Debug Console

Overview

This chapter describes the programming interface of the debug console driver.

The debug console enables debug log messages to be output via the specified peripheral with frequency of the peripheral source clock and base address at the specified baud rate. Additionally, it provides input and output functions to scan and print formatted data.

Function groups

Initialization

To initialize the debug console, call the DbgConsole_Init() function with these parameters. This function automatically enables the module and the clock.

/*
 * @brief Initializes the the peripheral used to debug messages.
 *
 * @param baseAddr      Indicates which address of the peripheral is used to send debug messages.
 * @param baudRate      The desired baud rate in bits per second.
 * @param device        Low level device type for the debug console, can be one of:
 *                      @arg DEBUG_CONSOLE_DEVICE_TYPE_UART,
 *                      @arg DEBUG_CONSOLE_DEVICE_TYPE_LPUART,
 *                      @arg DEBUG_CONSOLE_DEVICE_TYPE_LPSCI,
 *                      @arg DEBUG_CONSOLE_DEVICE_TYPE_USBCDC.
 * @param clkSrcFreq    Frequency of peripheral source clock.
 *
 * @return              Whether initialization was successful or not.
 */
status_t DbgConsole_Init(uint32_t baseAddr, uint32_t baudRate, uint8_t device, uint32_t clkSrcFreq)

Selects the supported debug console hardware device type, such as

DEBUG_CONSOLE_DEVICE_TYPE_NONE   
DEBUG_CONSOLE_DEVICE_TYPE_LPSCI  
DEBUG_CONSOLE_DEVICE_TYPE_UART   
DEBUG_CONSOLE_DEVICE_TYPE_LPUART 
DEBUG_CONSOLE_DEVICE_TYPE_USBCDC 

After the initialization is successful, stdout and stdin are connected to the selected peripheral. The debug console state is stored in the debug_console_state_t structure, such as shown here.

typedef struct DebugConsoleState
{
    uint8_t                     type; 
    void*                       base; 
    debug_console_ops_t         ops;  
} debug_console_state_t;

This example shows how to call the DbgConsole_Init() given the user configuration structure.

uint32_t uartClkSrcFreq = CLOCK_GetFreq(BOARD_DEBUG_UART_CLKSRC);

DbgConsole_Init(BOARD_DEBUG_UART_BASEADDR, BOARD_DEBUG_UART_BAUDRATE, DEBUG_CONSOLE_DEVICE_TYPE_UART, uartClkSrcFreq);

Advanced Feature

The debug console provides input and output functions to scan and print formatted data.

• Support a format specifier for PRINTF following this prototype " %[flags][width][.precision][length]specifier", which is explained below

flags	Description
-	Left-justified within the given field width. Right-justified is the default.
+	Forces to precede the result with a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a - sign.
(space)	If no sign is written, a blank space is inserted before the value.
#	Used with o, x, or X specifiers the value is preceded with 0, 0x, or 0X respectively for values other than zero. Used with e, E and f, it forces the written output to contain a decimal point even if no digits would follow. By default, if no digits follow, no decimal point is written. Used with g or G the result is the same as with e or E but trailing zeros are not removed.
0	Left-pads the number with zeroes (0) instead of spaces, where padding is specified (see width sub-specifier).

Width	Description
(number)	A minimum number of characters to be printed. If the value to be printed is shorter than this number, the result is padded with blank spaces. The value is not truncated even if the result is larger.
*	The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

.precision	Description
.number	For integer specifiers (d, i, o, u, x, X) − precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with leading zeros. The value is not truncated even if the result is longer. A precision of 0 means that no character is written for the value 0. For e, E, and f specifiers − this is the number of digits to be printed after the decimal point. For g and G specifiers − This is the maximum number of significant digits to be printed. For s − this is the maximum number of characters to be printed. By default, all characters are printed until the ending null character is encountered. For c type − it has no effect. When no precision is specified, the default is 1. If the period is specified without an explicit value for precision, 0 is assumed.
.*	The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

length	Description
Do not support

specifier	Description
d or i	Signed decimal integer
f	Decimal floating point
F	Decimal floating point capital letters
x	Unsigned hexadecimal integer
X	Unsigned hexadecimal integer capital letters
o	Signed octal
b	Binary value
p	Pointer address
u	Unsigned decimal integer
c	Character
s	String of characters
n	Nothing printed

• Support a format specifier for SCANF following this prototype " %[*][width][length]specifier", which is explained below

*	Description
An optional starting asterisk indicates that the data is to be read from the stream but ignored. In other words, it is not stored in the corresponding argument.

width	Description
This specifies the maximum number of characters to be read in the current reading operation.

length	Description
hh	The argument is interpreted as a signed character or unsigned character (only applies to integer specifiers: i, d, o, u, x, and X).
h	The argument is interpreted as a short integer or unsigned short integer (only applies to integer specifiers: i, d, o, u, x, and X).
l	The argument is interpreted as a long integer or unsigned long integer for integer specifiers (i, d, o, u, x, and X) and as a wide character or wide character string for specifiers c and s.
ll	The argument is interpreted as a long long integer or unsigned long long integer for integer specifiers (i, d, o, u, x, and X) and as a wide character or wide character string for specifiers c and s.
L	The argument is interpreted as a long double (only applies to floating point specifiers: e, E, f, g, and G).
j or z or t	Not supported

specifier	Qualifying Input	Type of argument
c	Single character: Reads the next character. If a width different from 1 is specified, the function reads width characters and stores them in the successive locations of the array passed as argument. No null character is appended at the end.	char *
i	Integer: : Number optionally preceded with a + or - sign	int *
d	Decimal integer: Number optionally preceded with a + or - sign	int *
a, A, e, E, f, F, g, G	Floating point: Decimal number containing a decimal point, optionally preceded by a + or - sign and optionally followed by the e or E character and a decimal number. Two examples of valid entries are -732.103 and 7.12e4	float *
o	Octal Integer:	int *
s	String of characters. This reads subsequent characters until a white space is found (white space characters are considered to be blank, newline, and tab).	char *
u	Unsigned decimal integer.	unsigned int *

The debug console has its own printf/scanf/putchar/getchar functions which are defined in the header file.

int DbgConsole_Printf(const char *fmt_s, ...);  
int DbgConsole_Putchar(int ch);                 
int DbgConsole_Scanf(const char *fmt_ptr, ...); 
int DbgConsole_Getchar(void);                   

This utility supports selecting toolchain's printf/scanf or the MCUXpresso SDK printf/scanf.

#if SDK_DEBUGCONSOLE    /* Select printf, scanf, putchar, getchar of SDK version. */
#define PRINTF                 DbgConsole_Printf
#define SCANF                  DbgConsole_Scanf
#define PUTCHAR                DbgConsole_Putchar
#define GETCHAR                DbgConsole_Getchar
#else                   /* Select printf, scanf, putchar, getchar of toolchain. */
#define PRINTF                 printf
#define SCANF                  scanf
#define PUTCHAR                putchar
#define GETCHAR                getchar
#endif /* SDK_DEBUGCONSOLE */

Typical use case

Some examples use the PUTCHAR & GETCHAR function

ch = GETCHAR();
PUTCHAR(ch);

Some examples use the PRINTF function

Statement prints the string format.

PRINTF("%s %s\r\n", "Hello", "world!");

Statement prints the hexadecimal format/

PRINTF("0x%02X hexadecimal number equivalents 255", 255);

Statement prints the decimal floating point and unsigned decimal.

PRINTF("Execution timer: %s\n\rTime: %u ticks %2.5f milliseconds\n\rDONE\n\r", "1 day", 86400, 86.4);

Some examples use the SCANF function

PRINTF("Enter a decimal number: ");
SCANF("%d", &i);
PRINTF("\r\nYou have entered %d.\r\n", i, i);
PRINTF("Enter a hexadecimal number: ");
SCANF("%x", &i);
PRINTF("\r\nYou have entered 0x%X (%d).\r\n", i, i);

Print out failure messages using KSDK __assert_func:

void __assert_func(const char *file, int line, const char *func, const char *failedExpr)
{
    PRINTF("ASSERT ERROR \" %s \": file \"%s\" Line \"%d\" function name \"%s\" \n", failedExpr, file , line, func);
    for (;;)
    {}
}

Note:

To use 'printf' and 'scanf' for GNUC Base, add file 'fsl_sbrk.c' in path: ..\{package}\devices\{subset}\utilities\fsl_sbrk.c to your project.

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