Printf Via Swo/Swv; Table 5. Stm32 Usart Vs. Pc Terminal Wordlength Example - STMicroelectronics STM32 Application Note

AN4989
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).
examples of compatible configurations:
Word Length: 7, Parity: Odd/None
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
Word Length: 8, Parity: Odd
Word Length: 8, Parity: None
Word Length: 9, Parity: Odd
AN4989 Rev 3
Printf debugging
Table 5
PC Terminal
Data: 7, Parity: Odd
Data: 8, Parity: None
Data 8, Parity: Odd
Not Working with VCP
gives
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117