Question: How to reinitialise UART for mbed_debug?

[amitchone]

Description of defect

Hi there,

I am using the debug() function to print a bunch of info/error messages when using the debug build profile. Under specific circumstances I instantiate a UARTSerial object in the follow way, where the TX/RX pins are the same as used for the mbed_debug UART:

UARTSerial *_serial;
_serial = new UARTSerial(TX, RX, BAUD);

My question is a simple one. Is there an explicit function call I can make to re-instantiate the UART used by mbed_debug after deleting my _serial object?

Thanks,
Adam

Target(s) affected by this defect ?

N/A

Toolchain(s) (name and version) displaying this defect ?

N/A

What version of Mbed-os are you using (tag or sha) ?

5.15.0 - 64853b3

What version(s) of tools are you using. List all that apply (E.g. mbed-cli)

ARM Compiler 6.13
Clangd 8.0.1
Mbed Studio 0.8.1

How is this defect reproduced ?

N/A

[amitchone]

Or, is there an object I can use instead of the UARTSerial object that I create? I'm using it with the ATCmdParser.

[ciarmcom]

Internal Jira reference: https://jira.arm.com/browse/MBOTRIAGE-2530

[AGlass0fMilk]

Hi @amitchone, you may want to check out mbed_override_console and mbed_file_handle here:

mbed-os/platform/mbed_retarget.h

Lines 115 to 181 in 5863415

	/** Applications may implement this to change stdin, stdout, stderr.
	*
	* This hook gives the application a chance to specify a custom FileHandle
	* for the console.
	*
	* If this is not provided or returns NULL, the console will be specified
	* by mbed_target_override_console, else will default to serial - see
	* mbed_target_override_console for more details.
	*
	* Example using BufferedSerial:
	* @code
	* FileHandle *mbed::mbed_override_console(int) {
	* static BufferedSerial my_serial(D0, D1);
	* return &my_serial;
	* }
	* @endcode
	*
	* Example using SingleWireOutput:
	* @code
	* FileHandle *mbed::mbed_override_console(int) {
	* static SerialWireOutput swo;
	* return &swo;
	* }
	* @endcode
	*
	* Example using arm semihosting:
	* @code
	* FileHandle *mbed::mbed_override_console(int fileno) {
	* static LocalFileSystem fs("host");
	* if (fileno == STDIN_FILENO) {
	* static FileHandle *in_terminal;
	* static int in_open_result = fs.open(&in_terminal, ":tt", O_RDONLY);
	* return in_terminal;
	* } else {
	* static FileHandle *out_terminal;
	* static int out_open_result = fs.open(&out_terminal, ":tt", O_WRONLY);
	* return out_terminal;
	* }
	* }
	* @endcode
	*
	* @param fd file descriptor - STDIN_FILENO, STDOUT_FILENO or STDERR_FILENO
	* @return pointer to FileHandle to override normal stream otherwise NULL
	*/
	FileHandle *mbed_override_console(int fd);
	/** Look up the Mbed file handle corresponding to a file descriptor
	*
	* This conversion function permits an application to find the underlying
	* FileHandle object corresponding to a POSIX file descriptor.
	*
	* This allows access to specialized behavior only available via the
	* FileHandle API.
	*
	* Example of saving power by disabling console input - for buffered serial,
	* this would release the RX interrupt handler, which would release the
	* deep sleep lock.
	* @code
	* mbed_file_handle(STDIN_FILENO)->enable_input(false);
	* @endcode
	*
	* @param fd file descriptor
	* @return FileHandle pointer
	* NULL if descriptor does not correspond to a FileHandle (only
	* possible if it's not open with current implementation).
	*/
	FileHandle *mbed_file_handle(int fd);

It looks like mbed_debug uses printf to print information out through stdout. Using the above functions you can access/retarget the serial instance used for stdout.

Let me know if you have any other questions.

[0xc0170]

Thanks @AGlass0fMilk for the help.

I'll close this as this is a question (use forum please).

[amitchone]

Thanks @AGlass0fMilk, mbed_file_handle was exactly what I was looking for.