5V) for the control of the steering wheel,c) 2S LiPo battery (of 7.4 nominal voltage or perhaps of higher voltage if taking into consideration the specifications and limitations of the boards held by the proposed system).

To complile this project with Arduino IDE you need to install:
1) ESP32 package (run Boards Manager in Arduino IDE)
2) Servo ESP32 library, available at: https://github.com/RoboticsBrno/ServoESP32
3) Adafruit_INA219, available at: https://github.com/adafruit/Adafruit_INA219
4) ThingPulse OLED SSD1306, available at: https://github.com/ThingPulse/esp8266-oled-ssd1306

Download a detailed report of the present project here

Demonstrationvideo:

Step-by-step guide to help you rebuild anRC Car (in the following 5videos)

Step1: Acquiring data from the Remote Control device

Step 2: Providing a RF link between the Remote Control device and RC Car

Step 3: Detailed description of the RC Car hardware setup

Step 4: Sending commands to the RC Car (i.e., FW/BW movement, L/R turn, Steering Wheel alignment)

Step 5: Acquiring consuming Current and Voltage of the RC Car & sending data to the Remote Contol

CAD, enclosures and custom parts

Lid.stl

3D Printer file for RC Car Enclosure's Lid

Go to download

SCAD source code file

source code for the 3D Models of the enclosure

Go to download

Enclosure.stl

3D Printer source file for RC Car Enclosure

Go to download

Code

Remote_Controller.ino

This is the code for the Remoter Control device

#include <esp_now.h> #include <WiFi.h> #include <Wire.h> #include "SSD1306Wire.h" SSD1306Wire display(0x3d, SDA, SCL); // I2C Addr = 0x3D typedef void (*Demo)(void); int demoMode = 0; uint8_t broadcastAddress[] = {0x78, 0xE3, 0x6D, 0x1B, 0x1B, 0xC8}; //D1R32 MAC Address on RC Car float Battery; int Battery_Percentage; unsigned int I_mA; int Wheels=A2, Steering=A1, ServoAdj=A0; // Define Analog Channels int ADC_Resolution = 4095; //ADC InputRange: 0-3V3; thus lsb=InputRange/2^12=0.8mV int ADC_Wheels, ADC_Steering, ADC_ServoAdj, Wheels_Mapped, Steering_Mapped, ServoAdj_Mapped; int FW_BW, L_R; const int SteeringQ=35, WheelsQ=27; // quiescent point steering & wheels const int Hysteresis = 3; // add hysteresis from quiescent point // Structure holding values to be sent by the REMOTE CONTROL typedef struct RemoteControl_Outgoing { signed char ForwardBackward; signed char LeftRight; signed char LeftRight_Adj; } RemoteControl_Outgoing; RemoteControl_Outgoing CAR; // Structure holding values to be sent by the RC CAR typedef struct CAR_Outgoing { unsigned char BatVoltage; unsigned int Current; } CAR_Outgoing; CAR_Outgoing REMOTE_CONTROL; // Create a struct_message to hold incoming readings sent by the RC CAR CAR_Outgoing incomingReadings; esp_now_peer_info_t peerInfo; // Callback when data is received void OnDataRecv(const uint8_t * mac, const uint8_t *incomingData, int len) { memcpy(&incomingReadings, incomingData, sizeof(incomingReadings)); Battery = (float) incomingReadings.BatVoltage; Battery = (Battery * 3.3/63.0) * 4.0; // ADC for battery is mapped in the RC Car system from 1-4095 to 1-31(0.1V resolution) Battery_Percentage = (int)(Battery*100.0); Battery_Percentage = map(Battery_Percentage,640,840,0,100); //Serial.println(incomingReadings.Current); //!!//Serial.println((String) "Battery=" + Battery + '\t' + "Battery_Percentage=" + Battery_Percentage + '%' + '\t' + "Current=" + incomingReadings.Current); } // Callback when data is sent void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) { } void setup() { display.init(); display.flipScreenVertically(); display.setFont(ArialMT_Plain_10); //!!//Serial.begin(115200); WiFi.mode(WIFI_STA); WiFi.disconnect(); esp_now_init(); WiFi.setTxPower(WIFI_POWER_8_5dBm); esp_now_register_send_cb(OnDataSent); // Get the status of Trasnmitted packet memcpy(peerInfo.peer_addr, broadcastAddress, 6); // Register peer peerInfo.channel = 0; peerInfo.encrypt = false; esp_now_add_peer(&peerInfo); // Add peer esp_now_register_recv_cb(OnDataRecv); // Register for a callback function that will be called when data is received } void drawProgressBarDemo() { // draw the progress bar display.drawProgressBar(0, 0/*32*/, 120, 10, Battery_Percentage); // draw the percentage as String display.setTextAlignment(TEXT_ALIGN_CENTER); display.drawString(64, 15, "BATTERY= " + String(Battery_Percentage) + "%"); } Demo demos[] = {drawProgressBarDemo}; ///Demo demos[] = {drawFontFaceDemo, drawTextFlowDemo, drawTextAlignmentDemo, drawRectDemo, drawCircleDemo, drawProgressBarDemo, drawImageDemo}; int demoLength = (sizeof(demos) / sizeof(Demo)); void loop() { if (incomingReadings.Current == 0) Battery=0; // based on a revision of ..Arduino\libraries\esp8266-oled-ssd1306-master\examples\SSD1306SimpleDemo display.clear(); // draw the current demo method demos[demoMode](); display.setFont(ArialMT_Plain_16); display.setTextAlignment(TEXT_ALIGN_RIGHT); display.drawString(128, 48, String(Battery) + "V"); // Battery Voltage display.setTextAlignment(TEXT_ALIGN_LEFT); display.drawString(1, 48, String(incomingReadings.Current) + "mA" );///display.drawString(128, 54, String(millis())); // write the buffer to the display display.display(); //Steering Wheel ADC_Steering = analogRead(Steering); Steering_Mapped = map(ADC_Steering,160,4095,1,63); //Decrease Resolution of Steering Wheels //Serial.println((String) "Steering_Mapped=" + Steering_Mapped); if (Steering_Mapped > SteeringQ+Hysteresis) L_R = Steering_Mapped - (SteeringQ+Hysteresis); // LEFT (positive value) else if (Steering_Mapped < SteeringQ-Hysteresis) L_R = (Steering_Mapped-SteeringQ+Hysteresis); //RIGHT (negative value) else L_R=0; //4WD Movement ADC_Wheels = analogRead(Wheels); Wheels_Mapped = map(ADC_Wheels,1270,4095,1,63); //Decrease Resolution of Wheels if (Wheels_Mapped > WheelsQ+Hysteresis) FW_BW = Wheels_Mapped - (WheelsQ+Hysteresis); //FORWARD (positive value) else if (Wheels_Mapped < WheelsQ-Hysteresis) FW_BW = (Wheels_Mapped-WheelsQ+Hysteresis); //BACKWARD (negative value) else FW_BW=0; //Servo adjustment (Steering Wheel alignment) ADC_ServoAdj = analogRead(ServoAdj); ServoAdj_Mapped = map(ADC_ServoAdj,0,4095,0,32); //Decrease Resolution of Servo trimming value ServoAdj_Mapped -= 16; //Serial.println((String) "Forward/Backward=" + FW_BW + '\t' + "Left/Right=" + L_R + '\t' + "Steering Alignment=" + ServoAdj_Mapped); // Prepare & Transmit data to the RC Car CAR.ForwardBackward = (signed char)FW_BW; CAR.LeftRight = (signed char)L_R; CAR.LeftRight_Adj = (signed char)(ServoAdj_Mapped); esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &CAR, sizeof(CAR)); }

RC-Car.ino

This is the code for the RC Car system

#include <Wire.h> #include <Adafruit_INA219.h> #include <esp_now.h> #include <WiFi.h> #include <Servo.h> Servo myservo; Adafruit_INA219 ina219; uint8_t broadcastAddress[] = {0x60, 0x55, 0xF9, 0x21, 0xCC, 0xD4}; //C3 MINI MAC Address on Remote Control int LiPo=A7, Voltage, Voltage_Mapped; // Read the (divided by 2) Battery voltage from Analog Pin 7 unsigned char Battery; float current_mA; unsigned int I_mA; int Receive_Timeout; // Steering Wheel initally alignment const int SERVO_QUIESCENT = 90; // 4WD Movement const int pwmMOTOR = 13; // Forward/Backward PWM pin const int dirMOTOR = 12; // Forward/Backward DIR pin const int pwmChannel_MOTOR = 2; //!!//SERVO is attached to pwm channel 2 // PWM settings const int pwmFreq = 50; const int pwmResolution = 8; // 8bits (0-255) // Servo is initially set at 90 degrees unsigned char servoValue=SERVO_QUIESCENT; // Variables to store incoming readings int FW_BW, L_R, L_R_Adj; // Variables to drive the RC Car int CAR_FW, CAR_BW, CAR_LEFT, CAR_RIGHT; // Structure holding values to be sent by the REMOTE CONTROL typedef struct RemoteControl_Outgoing { signed char ForwardBackward; signed char LeftRight; signed char LeftRight_Adj; } RemoteControl_Outgoing; RemoteControl_Outgoing CAR; // Create a struct_message to hold incoming readings sent by the REMOTE CONTROL RemoteControl_Outgoing incomingReadings; // Structure holding values to be sent by the RC CAR typedef struct CAR_Outgoing { unsigned char BatVoltage; unsigned int Current; } CAR_Outgoing; CAR_Outgoing REMOTE_CONTROL; esp_now_peer_info_t peerInfo; // Callback when data is received void OnDataRecv(const uint8_t * mac, const uint8_t *incomingData, int len) { Receive_Timeout=0; memcpy(&incomingReadings, incomingData, sizeof(incomingReadings)); FW_BW = incomingReadings.ForwardBackward; L_R = incomingReadings.LeftRight; L_R_Adj = incomingReadings.LeftRight_Adj; //!!//Serial.println ( (String) "FW_BW=" + FW_BW + '\t' + '\t' + "L_R=" + L_R + '\t' + '\t' + "L_R_Adj=" + L_R_Adj ); // Prepare PWM configuration for the RC Car (Forward: 1 to 33 , Backward: -1 to -23 , Left: 1 to 25 , Right: -1 to -31) if (FW_BW>0) CAR_FW = map(FW_BW,1,33,1,255); if (FW_BW<0) CAR_BW = map(FW_BW,-1,-23,1,255); if (FW_BW==0) CAR_BW = CAR_FW = 0; if (L_R>0) CAR_LEFT = map(L_R,1,25,1,35); //1,255); // Don't let servo to turn from 0-180 (instead from 1-255 map to 1-35); if (L_R<0) CAR_RIGHT = map(L_R,-1,-31,1,35); //1,255); // thus the SERVO will turn from 90-35 to 90+35 if (L_R==0) CAR_RIGHT = CAR_LEFT = 0; Serial.println ( (String) '\t' + "CAR_FW=" + CAR_FW + '\t' + "CAR_BW=" + CAR_BW + '\t' + "CAR_LEFT=" + CAR_LEFT + '\t' + "CAR_RIGHT=" + CAR_RIGHT ); // 4WD Movement: generate PWM signal if (CAR_FW>0 && CAR_BW==0) { digitalWrite(dirMOTOR,LOW); //Forward ledcWrite(pwmChannel_MOTOR, (CAR_FW+CAR_BW) ); } else if (CAR_BW>0 && CAR_FW==0) { digitalWrite(dirMOTOR,HIGH); //Backward ledcWrite(pwmChannel_MOTOR, (CAR_FW+CAR_BW) ); } else ledcWrite(pwmChannel_MOTOR, 0 ); // Steering Wheel: Prepare & Write Servo value if (CAR_LEFT>0 && CAR_RIGHT==0) { servoValue = (unsigned char) (SERVO_QUIESCENT-CAR_LEFT+L_R_Adj) ; } else if (CAR_RIGHT>0 && CAR_LEFT==0) { servoValue = (unsigned char) (SERVO_QUIESCENT+CAR_RIGHT+L_R_Adj); } else servoValue = (unsigned char)(SERVO_QUIESCENT+L_R_Adj); myservo.write(servoValue); // Write Servo value //!!//Serial.println (servoValue); // Prepare Voltage and Current Measurements Voltage = analogRead(LiPo); Voltage_Mapped = map(Voltage,1,4095,1,63); Battery = (unsigned char)Voltage_Mapped; //read Current float current_mA = ina219.getCurrent_mA(); I_mA = (unsigned int)current_mA; // Transmit Voltage and Current data to the Remote Control device REMOTE_CONTROL.BatVoltage = Battery; REMOTE_CONTROL.Current = I_mA; esp_err_t result = esp_now_send(broadcastAddress, (uint8_t *) &REMOTE_CONTROL, sizeof(REMOTE_CONTROL)); } // Callback when data is sent void OnDataSent(const uint8_t *mac_addr, esp_now_send_status_t status) { } void setup() { ina219.begin(); // 4WD Movement pinMode(dirMOTOR, OUTPUT); // Forward/Backward DIR pin ledcSetup(pwmChannel_MOTOR, pwmFreq, pwmResolution); // configure PWM ledcAttachPin(pwmMOTOR, pwmChannel_MOTOR); // attach PWM channel to the GPIO pin to be controlled // Steering Wheel myservo.attach(27); // attach Servo pin Serial.begin(115200); WiFi.mode(WIFI_STA); WiFi.disconnect(); esp_now_init(); WiFi.setTxPower(WIFI_POWER_8_5dBm); memcpy(peerInfo.peer_addr, broadcastAddress, 6); // Register peer peerInfo.channel = 0; peerInfo.encrypt = false; esp_now_add_peer(&peerInfo); // Add peer // Register for a callback function that will be called when data is received esp_now_register_recv_cb(OnDataRecv); } void loop() { Receive_Timeout++; if (Receive_Timeout > 200000) { ledcWrite(pwmChannel_MOTOR, 0 ); Receive_Timeout=200000; // stall counter (@ value higher than 200000) until RF communication is restored (about 2sec delay) } }

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Rebuild An Rc Car With Esp32 & Arduino Code

About the project

Project info

Story

CAD, enclosures and custom parts

Lid.stl

SCAD source code file

Enclosure.stl

Code

Remote_Controller.ino

RC-Car.ino

Credits

dbolanakis

Leave your feedback...

Shop

Project Hub

Video

Blog

Shop home

3D printing

Single Board Computers

Development kits

Sensors

Internet of things

Robotics

Accessories

Product of the Week

Electromaker Educator

The Electromaker Show

The Electromaker Podcast

Rebuild An Rc Car With Esp32 & Arduino Code

About the project

Project info

Story

CAD, enclosures and custom parts

Lid.stl

SCAD source code file

Enclosure.stl

Code

Remote_Controller.ino

RC-Car.ino

Credits

dbolanakis

Leave your feedback...

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