Arduino: Serial Port Communication

📁 File Structure

UART_Voice/
├── UART_Voice.ino    # Main program
├── bsp_uart.hpp         # Header file (protocol frames and function declarations)
├── bsp_uart.cpp         # Implementation file
└── README.md              # This tutorial

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🔌 Hardware Connection

Connecting to the Voice Module

💡 Note: RX and TX need to be cross-connected!

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🔧 Build and Upload

Step 1: Open the Arduino IDE

1. Open the UART_Voice.ino file

2. Select your development board model (e.g. Arduino Uno)

3. Select the corresponding serial port

Step 2: Build and Upload

1. Click the ✔️ button to build

2. Click the ➡️ button to upload to the development board

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📡 Serial Port Test

Open the serial monitor in the Arduino IDE

• Baud rate: 115200

• Line ending: None

Expected Output

After power-on you should see:

UART Voice Module Initialized

Say the wake word and command words to the module, and the corresponding IDs will be output:

ID: 1
ID: 2
ID: 10

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📚 Protocol Frame Format

Example: reading the command ID = 10

FE EF 00 0A EE

Example: sending a command word playback

FE EF D3 00 EE

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📚 BSP Interface Description

UART_Init()

void UART_Init(void);

Function: Initialize the serial port (baud rate 115200)

Example:

void setup() {
  UART_Init();
}

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UART_ReadCommand()

int UART_ReadCommand(void);

Function: Read the command ID recognized by the voice module

Return value:

• 0 - no command recognized

• 1~254 - command ID

• -1 - no new data

Example:

int id = UART_ReadCommand();
if (id > 0) {
  Serial.print("识别到命令: ");
  Serial.println(id);
}

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UART_SetPassiveVoice()

void UART_SetPassiveVoice(uint8_t voiceID);

Function: Set the passive playback voice

Parameter:

• 0x00 - passive response phrase type

Example:

UART_SetPassiveVoice(0x00);
delay(200);

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UART_SetFunctionVoice()

void UART_SetFunctionVoice(uint8_t voiceID);

Function: Set the function word playback voice

Parameter:

• 0x00 - function word playback phrase type

Example:

UART_SetFunctionVoice(0x00);
delay(200);

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UART_SetCommandVoice()

void UART_SetCommandVoice(uint8_t voiceID);

Function: Set the command word playback voice

Parameter:

• 0x00 - command word playback phrase type

Example:

UART_SetCommandVoice(0x00);
delay(200);

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🎯 Main Program Logic Description

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

  Serial.println("UART Voice Module Initialized");

  UART_SetCommandVoice(0x00);  // Play the command word voice on power-up
  delay(200);
}

void loop() {
  int commandId = UART_ReadCommand();

  if (commandId >= 0) {
    // Filter out invalid values to prevent duplicate output
    if (commandId != 0 && commandId != 255 && commandId != lastCommandId) {
      Serial.print("ID: ");
      Serial.println(commandId);
      lastCommandId = commandId;

      // Example: control the playback based on the recognized command
      if (commandId == 1) {
        UART_SetCommandVoice(0x00);  // Command 1 recognized, play command word voice
      } else if (commandId == 2) {
        UART_SetCommandVoice(0x00);  // Command 2 recognized, play command word voice
      }
    } else if (commandId == 0 || commandId == 255) {
      if (lastCommandId != 0) {
        lastCommandId = 0;  // Reset state
      }
    }
  }

  delay(50);
}

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🔍 Troubleshooting

Q1: No output at all

Possible causes:

1. RX/TX are reversed

2. GND is not common

3. The module is not powered

4. Wrong baud rate

Solutions:

• Confirm that D10 connects to the module TX and D11 to the module RX (cross connection)

• Confirm the GND connection

• Confirm the 5V supply is normal

• Confirm that the serial port baud rate is 115200

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Q2: The serial port only shows garbled characters

Possible causes:

1. Baud rate mismatch

2. The module is not powering up properly

Solutions:

• Confirm that the serial monitor baud rate is 115200

• Press the module reset button once

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Q3: It outputs "ID: 255" or "ID: 0"

Note: this is normal

• 0 = no command recognized

• 255 = no new data

These values are already filtered out in the code and normally will not be output. If you see them output, the code is not taking effect.

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💡 Advantages of the BSP Architecture

Clear Code Layering

• bsp_uart.hpp - view the declarations only, not the implementation

• bsp_uart.cpp - the concrete implementation details

• UART_Voice.ino - concerned only with business logic

Easy to Port

If you switch to another platform (such as STM32 or ESP32), you only need to modify the implementation of bsp_uart.cpp; the main program does not need to change.

Easy to Maintain

Changes to UART-related code are made only in bsp_uart.cpp; change once, effective everywhere.

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🚀 Extended Function Examples

Example 1: Trigger Different Playback Based on Different Commands

if (commandId == 1) {
  UART_SetCommandVoice(0x00);      // Play command word
} else if (commandId == 2) {
  UART_SetFunctionVoice(0x00);     // Play function word
} else if (commandId == 3) {
  UART_SetPassiveVoice(0x00);      // Play passive phrase
}

Example 2: Control an LED

if (commandId == 10) {
  digitalWrite(LED_PIN, LOW);    // Turn off the light
  UART_SetCommandVoice(0x00);     // Play confirmation voice
}

Example 3: Control a Motor

if (commandId == 11) {
  motor_stop();
  UART_SetCommandVoice(0x00);     // Play confirmation voice
}

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