SW4STM32C datasheet(61/99 Pages) STMICROELECTRONICS

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AN4989

Printf debugging

HAL_UART_Transmit(&UartHandle, (uint8_t *)&ch, 1, 0xFFFF);

return ch;

}

Without syscall.c integrated, a customized _write function has to be defined:

int _write(int file, char *ptr, int len)

{

int DataIdx;

for (DataIdx = 0; DataIdx < len; DataIdx++){ __io_putchar( *ptr++ );}

return len;

}

Refer to STM32Cube provided example UART_Printf() available for almost all STM32

Series. An example is available in STM32Cube_FW_F3_V1.7.0\Projects\

STM32F303ZE-Nucleo\Examples\UART\UART_Printf.

Caution:

USART word length includes parity which is not the case for most of UART terminal. Word

length 8 with parity require 7 bits + parity on terminal side to match.

VCP does not support Word length of 7 bits and below (whatever the parity). Table 5 gives

examples of compatible configurations:

7.3

Printf via SWO/SWV

Serial Wire Output (SWO) is single pin, asynchronous serial communication channel

available on Cortex-M3/M4/M7 and supported by the main debugger probes.

It is using the ITM (instrumentation trace macrocell) module of the Cortex Core-Sight.

The asynchronous mode (SWO) requires 1 extra pin and is available on all packages for

STM32 based on Cortex-M3, -M4, and -M7.

It is only available if a Serial Wire mode is used. It is not available in JTAG mode.

By default, this pin is NOT assigned. It can be assigned by setting the TRACE_IOEN and

TRACE_MODE bits in the Debug MCU configuration register (DBGMCU_CR). This

configuration has to be done by the debugger host.

Refer to the related chapter of STMicroelectronics reference manual.

In debug context it can be a good alternative to UART in system where pinout constraints

are strong (alternate function preempting UART GPIOs).

Table 5. STM32 USART vs. PC terminal WordLength example

STM32 UART

PC Terminal

Word Length: 8, Parity: Odd

Data: 7, Parity: Odd

Word Length: 8, Parity: None

Data: 8, Parity: None

Word Length: 9, Parity: Odd

Data 8, Parity: Odd

Word Length: 7, Parity: Odd/None

Not Working with VCP

SW4STM32C Datasheet(PDF) 61 Page - STMicroelectronics

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