情景
一般硬件设备提供的内置串口数量是有限的，当串口不够用时，就需要通过USB来外接这些设备
CH341是一种芯片，它可以将以串口方式进行通信的设备，转接到USB口上进行通信
使用该方案，需要购买对应的CH341转换器，将串口设备转接到USB口上，转换器支持一个USB口接多个串口设备
准备
引入CH34XMultiUARTDriver.jar
这是一个串口转USB的驱动，支持CH341等型号的芯片
核心代码
//连接CH34X设备CH34X.connect();CH34X.read();//定期读取CH34X设备参数CH34xHandler.read();WorkThread.postByLoop(CH34xHandler::write);
package com.android.driver.ch34x;import android.app.PendingIntent;import android.content.Intent;import android.hardware.usb.UsbDevice;import android.hardware.usb.UsbManager;import android.os.Looper;import mons.monApplication;import mons.android.bin.Bytes;import mons.android.code.Console;import mons.android.helper.exception.BizException;import mons.android.thread.Threads;import mons.android.thread.WorkThread;import java.util.ArrayList;import java.util.List;import cn.wch.lib.ch34xMultiDriver;import cn.wch.lib.ch34xMultiManager;@SuppressWarnings("all")public class CH34X {protected static UsbManager service;protected static ch34xMultiManager manager;protected static List<UsbDevice> deviceList;protected static final List<Reader> readers = new ArrayList();protected static boolean connected = false;//判断设备是否连接public static boolean connected() {return connected;}//检查权限public static boolean checkPermission() {boolean hasPermission = true;for (UsbDevice device : deviceList) {boolean ret = service.hasPermission(device);if (!ret)hasPermission = false;}Console.info("CH34X Permission Check : " + hasPermission);return hasPermission;}//检测并连接设备public static void connect() {service = CommonApplication.ctx.getSystemService(UsbManager.class);manager = new ch34xMultiManager(CommonApplication.ctx, service);WorkThread.postByLoop("#CH34X连接线程", () -> {try {if (connected)return;if (Looper.myLooper() == null)Looper.prepare();//搜索设备manager.initDeviceList();deviceList = manager.usbDeviceList;Console.info("CH34X Find Device : " + deviceList.size());//检查并申请权限if (!checkPermission()) {for (UsbDevice device : deviceList) {Intent intent = new Intent("cn.wch.USB_PERMISSION");PendingIntent pendingIntent = PendingIntent.getBroadcast(CommonApplication.ctx, 0, intent, 0);service.requestPermission(device, pendingIntent);}}//打开设备boolean isDeviceOpen = true;for (UsbDevice device : deviceList) {boolean ret = manager.OpenUsbDevice(device);if (!ret)isDeviceOpen = false;}Console.info("CH34X Open Device : " + isDeviceOpen);//连接失败if (!isDeviceOpen)throw BizException.of("CH34X Connect Fail");//连接成功connected = true;Console.info("CH34X Connect Success");//配置设备boolean isDeviceConfigured = true;int index = 0;for (UsbDevice device : deviceList) {ch34xMultiDriver driver = manager.ch34xDriverList.get(index);index++;boolean ret = driver.SetConfig(9600, (byte) 1, (byte) 8, (byte) 0, (byte) 0);if (!ret)isDeviceConfigured = false;}Console.info("CH34X Configure Device : " + isDeviceConfigured);} catch (Throwable e) {manager.CloseAll();Console.error("CH34X Connect Fail");}Threads.sleep(3 * 1000L);});}//读数据public static void read() {WorkThread.post(() -> {final byte[] buffer = new byte[10 * 1024];while (true) {if (!connected)continue;try {int index = 0;for (UsbDevice device : deviceList) {ch34xMultiDriver driver = manager.ch34xDriverList.get(index);manager.SemDeviceList.acquire();int length = driver.ReadData(buffer, 10 * 1024);manager.SemDeviceList.release();if (length > 0) {byte[] newBytes = Bytes.copy(buffer, 0, length);onMessageRead(index, newBytes);}index++;}Threads.sleep(500);} catch (Throwable e) {Console.error("CH34X Read Fail");}}});}//数据读取成功public static void onMessageRead(int deviceIndex, byte[] bytes) {String hex = Bytes.byteArrayToHex(bytes);Console.info("CH34X Read", "Device-" + deviceIndex, hex);for (Reader reader : readers)reader.onMessageRead(deviceIndex, bytes);}//写数据public static void write(Integer deviceIndex, byte[] bytes) {if (!connected)return;if (deviceIndex == null)deviceIndex = 0;try {int index = 0;for (UsbDevice device : deviceList) {if (index != deviceIndex)continue;ch34xMultiDriver driver = manager.ch34xDriverList.get(index);manager.SemDeviceList.acquire();int ret = driver.WriteData(bytes, bytes.length);manager.SemDeviceList.release();String hex = Bytes.byteArrayToHex(bytes);Console.info("CH34X Write", "Device-" + deviceIndex, hex);index++;}} catch (Throwable e) {Console.error("CH34X Write Fail");}}//添加读取回调public static void addReader(Reader reader) {readers.add(reader);}//移除读取回调public static void removeReader(Reader reader) {readers.remove(reader);}}
源码下载
Android CH34X串口转USB.zip
