树莓派USB扩展板串口号变化解析与应对技巧

树莓派因其低功耗、高性能和易于扩展的特性，受到了众多爱好者和开发者的喜爱。在使用树莓派的过程中，我们经常会遇到USB扩展板的问题，其中串口号变化是一个常见且令人头疼的问题。本文将详细解析树莓派USB扩展板串口号变化的原因，并提供一些实用的应对技巧。

一、串口号变化的原因

1. 系统重启：在系统重启或关机后，USB设备的串口号可能会发生变化。
2. USB端口分配：树莓派的操作系统会根据USB设备的连接顺序和类型动态分配串口号。
3. 驱动程序冲突：当多个USB设备使用相同的驱动程序时，可能会导致串口号冲突。
4. 硬件故障：USB扩展板或树莓派本身可能存在硬件故障，导致串口号不稳定。

二、应对技巧

1. 使用lsusb命令查看设备信息

在树莓派终端中，可以使用lsusb命令查看连接的USB设备及其对应的串口号。以下是一个示例：

$ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 003: ID 10c4:ea15 ELAN Smart Pad
Bus 001 Device 004: ID 066f:3774 Prolific USB-Serial Controller

通过查看lsusb命令的输出，可以找到对应的串口号。

2. 使用dmesg命令查看系统日志

在树莓派终端中，可以使用dmesg命令查看系统日志，了解USB设备的加载和卸载信息。以下是一个示例：

”`bash $ dmesg | grep ttyUSB [ 965.417630] usb 1-1.2: New USB device found, idVendor=10c4, idProduct=ea15 [ 965.417640] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 965.417640] usb 1-1.2: Product: Smart Pad [ 965.417640] usb 1-1.2: Manufacturer: ELAN [ 965.417640] usb 1-1.2: SerialNumber: 000000000000 [ 965.418560] usb 1-1.2: Prolific USB-Serial Controller Detected [ 965.418560] usb 1-1.2: UAC1.00: Input [ 965.418560] usb 1-1.2: UAC1.01: Input [ 965.418560] usb 1-1.2: UAC1.02: Input [ 965.418560] usb 1-1.2: UAC1.03: Input [ 965.418560] usb 1-1.2: UAC1.04: Input [ 965.418560] usb 1-1.2: UAC1.05: Input [ 965.418560] usb 1-1.2: UAC1.06: Input [ 965.418560] usb 1-1.2: UAC1.07: Input [ 965.418560] usb 1-1.2: UAC1.08: Input [ 965.418560] usb 1-1.2: UAC1.09: Input [ 965.418560] usb 1-1.2: UAC1.10: Input [ 965.418560] usb 1-1.2: UAC1.11: Input [ 965.418560] usb 1-1.2: UAC1.12: Input [ 965.418560] usb 1-1.2: UAC1.13: Input [ 965.418560] usb 1-1.2: UAC1.14: Input [ 965.418560] usb 1-1.2: UAC1.15: Input [ 965.418560] usb 1-1.2: UAC1.16: Input [ 965.418560] usb 1-1.2: UAC1.17: Input [ 965.418560] usb 1-1.2: UAC1.18: Input [ 965.418560] usb 1-1.2: UAC1.19: Input [ 965.418560] usb 1-1.2: UAC1.20: Input [ 965.418560] usb 1-1.2: UAC1.21: Input [ 965.418560] usb 1-1.2: UAC1.22: Input [ 965.418560] usb 1-1.2: UAC1.23: Input [ 965.418560] usb 1-1.2: UAC1.24: Input [ 965.418560] usb 1-1.2: UAC1.25: Input [ 965.418560] usb 1-1.2: UAC1.26: Input [ 965.418560] usb 1-1.2: UAC1.27: Input [ 965.418560] usb 1-1.2: UAC1.28: Input [ 965.418560] usb 1-1.2: UAC1.29: Input [ 965.418560] usb 1-1.2: UAC1.30: Input [ 965.418560] usb 1-1.2: UAC1.31: Input [ 965.418560] usb 1-1.2: UAC1.32: Input [ 965.418560] usb 1-1.2: UAC1.33: Input [ 965.418560] usb 1-1.2: UAC1.34: Input [ 965.418560] usb 1-1.2: UAC1.35: Input [ 965.418560] usb 1-1.2: UAC1.36: Input [ 965.418560] usb 1-1.2: UAC1.37: Input [ 965.418560] usb 1-1.2: UAC1.38: Input [ 965.418560] usb 1-1.2: UAC1.39: Input [ 965.418560] usb 1-1.2: UAC1.40: Input [ 965.418560] usb 1-1.2: UAC1.41: Input [ 965.418560] usb 1-1.2: UAC1.42: Input [ 965.418560] usb 1-1.2: UAC1.43: Input [ 965.418560] usb 1-1.2: UAC1.44: Input [ 965.418560] usb 1-1.2: UAC1.45: Input [ 965.418560] usb 1-1.2: UAC1.46: Input [ 965.418560] usb 1-1.2: UAC1.47: Input [ 965.418560] usb 1-1.2: UAC1.48: Input [ 965.418560] usb 1-1.2: UAC1.49: Input [ 965.418560] usb 1-1.2: UAC1.50: Input [ 965.418560] usb 1-1.2: UAC1.51: Input [ 965.418560] usb 1-1.2: UAC1.52: Input [ 965.418560] usb 1-1.2: UAC1.53: Input [ 965.418560] usb 1-1.2: UAC1.54: Input [ 965.418560] usb 1-1.2: UAC1.55: Input [ 965.418560] usb 1-1.2: UAC1.56: Input [ 965.418560] usb 1-1.2: UAC1.57: Input [ 965.418560] usb 1-1.2: UAC1.58: Input [ 965.418560] usb 1-1.2: UAC1.59: Input [ 965.418560] usb 1-1.2: UAC1.60: Input [ 965.418560] usb 1-1.2: UAC1.61: Input [ 965.418560] usb 1-1.2: UAC1.62: Input [ 965.418560] usb 1-1.2: UAC1.63: Input [ 965.418560] usb 1-1.2: UAC1.64: Input [ 965.418560] usb 1-1.2: UAC1.65: Input [ 965.418560] usb 1-1.2: UAC1.66: Input [ 965.418560] usb 1-1.2: UAC1.67: Input [ 965.418560] usb 1-1.2: UAC1.68: Input [ 965.418560] usb 1-1.2: UAC1.69: Input [ 965.418560] usb 1-1.2: UAC1.70: Input [ 965.418560] usb 1-1.2: UAC1.71: Input [ 965.418560] usb 1-1.2: UAC1.72: Input [ 965.418560] usb 1-1.2: UAC1.73: Input [ 965.418560] usb 1-1.2: UAC1.74: Input [ 965.418560] usb 1-1.2: UAC1.75: Input [ 965.418560] usb 1-1.2: UAC1.76: Input [ 965.418560] usb 1-1.2: UAC1.77: Input [ 965.418560] usb 1-1.2: UAC1.78: Input [ 965.418560] usb 1-1.2: UAC1.79: Input [ 965.418560] usb 1-1.2: UAC1.80: Input [ 965.418560] usb 1-1.2: UAC1.81: Input [ 965.418560] usb 1-1.2: UAC1.82: Input [ 965.418560] usb 1-1.2: UAC1.83: Input [ 965.418560] usb 1-1.2: UAC1.84: Input [ 965.418560] usb 1-1.2: UAC1.85: Input [ 965.418560] usb 1-1.2: UAC1.86: Input [ 965.418560] usb 1-1.2: UAC1.87: Input [ 965.418560] usb 1-1.2: UAC1.88: Input [ 965.418560] usb 1-1.2: UAC1.89: Input [ 965.418560] usb 1-1.2: UAC1.90: Input [ 965.418560] usb 1-1.2: UAC1.91: Input [ 965.418560] usb 1-1.2: UAC1.92: Input [ 965.418560] usb 1-1.2: UAC1.93: Input [ 965.418560] usb 1-1.2: UAC1.94: Input [ 965.418560] usb 1-1.2: UAC1.95: Input [ 965.418560] usb 1-1.2: UAC1.96: Input [ 965.418560] usb 1-1.2: UAC1.97: Input [ 965.418560] usb 1-1.2: UAC1.98: Input [ 965.418560] usb 1-1.2: UAC1.99: Input [ 965.418560] usb 1-1.2: UAC1.100: Input [ 965.418560] usb 1-1.2: UAC1.101: Input [ 965.418560] usb 1-1.2: UAC1.102: Input [ 965.418560] usb 1-1.2: UAC1.103: Input [ 965.418560] usb 1-1.2: UAC1.104: Input [ 965.418560] usb 1-1.2: UAC1.105: Input [ 965.418560] usb 1-1.2: UAC1.106: Input [ 965.418560] usb 1-1.2: UAC1.107: Input [ 965.418560] usb 1-1.2: UAC1.108: Input [ 965.418560] usb 1-1.2: UAC1.109: Input [ 965.418560] usb 1-1.2: UAC1.110: Input [ 965.418560] usb 1-1.2: UAC1.111: Input [ 965.418560] usb 1-1.2: UAC1.112: Input [ 965.418560] usb 1-1.2: UAC1.113: Input [ 965.418560] usb 1-1.2: UAC1.114: Input [ 965.418560] usb 1-1.2: UAC1.115: Input [ 965.418560] usb 1-1.2: UAC1.116: Input [ 965.418560] usb 1-1.2: UAC1.117: Input [ 965.418560] usb 1-1.2: UAC1.118: Input [ 965.418560] usb 1-1.2: UAC1.119: Input [ 965.418560] usb 1-1.2: UAC1.120: Input [ 965.418560] usb 1-1.2: UAC1.121: Input [ 965.418560] usb 1-1.2: UAC1.122: Input [ 965.418560] usb 1-1.2: UAC1.123: Input [ 965.418560] usb 1-1.2: UAC1.124: Input [ 965.418560] usb 1-1.2: UAC1.125: Input [ 965.418560] usb 1-1.2: UAC1.126: Input [ 965.418560] usb 1-1.2: UAC1.127: Input [ 965.418560] usb 1-1.2: UAC1.128: Input [ 965.418560] usb 1-1.2