JavaME RaspBerryPi UART 无法从 RS485 接收数据 [英] JavaME RaspBerryPi UART can't receive data from RS485

问题描述

我尝试将我的 raspberry pi(带有 raspbian weezy)与条形 LED 模块连接起来.为此，我使用 RBPi 的 UART 连接来与 RS485 条形连接进行通信.

I try to connect my raspberry pi (with raspbian weezy) with a strip LED module. To do this, I use the UART connection of RBPi in order to communicate with RS485 strip connection.

我的问题:我可以(是的，我可以)发送数据，但我没有收到 ACK 或其他任何东西.然而，我的条形 LED 模块将数据帧发送到 RBPi(我可以在示波器上看到它).

My trouble : I can (yes I can) send data but I don't received ACK or anything else. However my strip LED module send data frame to the RBPi (I can see it on oscilloscope).

我认为这是由于程序打开UART连接时出现的以下错误.否:以下错误是由于非用户权限所致

I think it's due to the following error that appears when the program opened UART connection. NO : The following error is due to an non-user permission

[错误] [DAAPI] iso=-1: 无法打开/dev/mem

[ERROR] [DAAPI] iso=-1:cannot open /dev/mem

好吧，但我没有收到消息...

Well, But I don't receive message...

结束编辑

我编写了以下 javaME 代码来执行此操作:

I write the following javaME code to do this :

UARTConfig config = new UARTConfig((int)Integer.valueOf(this.getPortCom()),(int)Integer.valueOf(this.getPortCom()), this.getBaudrate(),
                                                this.getBitsperchar(), this.getUARTParity(), getStopBits(), UARTConfig.FLOWCONTROL_NONE);

this.uart = (UART)DeviceManager.open(config);

InputStream serialInputStream = Channels.newInputStream(uart);
BufferedReader serialBufferedReader = new BufferedReader(new InputStreamReader(serialInputStream));

 this.tSerialOutput = new Thread( new SerialWriter( Channels.newOutputStream(uart) ) );
 this.tSerialOutput.start();
 this.tSerialInput = new Thread( new SerialReader( serialBufferedReader ));
 this.tSerialInput.start();

this"是我管理串行通信的类.

"this" is my class which manage serial communication.

错误信息是在DeviceManager.open"之后得到的我已遵循以下票证的建议:https://community.oracle.com/message/12513726

The error message is getting after the "DeviceManager.open" I have follow the recommendation of the following ticket : https://community.oracle.com/message/12513726

但这并不是我问题的真正答案(我认为...)

But it's not really the answer of my issue (I think...)

我不知道......所以请帮帮我^^

I have no idea.... So please, help me ^^

推荐答案

首先，您必须确保 Linux 控制台尚未使用串行端口.以下是禁用此功能的方法:

First, you must be sure Serial Port is not already used by Linux Console. Here is how to disable this:

编辑 /etc/inittab 并通过在它前面添加一个 # 字符来禁用以下行

Edit /etc/inittab and disable the following line by adding a # character in front of it

T0:23:respawn:/sbin/getty -L ttyAMA0 115200 vt100

然后重启.

如果这仍然不起作用，那么您可以尝试使用提升的权限执行 JavaME 运行时:

If this is still not working, then you may try to execute JavaME runtime with elevated privileges:

sudo ./runSuite.sh <yourapp>

如果这有效，则说明某处存在权限问题.

If this is working, there is a permission problem somewhere.

最后，您应该尝试获取最新版本的 JavaME(目前为 8.1).

Finally, you should try to get latest version of JavaME (currently, it is 8.1).

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