UART RX stream stops when receiving special characters

[panpwr]

Hello,

I am using an interrupt-driven UART port with MQX 4.0.

Here are the strings I see using an external terminal console (the expected result):

Terminal:

at+iRP1

ID809b16 11.6.2012

I/OK

And here is what i get from UART:

at+iRP1\r\n

ID809b16 11.6.2012\r\n

I      <=== Missing chars: "/OK"

The second batch actually comes through fine, even with the special char "/":

Terminal = UART:

at+iRP1

I/OK

However, the 3rd batch stops at a special character as well:

Terminal:

at+iRP3

0801 9.6.2009

I/OK

UART:

at+iRP3

0801 9   <=== Missing chars: ".6.2009"

             <=== Missing chars: "I/OK"

This is my receptions code:

if (_io_fstatus(ch))

{

   //Pending char in UART

   rx_uart = fgetc(connect_one_ch);

}

I've opened the UART descriptor using io_open, with no flags. What am I missing here? Please notice that the problem persists when I try to receive 3 lines from UART. Is there a special property I need to set?

Thanks,
Lior.

[Luis_Garabo]

Hi Panpwr,

It is possible that you are using the default open flags. This is the default:

#define BSP_DEFAULT_IO_OPEN_MODE (pointer) (IO_SERIAL_XON_XOFF | IO_SERIAL_TRANSLATION | IO_SERIAL_ECHO)

I suggest you add this line to the user_config.h file:

#define BSP_DEFAULT_IO_OPEN_MODE (pointer) (IO_SERIAL_XON_XOFF | IO_SERIAL_ECHO)

You will see that the flag IO_SERIAL_TRANSLATION was removed. Don't forget to recompile the BSP library before compiling again your application. I hope this helps.

Have a nice day.

-Garabo

[panpwr]

Unfortunately, this doesn't work - I get some of the characters, and other i don't.

I get the same results, when changing from open mode from IO_SERIAL_XON_XOFF to IO_SERIAL_NON_BLOCKING.

Also, adding delays between tx and rx change the results a bit:

*** Receiving First batch of strings: ***

Terminal:

AT+iRP1

ID809b16 11.6.2012

I/OK

Everything was received correctly from UART.

*** Receiving Second batch of strings: ***

Terminal:

+++I/ERROR (056)

And here is what i get from UART:

+++ <=== Missing chars: "I/ERROR (056)"

Missing characters when reading from UART.

*** Receiving Third of strings: ***

Terminal:

AT+iRP1

ID809b16 11.6.2012

I/OK

And here is what i get from UART:

IAT+iRP1 <=== A spare char: "I"

ID809b16 11.6.2012

I/OK

Spare character when reading from UART - probably one of the missing chars from the previous batch.

It seems that something with the buffer or reception timings is wrong.

Do you have any suggestions?

Thanks,

Lior.

[panpwr]

More questions regarding the UART:

1. Am I using the UART driver properly? Do I really need to poll the device for data arrival in serial-interrupt mode?

2. Can't I use a callback function that will notify me whenever a specific event occurs ((e.g., "\n" character arrives)? If so, then what is the difference between serial-polled & serial-interrupt modes?

[Luis_Garabo]

Let me answer to each or your questions:

1. You can find that the appnote AN4022 shows the right usage of the UART interrupt driver. It is similar to what you are doing but with a IOCTL() call.

2. You cannot set a callback function. The interrupt is happening at the driver level. You could set events and set them from the application.

I hope this helps.

Best Regards,

-Garabo

[panpwr]

Hello,

I've read AN4022 "IP Camera and USB Snapshot with MQX", and couldn't see any code which uses the UART driver (only initialization in user_config.h).

You've mentioned that I can use Events to notify the application about different occurrences. How can I notify the application that it needs to check the UART buffer?

Thanks,

Lior.