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How to get the TX status in Java Midlet on EHS6 | Telit Cinterion IoT Developer Community

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luke_maxon's picture
luke_maxon

June 24, 2015 - 3:54am, 3253 views

We are using EHS6 module and its ASC0 for serial port comms. A function we developed would need to know whether the messages have been sent out (buffer emptied) after the midlet writes the messages to the serial port. We haven't found a method in the Java document that can get this status? Does anyone have suggestions/ideas?   

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Jure's picture
Jure
Jun 24 2015 - 8:12am

You could make sure that msg was sent with flush():

public void flush() throws IOException

Flushes this output stream and forces any buffered output bytes to be written out. The general contract of flush is that calling it is an indication that, if any bytes previously written have been buffered by the implementation of the output stream, such bytes should immediately be written to their intended destination.

If the intended destination of this stream is an abstraction provided by the underlying operating system, for example a file, then flushing the stream guarantees only that bytes previously written to the stream are passed to the operating system for writing; it does not guarantee that they are actually written to a physical device such as a disk drive.

The flush method of OutputStream does nothing.

(source: https://docs.oracle.com/javase/7/docs/api/java/io/OutputStream.html)

But I am not sure what did they mean with: "The flush method of OutputStream does nothing."

Regards,

Jure

Bartłomiej Gemalto Moderator's picture
Bartłomiej Gema...
Jun 24 2015 - 2:31pm

Hello,

As Java is a high-level programming language there is no method for controlling directly the underlying buffers of the operating system and serial interface.

If this is critical for you to know when the data have been really sent out, you would probably need some extra hardware for that. Flashing the stream will not give you this information and in case of OutputStream it actually does nothing according to the documentation. 

Regards,

Bartłomiej

luke_maxon's picture
luke_maxon
Jun 25 2015 - 9:34am

Thanks for all of your feedback. 

We did try Flush() and it didn't work as Bartłomiej suggested. We also thought of using RTS signal in HW flow control mode but RTS wasn't the signal we really need as it would only be inactive (high) when input buffer was full (not for the non empty output buffer).

We looked at Oracle JAVA ME Doc website, in the DIO API package, there are quite a few UART methods available, inlcuding signal controls and event listeners. 

http://docs.oracle.com/javame/8.0/api/dio/api/index.html

For UART APIs, there is UARTEvent class that encapsulates events fired by devices that implement the UART interface and there is an event field OUTPUT_BUFFER_EMPTY. Don't know wheter this can help or not. Also, the Java platform for the EHS6 may not have the DIO package included though.

Thanks.

Luke

Bartłomiej Gemalto Moderator's picture
Bartłomiej Gema...
Jul 1 2015 - 2:17pm

The EHS6 Java platform does not include DIO package and there's no API to access the low level UART interface from Java.