小车概述

参考链接： Arduino Obstacle Avoiding Robot Car 2WD With AA Battery YFROBOT Motor Driver Library for Arduino 可用模块： L298P / PM-R3 / MD01 / MD02 / MD03 / MD04 / MD_GB36 / IIC_MOTORDRIVER / IIC_MOTORDRIVER_RZ7889 小车套件： VALON / 4WD Mecanum Wheel

由 ESP32 驱动的 FPV 汽车

https://www.youtube.com/watch?v=E2raPpB2aJ0

Arduino智能小车 https://www.hackster.io/goldscrew/arduino-obstacle-avoiding-robot-car-2wd-with-aa-battery-514b3c https://www.codemahal.com/2wd-robotic-car-arduino https://www.instructables.com/OSOYOO-2WD-Robot-Car-Starter-Kit/

树莓派 智能小车 化繁为简！开发者尝鲜阿里小程序云平台，实操讲解如何打造智能小车！

Remote Control

https://www.youtube.com/watch?v=SVlm7QU5Nkk https://www.seeedstudio.com/blog/2023/04/13/ble-wifi-remote-using-seeed-studio-xiao-esp32c3/

https://www.e-tinkers.com/2019/11/build-an-esp32-web-server-and-ir-remote/

https://oshwhub.com/satun/c3mini-yao-kong-qi_copy https://www.youtube.com/watch?v=SVlm7QU5Nkk https://www.hackster.io/techstudycell/esp32-bluetooth-home-automation-with-ir-remote-control-relay-10d4e8?f=1 https://www.youtube.com/watch?v=dODmsoAu0D4

基本控制器

Remote Control Options for an ESP32-C3 Smart Car

Method Technology Range Latency Power Consumption Ease of Implementation Pros Cons
Wi-Fi Web Server Wi-Fi (ESP32-C3 as AP/STA) Up to 100m Medium (~50ms) High ⭐⭐⭐⭐ - Control via any browser. - No app required. - Requires Wi-Fi network. - Higher power usage.
Wi-Fi WebSocket Wi-Fi (Real-time) Up to 100m Low (~10ms) High ⭐⭐⭐⭐ - Faster than HTTP. - Works on a local network. - Requires a stable connection.
Wi-Fi MQTT Wi-Fi + MQTT Broker Internet-wide Medium (~100ms) Medium ⭐⭐⭐ - Remote control from anywhere. - Supports cloud integration. - Needs an MQTT broker. - Slight delay.
Bluetooth Classic Bluetooth BR/EDR ~10m Low (~10ms) Low ⭐⭐⭐ - Works with classic Bluetooth controllers. - ESP32-C3 lacks Bluetooth Classic.
Bluetooth LE (BLE) Bluetooth Low Energy ~10m Low (~20ms) Very Low ⭐⭐⭐⭐ - Energy-efficient. - Works with smartphones. - Less bandwidth than Wi-Fi. - Limited range.
ESP-NOW Proprietary ESP32 Protocol ~50m (LOS) Very Low (~5ms) Very Low ⭐⭐⭐⭐⭐ - No Wi-Fi required. - Very low latency. - Limited to ESP-based devices.
LoRa Long Range Radio (433MHz - 915MHz) Up to 10km High (~500ms+) Very Low ⭐ - Very long-range. - Very slow data rate. - Needs extra LoRa module.
NRF24L01 2.4GHz RF Module Up to 1km Low (~10ms) Low ⭐⭐ - Simple, fast, and reliable. - Requires additional module. - Not internet-capable.
IR Remote Infrared (38kHz) Up to 5m Low (~10ms) Very Low ⭐⭐⭐ - Cheap and simple. - Needs line-of-sight. - Can be affected by sunlight.
RF Remote (433MHz/315MHz) Radio Frequency (RF) Up to 100m Low (~20ms) Low ⭐⭐ - Cheap modules available. - No pairing needed. - No encryption. - Prone to interference.
ZigBee ZigBee（IEEE 802.15.4） 100m low low - 低功耗，支持多设备组网 通信距离较短（通常100米以内）
4g/5g LTE 基站 不限距离 low low 不限距离 全球可用 流量费用贵  

Wi-Fi WebSocket

WebSocket provides real-time, low-latency communication between a Web UI or another ESP32 device and your ESP32-C3 smart car over Wi-Fi.

(A) WebSocket Server (Receiver - ESP32-C3 on Smart Car) This ESP32-C3 will receive commands from a WebSocket client (e.g., a web browser or another ESP32).

#include <WiFi.h>
#include <WebSocketsServer.h>
const char* ssid = "YOUR_SSID";
const char* password = "YOUR_PASSWORD";

WebSocketsServer webSocket(81);

void handleWebSocketMessage(uint8_t *payload) {
    Serial.printf("Received: %s\n", payload);
    if (strcmp((char*)payload, "FORWARD") == 0) {
        // Move car forward
    } else if (strcmp((char*)payload, "STOP") == 0) {
        // Stop the car
    }
}

void webSocketEvent(uint8_t num, WStype_t type, uint8_t *payload, size_t length) {
    if (type == WStype_TEXT) {
        handleWebSocketMessage(payload);
    }
}

void setup() {
    Serial.begin(115200);
    WiFi.begin(ssid, password);
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
    }
    Serial.println("Connected!");

    webSocket.begin();
    webSocket.onEvent(webSocketEvent);
}

void loop() {
    webSocket.loop();
}

(B) WebSocket Client (Sender - Web Browser) Use this simple HTML/JavaScript webpage to control the ESP32 smart car from a browser.

<!DOCTYPE html>
<html>
<head>
    <title>ESP32 Car Controller</title>
</head>
<body>
    <button onclick="sendCommand('FORWARD')">Move Forward</button>
    <button onclick="sendCommand('STOP')">Stop</button>
    
    <script>
        const socket = new WebSocket("ws://ESP32_IP:81");

        socket.onopen = () => console.log("Connected to ESP32");
        socket.onmessage = (event) => console.log("Received:", event.data);

        function sendCommand(cmd) {
            socket.send(cmd);
        }
    </script>
</body>
</html>

ESP-NOW (ESP32-to-ESP32 Communication)

ESP-NOW is fast (low latency ~5ms), lightweight, and doesn’t require Wi-Fi.

(A) ESP-NOW Receiver (ESP32-C3 on Smart Car)

#include <esp_now.h>
#include <WiFi.h>

typedef struct {
    char message[32];
} CarCommand;

void OnDataRecv(const uint8_t * mac, const uint8_t *incomingData, int len) {
    CarCommand command;
    memcpy(&command, incomingData, sizeof(command));
    Serial.printf("Received: %s\n", command.message);
}

void setup() {
    Serial.begin(115200);
    WiFi.mode(WIFI_STA);
    if (esp_now_init() != ESP_OK) {
        Serial.println("ESP-NOW Init Failed");
        return;
    }
    esp_now_register_recv_cb(OnDataRecv);
}

void loop() {
}

(B) ESP-NOW Sender (ESP32 Remote)

#include <esp_now.h>
#include <WiFi.h>

typedef struct {
    char message[32];
} CarCommand;

CarCommand command;
esp_now_peer_info_t peerInfo;
uint8_t receiverMAC[] = {0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX}; // Replace with receiver ESP32 MAC

void sendCommand(const char* cmd) {
    strcpy(command.message, cmd);
    esp_now_send(receiverMAC, (uint8_t*)&command, sizeof(command));
}

void setup() {
    Serial.begin(115200);
    WiFi.mode(WIFI_STA);

    if (esp_now_init() != ESP_OK) {
        Serial.println("ESP-NOW Init Failed");
        return;
    }

    memcpy(peerInfo.peer_addr, receiverMAC, 6);
    peerInfo.channel = 0;
    peerInfo.encrypt = false;
    esp_now_add_peer(&peerInfo);
}

void loop() {
    sendCommand("FORWARD");
    delay(2000);
    sendCommand("STOP");
    delay(2000);
}

Note: Replace receiverMAC with the receiver ESP32’s MAC Address (use WiFi.macAddress() to get it).

NRF24L01 (2.4GHz RF Communication)

NRF24L01 allows ESP32-to-ESP32 communication without Wi-Fi, using radio signals.

Hardware Setup Connect the NRF24L01 module to ESP32 via SPI: MISO → GPIO 19 MOSI → GPIO 23 SCK → GPIO 18 CSN → GPIO 5 CE → GPIO 4

(A) NRF24L01 Receiver (ESP32-C3 on Smart Car)

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

RF24 radio(4, 5); // CE, CSN pins
const byte address[] = "00001";
char receivedCommand[32];

void setup() {
    Serial.begin(115200);
    radio.begin();
    radio.openReadingPipe(0, address);
    radio.setPALevel(RF24_PA_MIN);
    radio.startListening();
}

void loop() {
    if (radio.available()) {
        radio.read(&receivedCommand, sizeof(receivedCommand));
        Serial.printf("Received: %s\n", receivedCommand);
        // Handle command
    }
}

(B) NRF24L01 Sender (ESP32 Remote)

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

RF24 radio(4, 5); // CE, CSN pins
const byte address[] = "00001";

void setup() {
    Serial.begin(115200);
    radio.begin();
    radio.openWritingPipe(address);
    radio.setPALevel(RF24_PA_MIN);
    radio.stopListening();
}

void loop() {
    char text[] = "FORWARD";
    radio.write(&text, sizeof(text));
    Serial.println("Sent FORWARD");
    delay(2000);

    char stopText[] = "STOP";
    radio.write(&stopText, sizeof(stopText));
    Serial.println("Sent STOP");
    delay(2000);
}

LORA

4G/5G

  1. 通信协议
通信协议 描述 特点 适用场景
4G Cat.1 中等速率通信协议，适合物联网设备 - 下行速率约10Mbps
- 低功耗
- 成本较低		 智能表计、共享设备、物流追踪
4G Cat.4 高速率通信协议，适合中高带宽需求 - 下行速率约150Mbps
- 支持语音和定位功能		 远程监控、智能交通、工业物联网
5G 超高速率通信协议，支持低延迟和高带宽 - 下行速率可达Gbps级别
- 超低延迟		 自动驾驶、远程医疗、工业自动化
NB-IoT 窄带物联网协议，适合低功耗、低速率场景 - 超低功耗
- 覆盖范围广
- 成本低		 智能表计、环境监测、农业物联网
  1. 4G/5G通信模块
模块名称 描述 特点 适用场景 与其他模块的区别
ML307R 中移物联推出的4G Cat.1通信模块 - 支持4G LTE Cat.1
- 低功耗
- 内置GNSS定位		 智能表计、共享设备、物流追踪 速率较低，适合低成本场景；SIM7600和EC20速率更高，功能更强大
SIM7600 SIMCom推出的4G LTE Cat.4模块 - 支持4G LTE Cat.4
- 内置GNSS
- 支持语音通话		 远程监控、智能交通、工业物联网 速率较高，功能丰富；ML307R速率较低，适合低成本场景
Quectel EC20 Quectel推出的4G LTE Cat.4模块 - 支持全球频段
- 下行速率150Mbps
- 内置GNSS		 远程监控、智能交通、工业物联网 速率较高，适合全球化应用；ML307R速率较低，适合低成本场景
Quectel RM500Q Quectel推出的5G模块 - 支持5G超高速率和低延迟
- 适合高带宽应用		 自动驾驶、远程医疗、工业自动化 速率和性能远超4G模块（如ML307R、SIM7600、EC20），但成本较高
  1. 固件
固件类型 描述 特点 适用场景
AT固件 基于AT指令的通信模块固件 - 简单易用
- 支持多种通信模块（如ML307R、SIM7600、Quectel模块）		 嵌入式开发、模块控制
QuecOpen Quectel提供的开发平台固件 - 提供高级API和功能
- 支持二次开发		 工业物联网、车联网、远程监控
自定义固件 用户根据需求开发的固件 - 高度定制化
- 适合特定应用场景		 特殊需求项目、科研开发

遥控器现成开源产品

Transmitter with Joysticks

ESP32 + ESP-NOW Joystick Controller Tutorial

https://www.instructables.com/ESP-NOW-Remote-Control/

ESP32 + nrf24l01 joystick

https://github.com/walcht/nRF-transmitter https://forum.dronebotworkshop.com/2018/the-nrf24l01-wireless-joystick-for-arduino-robot-car-with-nrf24l01/ https://www.youtube.com/watch?v=lhGXAJj8rJw

Image/Video Transmission 图传

Option Resolution Latency Range Difficulty Level Use Case
ESP32-CAM (Wi-Fi Streaming) Up to 1600x1200 Medium Short (~30m) Medium Live video to mobile/web browser
ESP32-CAM (ESP-NOW + Wi-Fi Hybrid) Up to 1600x1200 Medium Medium (~100m) Hard Streaming with low-latency control
ESP32-CAM + NRF24L01 Up to 800x600 Medium-High Long (~1km) Hard Video + control over radio
Analog FPV (Dedicated FPV Camera + 5.8GHz Transmitter) 480p-720p Very Low Very Long (~5km) Medium FPV drone/car setup
ESP32 with LoRa (for images, not real-time video) Low 800x600 High Very Long (~10km) Hard Slow image transfer over long distances
ESP32-S3 + OV5640 (Higher Resolution Camera) 2592x1944 Medium Short (~30m)    
ESP32 with USB Camera (UVC) 1080p Medium Short (~50m)    
ESP32 + RTSP Streaming (ESP32-CAM or S3) 1080p Medium Medium(~100m)    
5.8GHz FPV Camera (Dedicated FPV System) 720p-1080p Very Low Very Long (~5km)    
ESP32 + LTE Module (4G Streaming) 1080p Medium-High Unlimited (cellular)    
Raspberry Pi + CSI Camera ESP32 Sends Control Commands via UART or I2C to Raspberry Pi 4K Low Long (~300m with Wi-Fi)    

ESP32-S3 + OV5640 (Higher Resolution Camera)

enable 360-degree camera rotation

Method Description Pros Cons
1. Servo-Based Pan-Tilt Mechanism Uses two servo motors (one for pan, one for tilt) to move the camera. ✅ Simple to implement ✅ Works with all cameras ❌ Limited movement speed ❌ Servo jitter
2. Stepper Motor 360° Rotation Base Uses a stepper motor to rotate the entire camera module. ✅ Precise 360° rotation ✅ Stable movement ❌ More complex than servos ❌ Requires driver circuit
3. DC Motor with Slip Ring (Continuous Rotation) Uses a DC motor + slip ring to allow continuous, unrestricted 360° rotation. ✅ Infinite rotation ✅ Smooth movement ❌ Harder to control positioning ❌ Requires motor driver
4. ESP32-CAM with a Rotating Mirror (Periscope Style) Uses a small rotating mirror in front of the fixed camera lens to redirect the view. ✅ No need to move camera ✅ Works with fixed ESP32-CAM ❌ Optical distortion possible ❌ Complex mirror system

控制器+图传

Recommended Libraries and Frameworks to Search on GitHub

Option 1 Mobile App for Remote Control

WebSocket Control + Video Streaming

Search on GitHub: You can search for active repositories on GitHub by searching these terms: “ESP32-CAM WebSocket control” “ESP32 robot WiFi camera” “ESP32-CAM live video feed control”

Option 2 ESP32 and Joystick/Controller with Display

TFT Display OLED Display

Search on GitHub: Similarly, you can search for “ESP32 Joystick TFT control” or “ESP32 robot joystick with display” to find available joystick-controlled robot projects.

Option 3 ESP32 and Joystick/Controller + Mobile app for Image/Video transmission

就是前两者的配合，典型的就是遥控器配上手机

实战

2wd esp8266小车 + esp32 遥控 (espnow)

小车接线和代码

清单：

接线


电源    --------------  L298N电机驱动
正极 -------------------------  12V
负极 -------------------------  GND

ESP8266  --------------  超声波 HC-SR04 
3.3V    -------------------------   VCC
GND -------------------------   GND
D4  -------------------------   Trigger Pin
D0  -------------------------   Echo Pin

ESP8266  --------------  L298N电机驱动
VIN -------------------------   5V (电机给ESP供电)
GND -------------------------   GND
D6  -------------------------   ENA 
D8  -------------------------   IN1	(motorPinA1)
D7  -------------------------   IN2	(motorPinA2)
D2  -------------------------   IN3 (motorPinB2)
D1  -------------------------   IN4 (motorPinB1)
D5  -------------------------   ENB
 

电机 -------------- L298N电机驱动
电机的两级输入线头朝内，然后上面的线接电机驱动的最前面，下面的线接电机驱动的后面第二个

左边电机接电机驱动A侧，右边电机接电机驱动B侧。
前进时如果哪边电机有反转的情况，将该电机的两电线反接即可。

代码


#include <ESP8266WiFi.h>
#include <espnow.h>

volatile int enableAvoidCollision;
volatile int joystickYMedian;
volatile int joystickXMedian;
volatile int joystickY;
volatile int joystickX;
volatile int rotationSensorSpeed;
volatile int rotationSensorSpeedAdj;
volatile int connectionLostCountdown;
volatile int motorASpeed;
volatile int motorBSpeed;
volatile int motorASpeedAdj;
volatile int motorBSpeedAdj;

unsigned long lastTrigger = 0;
#define timeSeconds 10

const int trigPin = D4;
const int echoPin = D0;

//define sound speed in cm/uS
#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701

long duration;
float distanceCm;

// Motor A
int motorPinA1 = D8; 
int motorPinA2 = D7; 
int enablePinA = D6; 

// Motor B
int motorPinB1 = D1; 
int motorPinB2 = D2; 
int enablePinB = D5;

uint8_t motorPinA1Val;
uint8_t motorPinA2Val;
int enablePinAVal;
uint8_t motorPinB1Val;
uint8_t motorPinB2Val;
int enablePinBVal;

void OnDataRecv(uint8_t * mac, uint8_t *incomingData, uint8_t len) {
  //Serial.printf("Recived Message from MAC:%02X:%02X:%02X:%02X:%02X:%02X\n", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
  String message = "";
  for (int i = 0; i < static_cast<int>(len); i++) {
    message += String(static_cast<char>(incomingData[i]));
  }
  enableAvoidCollision = String(String(message).substring(0,1)).toInt();
  joystickY = String(String(message).substring(1,String(message).indexOf(String("Y")))).toInt();
  joystickX = String(String(message).substring((String(message).indexOf(String("Y")) + 1),String(message).indexOf(String("X")))).toInt();
  rotationSensorSpeed = String(String(message).substring((String(message).indexOf(String("X")) + 1),String(message).indexOf(String("A")))).toInt();
  rotationSensorSpeedAdj = String(String(message).substring((String(message).indexOf(String("A")) + 1),String(message).indexOf(String("B")))).toInt();
  //046Y45X90A44B
  // sscanf((char*)incomingData, "%1d%2dY%2dX%2dA%2dB", 
  //      &enableAvoidCollision, &joystickY, &joystickX, 
  //      &rotationSensorSpeed, &rotationSensorSpeedAdj);
    
  connectionLostCountdown = 10;
  lastTrigger = millis();
  RemoteControlMotorsLogic();
}

void ConnectionLostCountdownTimer() {
  if (millis() - lastTrigger >= (timeSeconds*1000)) { 
    if (connectionLostCountdown > 0) {
      connectionLostCountdown = connectionLostCountdown - 1;

    }
    if (connectionLostCountdown == 0) {
      motorASpeed = 0;
      motorBSpeed = 0;
      enableAvoidCollision = 0;
      // Serial.println("Motion stopped...");
    }
  }
}
// 0-37 move forward(0 fast, 37 slow)
// 38-48 STOP (median-4, median+4)
// 48-99 move backward (99 fast, 48 slow)
void RemoteControlMotorsLogic() {
  if (joystickY < joystickYMedian - 4) {
    if (joystickX > joystickXMedian + 4) {
      motorASpeed = (map(joystickY, 37, 0, 0, 255)) + (map(joystickX, 49, 99, 0, 255));
      motorBSpeed = (map(joystickY, 37, 0, 0, 255)) - (map(joystickX, 49, 99, 0, 255));

    }
    if (joystickX >= joystickXMedian - 4 && joystickX <= joystickXMedian + 4) {
      motorBSpeed = (map(joystickY, 37, 0, 0, 255));
      motorASpeed = (map(joystickY, 37, 0, 0, 255));

    }
    if (joystickX < joystickXMedian - 4) {
      motorASpeed = (map(joystickY, 37, 0, 0, 255)) + (map(joystickX, 37, 0, 0, (-256)));
      motorBSpeed = (map(joystickY, 37, 0, 0, 255)) - (map(joystickX, 37, 0, 0, (-256)));

    }

  }
  if (joystickY >= joystickYMedian - 4 && joystickY <= joystickYMedian + 4) {
    if (joystickX > joystickXMedian + 4) {
      motorASpeed = (map(joystickX, 49, 99, 0, 255));
      motorBSpeed = (map(joystickX, 49, 99, 0, (-256)));

    }
    if (joystickX >= joystickXMedian - 4 && joystickX <= joystickXMedian + 4) {
      motorASpeed = 0;
      motorBSpeed = 0;

    }
    if (joystickX < joystickXMedian - 4) {
      motorASpeed = (map(joystickX, 37, 0, 0, (-256)));
      motorBSpeed = (map(joystickX, 37, 0, 0, 255));

    }

  }
  if (joystickY > joystickYMedian + 4) {
    if (joystickX > joystickXMedian + 4) {
      motorASpeed = (map(joystickY, 49, 99, 0, (-256))) - (map(joystickX, 49, 99, 0, 255));
      motorBSpeed = (map(joystickY, 49, 99, 0, (-256))) + (map(joystickX, 49, 99, 0, 255));

    }
    if (joystickX >= joystickXMedian - 4 && joystickX <= joystickXMedian + 4) {
      motorBSpeed = (map(joystickY, 49, 99, 0, (-256)));
      motorASpeed = (map(joystickY, 49, 99, 0, (-256)));

    }
    if (joystickX < joystickXMedian - 4) {
      motorASpeed = (map(joystickY, 49, 99, 0, (-256))) - (map(joystickX, 37, 0, 0, (-256)));
      motorBSpeed = (map(joystickY, 49, 99, 0, (-256))) + (map(joystickX, 37, 0, 0, (-256)));

    }

  }
}

void AvoidCollision() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  // Calculate the distance
  distanceCm = duration * SOUND_SPEED/2;
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);
  if (distanceCm <= 40) {
    motorPinA1Val=HIGH;
    motorPinA2Val=LOW;
    enablePinAVal=map(constrain(180, 0, 255), 0, 255, 0, 1023);
    motorPinB1Val=LOW;
    motorPinB2Val=HIGH;
    enablePinBVal=map(constrain(180, 0, 255), 0, 255, 0, 1023);
  }else {
    motorPinA1Val=HIGH;
    motorPinA2Val=LOW;
    enablePinAVal=map(constrain(200, 0, 255), 0, 255, 0, 1023);
    motorPinB1Val=HIGH;
    motorPinB2Val=LOW;
    enablePinBVal=map(constrain(200, 0, 255), 0, 255, 0, 1023);
  }
  Serial.print("enablePinAVal:");
  Serial.println(enablePinAVal);
  Serial.print("enablePinBVal:");
  Serial.println(enablePinBVal);
  digitalWrite(motorPinA1, motorPinA1Val);
  digitalWrite(motorPinA2, motorPinA2Val);
  analogWrite(enablePinA, enablePinAVal);
  
  digitalWrite(motorPinB1, motorPinB1Val);
  digitalWrite(motorPinB2, motorPinB2Val);
  analogWrite(enablePinB, enablePinBVal);
}

void SetMotorDirectionSpeed(){
  if (rotationSensorSpeedAdj < 40) {
    motorASpeedAdj = (map(rotationSensorSpeedAdj, 0, 39, 120, 3));
    motorBSpeedAdj = (map(rotationSensorSpeedAdj, 0, 39, (-120), (-3)));
  } else {
    if (rotationSensorSpeedAdj > 59) {
      motorASpeedAdj = (map(rotationSensorSpeedAdj, 60, 99, (-3), (-120)));
      motorBSpeedAdj = (map(rotationSensorSpeedAdj, 60, 99, 3, 120));
    } else {
      motorASpeedAdj = 0;
      motorBSpeedAdj = 0;
    }
  }
  // Gear0
  if (rotationSensorSpeed < 33) {
    motorPinA1Val=LOW;
    motorPinA2Val=LOW;
    enablePinAVal=0;
    motorPinB1Val=LOW;
    motorPinB2Val=LOW;
    enablePinBVal=0;
  }
  // Gear1
  if (rotationSensorSpeed >= 33 && rotationSensorSpeed < 66) {
    
    if (motorBSpeed > 0) {
      motorPinA1Val=HIGH;
      motorPinA2Val=LOW;
      enablePinAVal=map(constrain(motorBSpeed + motorBSpeedAdj, 0, 255), 0, 255, 0, 1023);
    } else if (motorBSpeed < 0) {
      motorPinA1Val=LOW;
      motorPinA2Val=HIGH;
      enablePinAVal=map(constrain(abs(motorBSpeed - motorBSpeedAdj), 0, 255), 0, 255, 0, 1023);
    } else {
      motorPinA1Val=LOW;
      motorPinA2Val=LOW;
      enablePinAVal=0;
    }
    
    if (motorASpeed > 0) {
      motorPinB1Val=HIGH;
      motorPinB2Val=LOW;
      enablePinBVal=map(constrain(motorASpeed + motorASpeedAdj, 0, 255), 0, 255, 0, 1023);
    } else if (motorASpeed < 0) {
      motorPinB1Val=LOW;
      motorPinB2Val=HIGH;
      enablePinBVal=map(constrain(abs(motorASpeed - motorASpeedAdj), 0, 255), 0, 255, 0, 1023);
    } else {
      motorPinB1Val=LOW;
      motorPinB2Val=LOW;
      enablePinBVal=0;
    }
  }
  // Gear2
  if (rotationSensorSpeed >= 66) {
    
    if (motorBSpeed > 0) {
      motorPinA1Val=HIGH;
      motorPinA2Val=LOW;
      enablePinAVal=map(constrain(motorBSpeed + motorBSpeedAdj, 0, 255), 0, 255, 0, 1023);

    } else if (motorBSpeed < 0) {
      motorPinA1Val=LOW;
      motorPinA2Val=HIGH;
      enablePinAVal=map(constrain(abs(motorBSpeed - motorBSpeedAdj), 0, 255), 0, 100, 0, 1023);

    } else {
      motorPinA1Val=LOW;
      motorPinA2Val=LOW;
      enablePinAVal=0;
    }

    if (motorASpeed > 0) {
      motorPinB1Val=HIGH;
      motorPinB2Val=LOW;
      enablePinBVal=map(constrain(motorASpeed + motorASpeedAdj, 0, 255), 0, 255, 0, 1023);
    } else if (motorASpeed < 0) {
      motorPinB1Val=LOW;
      motorPinB2Val=HIGH;
      enablePinBVal=map(constrain(abs(motorASpeed - motorASpeedAdj), 0, 255), 0, 100, 0, 1023);
    } else {
      motorPinB1Val=LOW;
      motorPinB2Val=LOW;
      enablePinBVal=0;
    }
  }

  // Serial.print("enablePinAVal:");
  // Serial.println(enablePinAVal);
  // Serial.print("enablePinBVal:");
  // Serial.println(enablePinBVal);
  digitalWrite(motorPinA1, motorPinA1Val);
  digitalWrite(motorPinA2, motorPinA2Val);
  analogWrite(enablePinA, enablePinAVal);

  digitalWrite(motorPinB1, motorPinB1Val);
  digitalWrite(motorPinB2, motorPinB2Val);
  analogWrite(enablePinB, enablePinBVal);
}
void setup(){
  Serial.begin(115200);
  enableAvoidCollision = 0;
  joystickYMedian = 43;
  joystickXMedian = 43;
  joystickY = 43;
  joystickX = 43;
  rotationSensorSpeed = 0;
  rotationSensorSpeedAdj = 0;
  connectionLostCountdown = 0;
  motorASpeed = 0;
  motorBSpeed = 0;
  motorASpeedAdj = 0;
  motorBSpeedAdj = 0;

  Serial.println("Starting setup...");                                                                                                                                                                                                                                                                                                                          
  delay(10000);
  Serial.println("Setup complete.");

  // Set device as a Wi-Fi Station
  WiFi.mode(WIFI_STA);

  //WiFi.persistent(false);
  //WiFi.mode(WIFI_AP);
  //WiFi.disconnect();
  //WiFi.softAP("ESPNOW", nullptr, 3);
  //WiFi.softAPdisconnect(false);

  Serial.print("Device MAC:");
  Serial.println(WiFi.softAPmacAddress());

  // Init ESP-NOW
  if (esp_now_init() != 0) {
    Serial.println("Error initializing ESP-NOW");
    ESP.restart();
    //return;
  }

  // Once ESPNow is successfully Init, we will register for recv CB to
  // get recv packer info
  esp_now_set_self_role(ESP_NOW_ROLE_SLAVE);
  esp_now_register_recv_cb(OnDataRecv);

  pinMode(motorPinA1, OUTPUT);
  pinMode(motorPinA2, OUTPUT);
  pinMode(enablePinA, OUTPUT);
  pinMode(motorPinB1, OUTPUT);
  pinMode(motorPinB2, OUTPUT);
  pinMode(enablePinB, OUTPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Set PWM frequency to 25 kHz (above the audible range)
  analogWriteFreq(25000);
  // Optionally set PWM resolution; default range is 1023 on ESP8266 (10-bit resolution)
  analogWriteRange(1023);

}

void loop(){
  ConnectionLostCountdownTimer();
  if (enableAvoidCollision) {
    AvoidCollision();
  } else {
    SetMotorDirectionSpeed();
  }
}

遥控接线和代码

接线

ESP32  -----------------  OLED屏
22  --------------------  SCL（SCK）
21  --------------------  SDA
3V  --------------------- VCC
GND  ------------------- GND

ESP32  -----------------  摇杆模块
34  ---------------------  Y轴
35 ----------------------  X轴
26 ----------------------- VCC

ESP32  -----------------  电位器模块（上）
32  --------------------  信号（OUT）
27 ---------------------   VCC

ESP32  -----------------  电位器模块（下）
33  --------------------  信号（OUT）
14  ---------------------   VCC

ESP32  -----------------  按钮模块
25  --------------------  信号（S）
12  ---------------------   GND

稳压电源模块  ----------------- 各模块
5V  ---------------------   ESP32的Vin
GND  -------------------   ESP32的GND
GND  -------------------   摇杆模块的GND
GND  -------------------   电位器模块（上）的GND
GND  -------------------   电位器模块（下）的GND
GND  -------------------   按钮模块的VCC

代码(mixly 代码，待翻译成esp32版本)


#include <U8g2lib.h>
#include <Wire.h>
#include <WiFi.h>
#include <WifiEspNow.h>
#include <SimpleTimer.h>

U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, U8X8_PIN_NONE);
volatile int Y轴;
volatile int X轴;
volatile int 上旋钮;
volatile int 下旋钮;
volatile int 按钮;
String 数据;
String 挡位;
volatile int 功率修正值;
String 修正方向;
uint8_t PEER_5CCF7F0A77FB[] = {0x5C, 0xCF, 0x7F, 0x0A, 0x77, 0xFB};

SimpleTimer timer;

void page1() {
  u8g2.setFont(u8g2_font_timR10_tf);
  u8g2.setFontPosTop();
  u8g2.setCursor(0,0);
  u8g2.print(数据);
  u8g2.setFont(u8g2_font_timB24_tf);
  u8g2.setFontPosTop();
  u8g2.setCursor(15,30);
  u8g2.print(挡位);
  u8g2.setCursor(60,30);
  u8g2.print(修正方向);
  u8g2.setCursor(80,30);
  u8g2.print(功率修正值);
}

bool sendMessage(uint8_t *macAddress, String _data) {
  bool ok = WifiEspNow.addPeer(macAddress, 0, nullptr, WIFI_IF_STA);
  if (!ok) return false;
  uint16_t length = _data.length();
  char _msg[length];
  strcpy(_msg, _data.c_str());
  return WifiEspNow.send(macAddress, reinterpret_cast<const uint8_t*>(_msg), length);
}

void Simple_timer_1() {
  if (digitalRead(25)) {
    挡位 = "A";

  } else {
    if (上旋钮 < 33) {
      挡位 = "0";

    } else {
      if (上旋钮 >= 33 && 上旋钮 < 66) {
        挡位 = "1";

      } else {
        挡位 = "2";

      }

    }

  }
  if (下旋钮 < 40) {
    修正方向 = "A";
    功率修正值 = (map(下旋钮, 0, 39, 40, 1));

  } else {
    if (下旋钮 > 59) {
      修正方向 = 'B';
      功率修正值 = (map(下旋钮, 60, 99, 1, 40));

    } else {
      修正方向 = "0";
      功率修正值 = 0;

    }

  }
  u8g2.firstPage();
  do
  {
    page1();
  }while(u8g2.nextPage());
}

void setup(){
  u8g2.setI2CAddress(0x3C*2);
  u8g2.begin();
  pinMode(26, OUTPUT);
  pinMode(27, OUTPUT);
  pinMode(14, OUTPUT);
  pinMode(12, OUTPUT);
  Y轴 = 0;
  X轴 = 0;
  上旋钮 = 0;
  下旋钮 = 0;
  按钮 = 0;
  数据 = "";
  挡位 = "";
  功率修正值 = 0;
  修正方向 = "";
  digitalWrite(26,HIGH);
  digitalWrite(27,HIGH);
  digitalWrite(14,HIGH);
  digitalWrite(12,HIGH);
  u8g2.enableUTF8Print();

  pinMode(25, INPUT);

  WiFi.mode(WIFI_STA);

  Serial.print("当前设备MAC:");
  Serial.println(WiFi.macAddress());

  bool ok = WifiEspNow.begin();
  if (!ok) {
    Serial.println("WifiEspNow初始化失败");
    ESP.restart();
  }
  timer.setInterval(100L, Simple_timer_1);

}

void loop(){
  Y轴 = (map(analogRead(34), 0, 4095, 0, 99));
  X轴 = (map(analogRead(35), 0, 4095, 0, 99));
  上旋钮 = (map(analogRead(32), 0, 4095, 0, 99));
  下旋钮 = (map(analogRead(33), 0, 4095, 0, 99));
  按钮 = digitalRead(25);
  数据 = String(按钮) + String(Y轴) + String("Y") + String(X轴) + String("X") + String(上旋钮) + String("A") + String(下旋钮) + String("B");
  if (sendMessage(PEER_5CCF7F0A77FB, 数据)) {
  } else {
  }

  timer.run();

}

L298N => rz7889

换成 rz7889驱动

连线图:

ESP8266  --------------  RZ7886电机驱动
VIN  -------------------------  5V
GND  -----------------------  GND
D1  --------------------------   A-1
D2  ---------------------- ----  A-2
D3   --------------------------  B-1
D4   --------------------------  B-2

左边电机接电机驱动A侧，右边电机接电机驱动B侧。
前进时如果哪边电机有反转的情况，将该电机的两电线反接即可。

代码：


#include <ESP8266WiFi.h>
#include <espnow.h>

volatile int enableAvoidCollision;
volatile int joystickYMedian;
volatile int joystickXMedian;
volatile int joystickY;
volatile int joystickX;
volatile int rotationSensorSpeed;
volatile int rotationSensorSpeedAdj;
volatile int connectionLostCountdown;
volatile int motorASpeed;
volatile int motorBSpeed;
volatile int motorASpeedAdj;
volatile int motorBSpeedAdj;
volatile int detour;

unsigned long now = millis();
unsigned long lastTrigger = 0;
#define timeSeconds 10					  
const int trigPin = 12;
const int echoPin = 14;

//define sound speed in cm/uS
#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701

long duration;
float distanceCm;

// Motor A
int motorPinA1 = D1; 
int motorPinA2 = D2; 

// Motor B
int motorPinB1 = D4; 
int motorPinB2 = D5; 

void OnDataRecv(uint8_t * mac, uint8_t *incomingData, uint8_t len) {
  //Serial.printf("Recived Message from MAC:%02X:%02X:%02X:%02X:%02X:%02X\n", mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
  String message = "";
  for (int i = 0; i < static_cast<int>(len); i++) {
    message += String(static_cast<char>(incomingData[i]));
  }
  //Serial.println(message);
  connectionLostCountdown = 10;
  lastTrigger = millis();
  enableAvoidCollision = String(String(message).substring(0,1)).toInt();
  joystickY = String(String(message).substring(1,String(message).indexOf(String("Y")))).toInt();
  joystickX = String(String(message).substring((String(message).indexOf(String("Y")) + 1),String(message).indexOf(String("X")))).toInt();
  rotationSensorSpeed = String(String(message).substring((String(message).indexOf(String("X")) + 1),String(message).indexOf(String("A")))).toInt();
  rotationSensorSpeedAdj = String(String(message).substring((String(message).indexOf(String("A")) + 1),String(message).indexOf(String("B")))).toInt();
  RemoteControlMotorsLogic();
}

void ConnectionLostCountdownTimer() {
  if (connectionLostCountdown > 0) {
    connectionLostCountdown = connectionLostCountdown - 1;

  }
  if (connectionLostCountdown == 0) {
    motorASpeed = 0;
    motorBSpeed = 0;
    enableAvoidCollision = 0;

  }
}

void RemoteControlMotorsLogic() {
  if (joystickY < joystickYMedian - 4) {
    if (joystickX > joystickXMedian + 4) {
      motorASpeed = (map(joystickY, 37, 0, 0, 255)) + (map(joystickX, 49, 99, 0, 255));
      motorBSpeed = (map(joystickY, 37, 0, 0, 255)) - (map(joystickX, 49, 99, 0, 255));

    }
    if (joystickX >= joystickXMedian - 4 && joystickX <= joystickXMedian + 4) {
      motorBSpeed = (map(joystickY, 37, 0, 0, 255));
      motorASpeed = (map(joystickY, 37, 0, 0, 255));

    }
    if (joystickX < joystickXMedian - 4) {
      motorASpeed = (map(joystickY, 37, 0, 0, 255)) + (map(joystickX, 37, 0, 0, (-256)));
      motorBSpeed = (map(joystickY, 37, 0, 0, 255)) - (map(joystickX, 37, 0, 0, (-256)));

    }

  }
  if (joystickY >= joystickYMedian - 4 && joystickY <= joystickYMedian + 4) {
    if (joystickX > joystickXMedian + 4) {
      motorASpeed = (map(joystickX, 49, 99, 0, 255));
      motorBSpeed = (map(joystickX, 49, 99, 0, (-256)));

    }
    if (joystickX >= joystickXMedian - 4 && joystickX <= joystickXMedian + 4) {
      motorASpeed = 0;
      motorBSpeed = 0;

    }
    if (joystickX < joystickXMedian - 4) {
      motorASpeed = (map(joystickX, 37, 0, 0, (-256)));
      motorBSpeed = (map(joystickX, 37, 0, 0, 255));

    }

  }
  if (joystickY > joystickYMedian + 4) {
    if (joystickX > joystickXMedian + 4) {
      motorASpeed = (map(joystickY, 49, 99, 0, (-256))) - (map(joystickX, 49, 99, 0, 255));
      motorBSpeed = (map(joystickY, 49, 99, 0, (-256))) + (map(joystickX, 49, 99, 0, 255));

    }
    if (joystickX >= joystickXMedian - 4 && joystickX <= joystickXMedian + 4) {
      motorBSpeed = (map(joystickY, 49, 99, 0, (-256)));
      motorASpeed = (map(joystickY, 49, 99, 0, (-256)));

    }
    if (joystickX < joystickXMedian - 4) {
      motorASpeed = (map(joystickY, 49, 99, 0, (-256))) - (map(joystickX, 37, 0, 0, (-256)));
      motorBSpeed = (map(joystickY, 49, 99, 0, (-256))) + (map(joystickX, 37, 0, 0, (-256)));

    }

  }
}

float checkdistance() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  // Reads the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  // Calculate the distance
  distanceCm = duration * SOUND_SPEED/2;
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);
  delay(10);
  return distanceCm;
}

void AvoidCollision() {
  if (detour == 0) {
    if (checkdistance() <= 40) {
      detour = 1;

    }

  } else {
    if (checkdistance() >= 80) {
      detour = 0;

    }

  }
  if (detour == 1) {
    analogWrite(5, 120);
    analogWrite(4, 0);
    analogWrite(0, 0);
    analogWrite(2, 120);

  } else {
    analogWrite(5, 150);
    analogWrite(4, 0);
    analogWrite(0, 150);
    analogWrite(2, 0);

  }
}

void setup(){
  Serial.begin(9600);
  enableAvoidCollision = 0;
  joystickYMedian = 43;
  joystickXMedian = 43;
  joystickY = 43;
  joystickX = 43;
  rotationSensorSpeed = 0;
  rotationSensorSpeedAdj = 0;
  connectionLostCountdown = 0;
  motorASpeed = 0;
  motorBSpeed = 0;
  motorASpeedAdj = 0;
  motorBSpeedAdj = 0;
  detour = 0;

  // Set device as a Wi-Fi Station
  WiFi.mode(WIFI_STA);

  //WiFi.persistent(false);
  //WiFi.mode(WIFI_AP);
  //WiFi.disconnect();
  //WiFi.softAP("ESPNOW", nullptr, 3);
  //WiFi.softAPdisconnect(false);

  Serial.print("Device MAC:");
  Serial.println(WiFi.softAPmacAddress());

  // Init ESP-NOW
  if (esp_now_init() != 0) {
    Serial.println("Error initializing ESP-NOW");
    //ESP.restart();
    return;
  }

  // Once ESPNow is successfully Init, we will register for recv CB to
  // get recv packer info
  esp_now_set_self_role(ESP_NOW_ROLE_SLAVE);
  esp_now_register_recv_cb(OnDataRecv);

  pinMode(5, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(0, OUTPUT);
  pinMode(2, OUTPUT);
  pinMode(motorPinA1, OUTPUT);
  pinMode(motorPinA2, OUTPUT);
  pinMode(motorPinB1, OUTPUT);
  pinMode(motorPinB2, OUTPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

void loop(){
  now = millis();
  if(now - lastTrigger > (timeSeconds*1000)) {
    
    ConnectionLostCountdownTimer();
    
  }

  if (rotationSensorSpeedAdj < 40) {
    motorASpeedAdj = (map(rotationSensorSpeedAdj, 0, 39, 120, 3));
    motorBSpeedAdj = (map(rotationSensorSpeedAdj, 0, 39, (-120), (-3)));

  } else {
    if (rotationSensorSpeedAdj > 59) {
      motorASpeedAdj = (map(rotationSensorSpeedAdj, 60, 99, (-3), (-120)));
      motorBSpeedAdj = (map(rotationSensorSpeedAdj, 60, 99, 3, 120));

    } else {
      motorASpeedAdj = 0;
      motorBSpeedAdj = 0;

    }

  }
  if (enableAvoidCollision) {
    AvoidCollision();

  } else {
    // Gear0
    if (rotationSensorSpeed < 33) {
      analogWrite(motorPinA1, 0);
      analogWrite(motorPinA2, 0);
      analogWrite(motorPinB1, 0);
      analogWrite(motorPinB1, 0);

    }
    // Gear1
    if (rotationSensorSpeed >= 33 && rotationSensorSpeed < 66) {
      if (motorBSpeed > 0) {
        analogWrite(motorPinA1, (map(constrain(motorBSpeed + motorBSpeedAdj, 0, 255), 0, 255, 70, 120)));
        analogWrite(motorPinA2, 0);

      } else {
        if (motorBSpeed < 0) {
          analogWrite(motorPinA1, 0);
          analogWrite(motorPinA2, (map(constrain(abs(motorBSpeed - motorBSpeedAdj), 0, 255), 0, 255, 70, 120)));

        } else {
          analogWrite(motorPinA1, 0);
          analogWrite(motorPinA2, 0);

        }

      }
      if (motorASpeed > 0) {
        analogWrite(motorPinB1, (map(constrain(motorASpeed + motorASpeedAdj, 0, 255), 0, 255, 70, 120)));
        analogWrite(motorPinB2, 0);

      } else {
        if (motorASpeed < 0) {
          analogWrite(motorPinB1, 0);
          analogWrite(motorPinB2, (map(constrain(abs(motorASpeed - motorASpeedAdj), 0, 255), 0, 255, 70, 120)));

        } else {
          analogWrite(motorPinB1, 0);
          analogWrite(motorPinB2, 0);

        }

      }

    }
    // Gear2
    if (rotationSensorSpeed >= 66) {
      if (motorBSpeed > 0) {
        analogWrite(motorPinA1, (map(constrain(motorBSpeed + motorBSpeedAdj, 0, 255), 0, 255, 100, 255)));
        analogWrite(motorPinA2, 0);

      } else {
        if (motorBSpeed < 0) {
          analogWrite(motorPinA1, 0);
          analogWrite(motorPinA2, (map(constrain(abs(motorBSpeed - motorBSpeedAdj), 0, 255), 0, 100, 70, 255)));

        } else {
          analogWrite(motorPinA1, 0);
          analogWrite(motorPinA2, 0);

        }

      }
      if (motorASpeed > 0) {
        analogWrite(motorPinB1, (map(constrain(motorASpeed + motorASpeedAdj, 0, 255), 0, 255, 100, 255)));
        analogWrite(motorPinB2, 0);

      } else {
        if (motorASpeed < 0) {
          analogWrite(motorPinB1, 0);
          analogWrite(motorPinB2, (map(constrain(abs(motorASpeed - motorASpeedAdj), 0, 255), 0, 100, 70, 255)));

        } else {
          analogWrite(motorPinB1, 0);
          analogWrite(motorPinB2, 0);

        }

      }

    }

  }

}

ESP32CAM car

ESP32-CAM远程视频监控&底盘控制

Building a Webserver-Controlled Spy Car with ESP32-Cam: A Step Guide

4g小车 2wd esp8266小车+mobile app（MQTTClient）

ESP8266 + SIM7600 → Connects to MQTT Broker via Cellular Batteries (for powering motors and ESP8266) Voltage Regulator (if needed for SIM7600) Web/Mobile App → Publishes commands to MQTT Broker MQTT Broker (e.g., HiveMQ Cloud, EMQX, or Mosquitto) → Routes messages

连线 Wiring

L298N: Connect IN1, IN2, IN3, IN4 to ESP8266 GPIO pins (e.g., D1, D2, D3, D4). Enable pins (ENA, ENB) can be connected to PWM pins (e.g., D5, D6) for speed control.

SIM7600: Connect TX (SIM7600) → RX (ESP8266) Connect RX (SIM7600) → TX (ESP8266)

Power the SIM7600 with 5V/12V (check datasheet). Ensure common ground between all components.

小车代码 ESP8266 Code (MQTT + Cellular)

#include <SoftwareSerial.h>

// Motor Control Pins
#define IN1 D1
#define IN2 D2
#define IN3 D3
#define IN4 D4

// SIM7600 Configuration
SoftwareSerial sim7600(D7, D8); // RX, TX

// Secure MQTT Configuration
const char* BROKER = "broker.emqx.io"; // SSL-enabled public broker
const int PORT = 8883; // Standard MQTT SSL port
const char* CLIENT_ID = "SecureCar_01";
const char* TOPIC = "smartcar/secure/control";
const char* USER = "your_username";
const char* PASS = "your_password";

// SSL Configuration
const char* CA_CERT = ""; // Add CA certificate if required

void setup() {
  Serial.begin(115200);
  sim7600.begin(115200);

  // Initialize Motor Control
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);
  stopCar();

  // Initialize Cellular and Secure MQTT
  setupCellular();
  setupSSL();
  connectMQTT();
}

void loop() {
  checkMQTTMessages();
  // Add periodic keep-alive if needed
}

// ================== SSL Configuration ==================
void setupSSL() {
  // Configure SSL context
  sendAT("AT+CMQTTSSLCFG=0,0", "OK", 2000); // Context 0, SSL version (0=ALL)
  sendAT("AT+CMQTTSSLCFG=0,3,1", "OK", 2000); // Verify mode (1=peer verify)
  sendAT("AT+CMQTTSSLCFG=0,4,1", "OK", 2000); // SSL version (1=TLS 1.2)

  // Load CA certificate (if using)
  if(strlen(CA_CERT) > 0) {
    sendAT("AT+CMQTTSSLCFG=0,1,\"ca.crt\"", "OK", 2000);
    // Use AT+FSUPLOAD to upload certificate first
  }
}

// ================== Secure MQTT Connection ==================
void connectMQTT() {
  sendAT("AT+CMQTTSTART", "OK", 5000);
  
  // Acquire client
  String accqCmd = String("AT+CMQTTACCQ=0,\"") + CLIENT_ID + "\",1";
  sendAT(accqCmd.c_str(), "OK", 5000);

  // Set credentials
  if(strlen(USER) > 0) {
    String userCmd = String("AT+CMQTTUSERNAME=0,") + String(strlen(USER)+2) + ",\"" + USER + "\"";
    sendAT(userCmd.c_str(), "OK", 2000);
  }
  
  if(strlen(PASS) > 0) {
    String passCmd = String("AT+CMQTTPASSWORD=0,") + String(strlen(PASS)+2) + ",\"" + PASS + "\"";
    sendAT(passCmd.c_str(), "OK", 2000);
  }

  // SSL Connection
  String connCmd = String("AT+CMQTTCONNECT=0,\"ssl://") + BROKER + ":" + PORT + "\",60,1";
  sendAT(connCmd.c_str(), "OK", 15000);

  // Subscribe to topic
  String subCmd = String("AT+CMQTTSUB=0,") + String(strlen(TOPIC)+2) + ",1";
  sendAT(subCmd.c_str(), "OK", 5000);
  sendAT(TOPIC, "OK", 5000);
}

// ================== Message Handling ==================
void checkMQTTMessages() {
  sendAT("AT+CMQTTSUBTOPIC=0,100", ">", 2000);
  sendAT("", "OK", 5000);

  while(sim7600.available()) {
    String response = sim7600.readStringUntil('\n');
    if(response.indexOf("+CMQTTSUBRECV: 0") != -1) {
      String payload = sim7600.readStringUntil('\n');
      processCommand(payload.charAt(0));
    }
  }
}

// ================== Motor Control Functions ==================
void moveForward() {
  digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW);
}

void moveBackward() {
  digitalWrite(IN1, LOW); digitalWrite(IN2, HIGH);
  digitalWrite(IN3, LOW); digitalWrite(IN4, HIGH);
}

void turnLeft() {
  digitalWrite(IN1, LOW); digitalWrite(IN2, HIGH);
  digitalWrite(IN3, HIGH); digitalWrite(IN4, LOW);
}

void turnRight() {
  digitalWrite(IN1, HIGH); digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW); digitalWrite(IN4, HIGH);
}

void stopCar() {
  digitalWrite(IN1, LOW); digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW); digitalWrite(IN4, LOW);
}


// ================== AT Command Utility ==================
void sendAT(const char* cmd, const char* expected, int timeout) {
  sim7600.println(cmd);
  uint64_t start = millis();
  String response;
  
  while(millis() - start < timeout) {
    while(sim7600.available()) {
      char c = sim7600.read();
      response += c;
      if(response.indexOf(expected) != -1) {
        Serial.print("Success: ");
        Serial.println(cmd);
        return;
      }
    }
  }
  Serial.print("Timeout: ");
  Serial.println(cmd);
}

Controller控制器网页版

<!DOCTYPE html>
<html>
<head>
    <title>Smart Car Control</title>
    <style>
        .control-pad {
            display: grid;
            grid-template-columns: repeat(3, 100px);
            gap: 10px;
            margin: 50px auto;
            width: 300px;
        }
        button {
            padding: 20px;
            font-size: 1.2em;
            border-radius: 10px;
        }
        .center {
            grid-column: 2;
        }
    </style>
</head>
<body>
    <div class="control-pad">
        <button onclick="sendCommand('F')">↑</button>
        <button class="center" onclick="sendCommand('S')">Stop</button>
        <button onclick="sendCommand('L')">←</button>
        <button onclick="sendCommand('B')">↓</button>
        <button onclick="sendCommand('R')">→</button>
    </div>

    <script src="https://cdnjs.cloudflare.com/ajax/libs/paho-mqtt/1.1.0/paho-mqtt.min.js"></script>
    <script>
        // Use secure WebSocket
        const client = new Paho.MQTT.Client(
        "wss://" + "broker.emqx.io:8084/mqtt", 
        "webClient_" + Math.random().toString(16)
        );

        client.connect({
        onSuccess: () => console.log("Secure connection established"),
        onFailure: (err) => console.error("SSL error:", err.errorMessage)
        });

        function sendCommand(cmd) {
            const message = new Paho.MQTT.Message(cmd);
            message.destinationName = "smartcar/control";
            client.send(message);
        }
    </script>
</body>
</html>

Controller控制器MOBILE APP

参考： ESP8266采用AT指令连接华为云服务器(MQTT固件)

ESP32 远程图传遥控车，基于 MQTT

MCU with 4G LTE Modem. Connecting with the server anywhere!

Troubleshooting

L298N电机驱动蜂鸣声 beep buzz

从这个帖子的评论得到启示

pwm分频可以小点，这样频率高出20000hz就听不到了

在esp32中有配置：ledcAttachChannel(enable1Pin, freq, resolution, pwmChannel); 但是 esp8266 中我没有配置，加上：

// Set PWM frequency to 25 kHz (above the audible range)
  analogWriteFreq(25000);
  
  // Optionally set PWM resolution; default range is 1023 on ESP8266 (10-bit resolution)
  analogWriteRange(1023);

  int dutyCycle = map(desiredValue, 0, 255, 0, 1023); // convert from 0-255 to 0-1023
  analogWrite(enablePin, dutyCycle);

L298N两边电机不一致

原来是一边加了注释，一边没加，可能导致执行快慢有区别，最好是计算好两个轮子的功率后，同时赋值，给pin输出的逻辑之间间隔太久

电机智能往前不能往后

esp8266: // Motor B int motorPinB1 = D2; int motorPinB2 = D3; int enablePinB = D1;

无法后退，可能是D3这个引脚比较特殊: Enters flash mode if LOW at boot，其他的特殊引脚比如： ❌ GPIO2 (D4) → Must be HIGH at boot. May cause instability. ❌ GPIO9 (SD2) & GPIO10 (SD3) → Connected to Flash Memory. ❌ GPIO16 (D0) → No PWM support, only Digital I/O.

A fatal esptool.py error occurred: Failed to connect to ESP8266: Timed out waiting for packet header

由于前面遇到的问题，现在超声模块的连接是：

D3  -------------------------   Trigger Pin
D4  -------------------------   Echo Pin

遇到这个问题我一度以为是板子坏了，结果拔掉跟超声模块的连接后问题消失，怀疑是pin的连接问题：

Note: D4 HIGH at boot connected to on-board LED, boot fails if pulled LOW

On the ESP8266, D3 is GPIO0 and D4 is GPIO2, and the ESP8266’s boot process requires these pins to be in specific states:

Here’s what likely happened:

Trigger on GPIO0: As an output, the trigger pin might be driven LOW (or pulled low by the HC-SR04 module) during boot. This violates the boot condition (GPIO0 must be HIGH), causing the ESP8266 to fail to boot properly or to enter flash mode—resulting in failed uploads. Echo on GPIO2: Even if the echo pin behaves normally, if GPIO0 isn’t in the correct state, the board won’t boot as expected.

解决方案： AI 回答说可以： Use an external pull-up resistor (e.g., 10kΩ to 3.3V) to keep it HIGH at boot. 不过我尝试没有成功，

然后自己尝试了调换 D3 和 D4 成功了

D4  -------------------------   Trigger Pin
D3  -------------------------   Echo Pin

至于原因，这是AI的回答： Swapping the pins can change how the sensor’s output affects the ESP8266’s boot conditions—even though both GPIO0 (D3) and GPIO2 (D4) ideally should be high at boot. Here’s a more detailed explanation:

  1. Different Pin Roles (Input vs. Output):

In your original setup, you had the Trigger on D3 (GPIO0) and the Echo on D4 (GPIO2). The Trigger pin is an output from the ESP8266, so you actively drive it. In contrast, the Echo pin is an input that the HC-SR04 drives. Even if both pins are required to be high at boot, an input pin (Echo) might be influenced by the sensor’s characteristics (for example, if the sensor’s output is low or floating) more than an output pin (Trigger), which is actively driven by your code.

  1. Internal Pull-up Differences:

GPIO0 (D3) typically has a weak internal pull-up, but when it is used as an input (Echo), it might more reliably be pulled high by an external resistor or the sensor’s circuitry. GPIO2 (D4), while also needing to be high at boot, can be more sensitive to external circuitry. If the sensor’s Echo output isn’t actively driven high (or if it has a tendency to be low when idle), it might force GPIO2 to remain low, preventing a normal boot.

  1. Sensor Output Characteristics:

The HC-SR04’s Echo pin may not output a solid HIGH level when idle—its output can be weak or even low if nothing is triggering it. When you connect this potentially “low” signal to GPIO2 (D4), the ESP8266 might interpret that as a violation of its boot condition. Swapping the pins means the Echo signal is now on GPIO0 (D3). In this configuration, if GPIO0’s internal pull-up (or an external pull-up if used) manages to keep the pin high despite the sensor’s output, the board can boot normally. Practical Outcome:

Original configuration (Trigger on D3, Echo on D4): The Echo signal on D4 may be inadvertently pulling GPIO2 low during boot, causing upload failures. Swapped configuration (Trigger on D4, Echo on D3): The Echo signal on D3 is less likely to drop below the necessary HIGH threshold (due to internal/external pull-up properties or the sensor’s output characteristics), allowing the ESP8266 to boot and upload code properly.

In short, swapping D3 and D4 works because the behavior of the sensor’s Echo output on those two pins is different—likely due to differences in internal pull-up strength and how the sensor interacts with each pin. Even though both pins are required to be high at boot, the sensor’s output may affect one pin (GPIO2/D4) more adversely than the other (GPIO0/D3) when left in its default state.

ESP8266无法启动

发现 serial monitor没有任何输出，setup和loop貌似没有执行，怀疑根本没启动，发现是因为为了解决上面上传代码的问题调换了接线：

D4  -------------------------   Trigger Pin
D3  -------------------------   Echo Pin

现在代码可以上传了，但是无法启动

Note: D3 connected to FLASH button, boot fails if pulled LOW

AI回答原因：

The ESP8266’s boot process is very sensitive to the state of certain GPIO pins, particularly GPIO0 (commonly D3) and GPIO2 (commonly D4). Here’s what that means and why your wiring might be affecting boot-up:

D3 (GPIO 0) is connected to the Echo pin: The HC-SR04’s Echo pin is an output that starts LOW when idle (before a measurement is triggered). This could pull GPIO 0 LOW during boot, preventing the ESP8266 from starting normally. D4 (GPIO 2) is connected to the Trigger pin: The Trigger pin is an input to the HC-SR04 and should be floating or HIGH when idle, so this is less likely to cause an issue unless there’s a wiring problem. The most probable culprit is D3 (GPIO 0) being held LOW by the Echo pin, forcing the ESP8266 into a non-bootable state.

尝试解决方案：

AI说可以尝试 pull up 10kΩ resistor，就是在D3和vcc（3.3v）之间加一个10kΩ的电阻，加上后还是没反应，我测了下此时D3的电压，只有0.2v左右， 又换成220Ω的，只升了一点点0.25v With the 10kΩ pull-up, D3 was 0.2V. With 220Ω, it’s now 0.25V—slightly higher, but still far below the ~2V needed for the ESP8266 to boot normally.

Voltage Divider Effect: The HC-SR04 Echo pin, when idle (LOW), acts like a low-impedance path to GND (likely <100Ω). With a 220Ω pull-up to 3.3V, the voltage on D3 is determined by the divider: V_D3 = 3.3V * (R_Echo / (220Ω + R_Echo)), where R_Echo is the Echo pin’s effective resistance when LOW. Solving for R_Echo: 0.25V = 3.3V * (R_Echo / (220Ω + R_Echo)) => R_Echo ≈ 18Ω.

The HC-SR04 Echo pin’s LOW state has an effective impedance of ~18Ω—extremely low! This explains why even 220Ω (15mA pull-up current) can’t lift D3 above 0.25V.

Why 220Ω Isn’t Enough Current: 220Ω provides 3.3V / 220Ω = 15mA to pull D3 HIGH. The Echo pin sinks almost all of this to GND through its ~18Ω impedance, leaving D3 near 0V.

多少欧合适？ Idea: Use a lower resistance to provide more current and raise D3’s voltage above 2V. Calculation: To get >2V with R_Echo ≈ 18Ω: V_D3 = 3.3V * (18Ω / (R_pullup + 18Ω)) > 2V => R_pullup < 11.7Ω.

潜在问题 Problem: Even 110Ω isn’t enough, and 10Ω (330mA!) risks overheating the resistor or stressing the HC-SR04’s Echo pin (max current ~20-40mA).

所以pull up方案即使可以，高出这么多的电流有可能会让传感器挂掉

最终解决方案

D4  -------------------------   Trigger Pin
D0  -------------------------   Echo Pin

附： 好奇pull up方案如果成功，HC-SR04如何在正常工作的时候把这个pin拉回低电平？

据说是跟内部的transistor有关 When LOW: The HC-SR04 turns on an internal NPN transistor or MOSFET connected between Echo and GND. This creates a low-impedance path to ground

  1. Idle with Pull-Up (D3 Case)

220Ω Pull-Up: With D3 at 0.25V, the 220Ω (15mA to 3.3V) and ~18Ω to GND form a divider, as we calculated. The transistor’s LOW state wins, but the pull-up keeps D3 above 0V.

Stronger Pull-Up: If you used a much stronger pull-up (e.g., 10Ω, 330mA to 3.3V) to get D3 to 2V when idle: V_D3 = 3.3V * (18Ω / (10Ω + 18Ω)) ≈ 2.12V.

This would indeed hold D3 above 2V, making boot possible. Problem: During operation, the same ~18Ω transistor would still pull against the 10Ω pull-up, keeping D3 at ~2.12V when LOW—not low enough for the ESP8266 to reliably detect as a logic LOW (<0.8V).

  1. Transistor’s Actual Behavior ~18Ω is an Estimate: The 18Ω was derived from the idle state with a 220Ω pull-up. In reality, the transistor’s ON resistance (R_ON) is likely lower (e.g., 5-10Ω), and the 0.25V included some measurement or wiring factors. Without a pull-up (like on D0), it pulls closer to 0V. Active Drive: When the HC-SR04 switches Echo LOW, the transistor is fully ON, aiming for ~0V. With no pull-up, it achieves this. With a pull-up, the voltage depends on the resistor’s strength.

  2. Can It Pull LOW If Idle is 2V or 3.3V? Let’s test your hypothesis with scenarios:

Scenario 1: Idle at 3.3V (Diode Isolation) Setup: Echo → Diode → D3, 220Ω pull-up to 3.3V. Idle D3 = 3.3V (diode blocks LOW). Operation: Trigger: Echo goes HIGH, diode conducts, D3 ≈ 3.3V (or adjusted by divider). Post-Pulse: Echo goes LOW (0V), but diode blocks, D3 stays 3.3V via pull-up. Issue: pulseIn() won’t work—it needs a HIGH-to-LOW transition. The diode prevents the LOW state, so duration = 0 or infinite. Fix: Remove the diode or use a buffer—D3 must see the LOW.

Scenario 2: Idle at 2V (Strong Pull-Up) Setup: 10Ω pull-up to 3.3V, Echo on D3, idle V_D3 ≈ 2.12V (18Ω vs. 10Ω). Operation: Trigger: Echo HIGH, D3 ≈ 3.3V. Post-Pulse: Echo LOW, D3 back to 2.12V. Issue: 2.12V isn’t LOW (<0.8V) for the ESP8266. pulseIn() might not detect the transition, or it’ll misread the duration. Reality Check: Your D0 setup worked because no pull-up kept LOW near 0V.

所以结论是行不通，即使可能成功boot成功，但是后续会阻止echo从高电平到低电平 无法正常工作

esp8266不断重启

观察到 esp8266 后面的蓝色led rear blue led 总会突然熄灭

When motors or other loads suddenly draw extra current, the supply voltage can drop. This can cause the ESP8266 (and its peripherals, like the LED) to reset or behave erratically.

我用的是一个废旧的充电宝加上一个升压模块，很有可能是输出不稳定，当电机工作时会突然导致重启

Make sure your power supply can handle the peak current required by the motors. Consider adding a capacitor (e.g., a 470µF or 1000µF electrolytic capacitor) across the power supply near the ESP8266 to help smooth out transients.

esp-now遥控延迟

Possible Causes:

Optimizing Code: Simplify message parsing (e.g., using sscanf() instead of multiple String operations) and try to offload heavy tasks or optimize collision detection logic to reduce delays.