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hhaji1
Beginner
2,651 Views

Uart method of byte read and write.

I have a question about mraa.

There are uart methods of writeStr and readStr in java.

I would like to use uart methods of byte read and write.

Do I have to modify the mraa source (uart.java?) file?

Where Is the source file in java?

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11 Replies
idata
Community Manager
53 Views

Hi hajime_s,

Thank you for your interest in the Intel Edison Platform.

You shouldn't have to change the mraa library, please try to update it by using the following commands:

1. root@edison:~# ifconfig wlan0 up

2. root@edison:~# echo "src mraa-upm http://iotdk.intel.com/repos/1.1/intelgalactic" > /etc/opkg/mraa-upm.conf

3. root@edison:~# opkg update

4. root@edison:~# opkg install libmraa0

 

Also please check this link were they use the mraa library to access the UART functionality: http://www.tektyte.com/docs/docpages/edison-reference/UART.html UART on the Intel Edison — Tektyte 1.0 documentation.

I will be waiting for your reply, have a nice day.

Best Regards,

 

-Jose
hhaji1
Beginner
53 Views

I tried the commands on my edison.

But I can not compile my java program,

The method write(String, int) is undefined for the type Uart

I am using the iss-iot-launcher.bat.

I can use mraa_uart_write() function in C language, but I can not find the same function in Java language.

Best regards,

Hajime.

idata
Community Manager
53 Views

Hi Hajime,

Can you please try this code https://github.com/intel-iot-devkit/mraa/blob/master/examples/java/UartExample.java mraa/UartExample.java at master · intel-iot-devkit/mraa · GitHub, I already try it in the Intel System Studio and it compile with no errors. Please let me know your results.

I will be waiting for your reply, have a nice day.

Best Regards,

 

-Jose
hhaji1
Beginner
53 Views

Hi Jose,

Thank you for your quick reply.

The had tried the code. It worked well.

I would like to use 'write bytes' instead of 'write string'.

I would like to use 'read bytes' instead of 'read string'.

Best regards,

Hajime.

idata
Community Manager
53 Views

Hi Hajime,

 

 

Could you please hand me your code that you mention in one of your previous reply. This in order to replicate your issue. I will be waiting for your reply.

 

 

We hope you have a nice day!

 

 

Best Regards,

 

-Jose
hhaji1
Beginner
53 Views

Hi Jose,

Thank you for your quick reply.

I would like to use the function for C languages in Java.

int mraa_uart_write( mraa_uart_context dev,const char * buf,size_t length )

There is not the same function in Java.

Best regards,

Hajime

idata
Community Manager
53 Views

Hi Hajime,

I'm sorry, I understood that you had written code and had some compilation problems. I investigated for a function equivalent to int mraa_uart_write ( mraa_uart_context dev,const char * buf,size_t length ) in java. I found this link http://iotdk.intel.com/docs/master/mraa/java/classmraa_1_1_uart.html# ac9a4bea13d1bbc3c6821cc0c208c7e84 mraa: Uart Class Reference were it shows all the available functions in java, as you can see there is no equivalent function in java. I would suggest to use the uart.writeStr() and use a decoder in order to obtain the bytes you are looking to transmit. I hope you find this information useful.

I will be waiting for your reply, we hope you have a nice day.

Best Regards,

 

-Jose
hhaji1
Beginner
53 Views

Hi Jose,

I would like to write binary data (0xFF, 0xFF, 0xFA, 0xAF...) via uart.

Best regards,

Hajime.

idata
Community Manager
53 Views

Hi Hajime,

As you know char functions consist of 2 bytes, so if you want to send a byte you can use this function stringBytes[i] = (byte) stringChars[i] & 0x00FF. Refer to this link for more information (http://stackoverflow.com/questions/9139453/how-to-convert-char-to-byte java - How to convert char to byte? - Stack Overflow ). I hope you find this information useful.

I will be waiting for your reply, I hope you have a nice day.

Best Regards,

 

-Jose.
hhaji1
Beginner
53 Views

Hi Jose,

Thank you very much.

Best regards,

Hajime

idata
Community Manager
53 Views

Hi Hajime,

Always happy to help, if you have any more questions please don't hesitate to contact us.

Have a nice day!

Best Regards,

 

-Jose.
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