Arduino RP2040 两个CDC虚拟串口通讯

---

• 🎬通讯效果演示：
  
• 🌿基于Earle F. Philhower的固件开发平台： https://github.com/earlephilhower/arduino-pico
• 🔖USB配置参考：https://arduino-pico.readthedocs.io/en/latest/usb.html
• ✅本例程使用的开发板：YD-RP2040版(源地YD-RP2040)
  

📑功能说明

🖋两个CDC虚拟串口通讯，不受波特率限制，物理上只占用一个USB接口。

🛠参数配置

• 🔧编译并运行此例程需要将默认参数中的USB Stack配置为Adafruit TinyUSB库才可以实现多个USB设备的挂载。
  
• 🔨修改Adafruit TinyUSB库中的默认参数
  

🔖个人的文件路径参考：

C:\Users\Administrator\AppData\Local\Arduino15\packages\rp2040\hardware\rp2040\3.3.0\libraries\Adafruit_TinyUSB_Arduino\src\arduino\ports\rp2040

• • 👉🏻修改宏CFG_TUD_CDC 参数为2，默认是只生成一个CDC虚拟串口。

//--------------------------------------------------------------------
// Device Configuration
//--------------------------------------------------------------------

#define CFG_TUD_ENDOINT0_SIZE 64

#define CFG_TUD_CDC 2   //默认值是1，只生成一个虚拟CDC端口，2代表生成2个CDC虚拟端口 
#define CFG_TUD_MSC 1
#define CFG_TUD_HID 2
#define CFG_TUD_MIDI 1
#define CFG_TUD_VENDOR 1

• 🌿程序烧录成功后，将生成2个CDC虚拟串口：
  

• ✨如果是第一次使用Arduino平台开发，那么需要按住RP2040开发板上的Boot按键，通过USB数据线连接到电脑USB端口，会出现一个64MB的虚拟U盘，此再编译上传代码即可。

📝例程代码

• 🔖本例程代码可以在固件库自带的例程示例中找到：
  

/*
    This example demonstrates the use of multiple USB CDC/ACM "Virtual
    Serial" ports

    Written by Bill Westfield (aka WestfW), June 2021.
    Copyright 2021 by Bill Westfield
    MIT license, check LICENSE for more information
*/


/* The example creates two virtual serial ports. Text entered on
   any of the ports will be echoed to the all ports with
    - all lower case in port0 (Serial)
    - all upper case in port1
需要修改库中的配置参数：libraries/Adafruit_TinyUSB_Arduino/src/arduino/ports/rp2040/tusb_config_rp2040.h
#define CFG_TUD_CDC 2 //默认值是1，只生成一个虚拟CDC端口，2代表生成2个CDC虚拟端口
   Requirement:
    The max number of CDC ports (CFG_TUD_CDC) has to be changed to at least 2.
    Config file is located in Adafruit_TinyUSB_Arduino/src/arduino/ports/{platform}/tusb_config_{platform}.h
    where platform is one of: nrf, rp2040, samd

    NOTE: Currnetly multiple CDCs on ESP32-Sx is not yet supported.
    An PR to update core/esp32/USBCDC and/or pre-built libusb are needed.
    We would implement this later when we could.
*/

#include <Adafruit_TinyUSB.h>

#define ARDUINO_ARCH_RP2040
#define LED LED_BUILTIN

// Create 2nd instance of CDC Ports.
#ifdef ARDUINO_ARCH_ESP32
#error "Currnetly multiple CDCs on ESP32-Sx is not yet supported. An PR to update core/esp32/USBCDC and/or pre-built libusb are needed."
// for ESP32, we need to specify instance number when declaring object
Adafruit_USBD_CDC USBSer1(1);
#else
Adafruit_USBD_CDC USBSer1;
#endif

void setup() {
  pinMode(LED, OUTPUT);

  Serial.begin(115200);

  // check to see if multiple CDCs are enabled
  if ( CFG_TUD_CDC < 2 ) {
    digitalWrite(LED, HIGH); // LED on for error indicator

    while (1) {//如果没有修改Adafruit_TinyUSB_Arduino/src/arduino/ports/tusb_config_rp2040.h中的CFG_TUD_CDC参数，程序将停留在这里面运行
      Serial.printf("CFG_TUD_CDC must be at least 2, current value is %u\n", CFG_TUD_CDC);
      Serial.println("  Config file is located in Adafruit_TinyUSB_Arduino/src/arduino/ports/{platform}/tusb_config_{platform}.h");
      Serial.println("  where platform is one of: nrf, rp2040, samd");
      digitalWrite(LED, HIGH);
      delay(1000);
      digitalWrite(LED, LOW);
      delay(1000);
    }
  }

  // initialize 2nd CDC interface
  USBSer1.begin(115200);

  while (!Serial || !USBSer1) {
    if (Serial) {
      Serial.println("Waiting for other USB ports");
    }

    if (USBSer1) {
      USBSer1.println("Waiting for other USB ports");
    }

    delay(1000);
  }

  Serial.print("You are port 0\n\r\n0> ");
  USBSer1.print("You are port 1\n\r\n1> ");
}

int LEDstate = 0;

void loop() {
  int ch;

  ch = Serial.read();
  if (ch > 0) {
    printAll(ch);
  }

  ch = USBSer1.read();
  if (ch > 0) {
    printAll(ch);
  }

  if (delay_without_delaying(500)) {
    LEDstate = !LEDstate;
    digitalWrite(LED, LEDstate);
  }
}

// print to all CDC ports
void printAll(int ch) {
  // always lower case
  Serial.write(tolower(ch));

  // always upper case
  USBSer1.write(toupper(ch));
}

// Helper: non-blocking "delay" alternative.
boolean delay_without_delaying(unsigned long time) {
  // return false if we're still "delaying", true if time ms has passed.
  // this should look a lot like "blink without delay"
  static unsigned long previousmillis = 0;
  unsigned long currentmillis = millis();
  if (currentmillis - previousmillis >= time) {
    previousmillis = currentmillis;
    return true;
  }
  return false;
}