class iodevice
{
public:
    virtual void putchar(const uint8_t &byte) = 0;
            void send(char const* buffer);
            void puts(char const* buffer);
            void printf(char const *format, ...);
protected:
    iodevice() {}
};

void iodevice::send(char const* buffer)
{
    while(*buffer)
        putchar(*buffer++);
}


void iodevice::puts(char const * string)
{
    send(string);
    send("\r\n");
}

void iodevice::printf(char const * format, ...)
{
    const size_t BUFFER_SIZE = 80;
    char Buffer[BUFFER_SIZE];

    va_list args;
    va_start (args, format);
    vsnprintf (Buffer, BUFFER_SIZE, format, args);
    va_end (args);
    send(Buffer);
}

class system_uart_t : public iodevice
{
public:
    void putchar(const uint8_t &byte) { UART1.send(byte); }
};

class user_uart_t : public iodevice
{
public:
    void putchar(const uint8_t &byte) { UART2.send(byte); }
};


system_uart_t System_uart;
user_uart_t User_uart;
void test()
{
      System_uart.printf("Tipa test %d", 1);
      User_uart.printf("Tipa test %d", 2);

     iodevice * pOutput = &User_uart;

     pOutput->printf("слава мне, победителю %s!!!", "драконов")

}

<span style="font-family: monospace;"><span style="font-weight: bold;">static char format_buff[DEBUG_BUFF_SIZE];

void UartPrintf(const char *args, ...)
{
   uint32_t len;
   va_list ap;
   va_start(ap, args);
   len = vsnprintf(format_buff,sizeof(format_buff),args,ap);
   va_end(ap);
   UartWrite(format_buff,len);  
}

</span></span>