No serial output after retargetting and calling fopen() - c++

Question

I'm trying to implement a basic application on an embedded device using lwIP.
I got the basic project set up, the retarget-ing works as expected.
However when I add lwIP into the project and call lwip_init() I have no more output. If I leave out the call to lwip_init() everything is back to normal.
What's more interesting, is that if I call fopen() the same behavior appears as before, I have no other output on the serial. I get no output no matter if I use the retarget-ed printf() function or if I use the driver's function USART_SendData().
What did I got wrong?
I posted below the retarget.c file and my Main.cpp (if I un-comment either BLOCK 1 or BLOCK 2, I have no more output) along with the initialization code.
Note: the retarget-ed functions send data to USART3 and USART_SendData() sends it to USART1.
I also tried to use the ITM port for debugging, but I get the same behavior.
retarget.c:
#include <stdio.h>
#include <LibSTM/stm32f10x_usart.h>
#include <rt_sys.h>
#pragma import(__use_no_semihosting_swi)
struct __FILE { int handle; };
FILE __stdout;
FILE __stdin;
FILE __stderr;
FILE *__aeabi_stdin;
FILE *__aeabi_stdout;
FILE *__aeabi_stderr;
int fputc(int ch, FILE *f)
{
while (!(USART3->SR & 0x0080));
USART3->DR = ch;
return (ch);
}
int ferror(FILE *f)
{
return EOF;
}
void _ttywrch(int ch)
{
fputc(ch, stdout);
}
void _sys_exit(int return_code)
{
label: goto label;
}
//retargeting since otherwise lwIP inclusion produces errors
//http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka3844.html
#define DEFAULT_HANDLE 0x100
const char __stdin_name[] = "my_stdin";
const char __stdout_name[] = "my_stdout";
const char __stderr_name[] = "my_stderr";
int _sys_write(FILEHANDLE fh, const unsigned char * buf, unsigned len, int mode){
int i;
for(i=0;i<len;i++)
{
fputc(buf[i], stdout);
}
return 0;
}
FILEHANDLE _sys_open(const char* name, int openmode){
return DEFAULT_HANDLE;
}
int _sys_istty(FILEHANDLE fh){
return 0;
}
int _sys_seek(FILEHANDLE fh, long pos){
return -1;
}
long _sys_flen(FILEHANDLE fh){
return 0;
}
int _sys_close(FILEHANDLE fh){
return 0;
}
int _sys_ensure(FILEHANDLE fh){
return 0;
}
main.cpp:
#include <HW/HWSetup.h>
#include <stdio.h>
#include "lwip/init.h"
int main()
{
HWSetup();
printf("Start!\r\n");
/* //BLOCK 1
FILE *f;
f = fopen("foobar", "r");
*/
/* //BLOCK 2
lwip_init();
*/
printf("End!\r\n");
while(1){
USART_SendData(USART1, 'x');
}
}
HWSetup.cpp:
#include <HW/HWSetup.h>
#include <stdio.h>
void SetupGPIO()
{
RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO | RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB, ENABLE);
}
void SetupTraces()
{
GPIO_InitTypeDef GPIO_InitStructure;
// Trace GPIO
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);
// Trace USART
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);
USART_InitTypeDef USART_InitStructure;
USART_InitStructure.USART_BaudRate = 921600;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Tx;
USART_Init(USART3, &USART_InitStructure);
USART_Cmd(USART3, ENABLE);
}
void SetupUSART_RS232()
{
GPIO_InitTypeDef GPIO_InitStructure;
// USART1 GPIO
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD;
GPIO_Init(GPIOA, &GPIO_InitStructure);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
USART_InitTypeDef USART_InitStructure;
USART_InitStructure.USART_BaudRate = 115200;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No ;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_Init(USART1,&USART_InitStructure);
}
void HWSetup()
{
SetupGPIO();
SetupUSART_RS232();
SetupTraces();
}
I also tried debugging the code, but after I step in at BX R0 (which I expect to get me into main()) I just have to stop debugging since I cannot see where it's going, nor I have any other control over the debugger:
; Reset handler
Reset_Handler PROC
EXPORT Reset_Handler [WEAK]
IMPORT __main
IMPORT SystemInit
LDR R0, =SystemInit
BLX R0
LDR R0, =__main
BX R0
ENDP

Answer 1

The following code worked for me with a LPC1788 and µVision5 with and without microlib:
//retarget minimum requirements to work with printf
#include <stdio.h>
#include <rt_misc.h>
#ifndef __MICROLIB
#pragma import(__use_no_semihosting_swi) // some projects need this, some don't like it
#endif
#include <rt_sys.h>
extern void $Super$$_sys_open(void);
extern int sendchar(int ch); //needed for printf
extern int getch(void); //needed for scanf
FILEHANDLE $Sub$$_sys_open(const char *name, int openmode)
{
return 1; /* everything goes to the same output */
}
extern void $Super$$_sys_close(void);
int $Sub$$_sys_close(FILEHANDLE fh)
{
return 0;
}
extern void $Super$$_sys_write(void);
int $Sub$$_sys_write(FILEHANDLE fh, const unsigned char *buf,
unsigned len, int mode)
{
//your_device_write(buf, len);
return 0;
}
extern void $Super$$_sys_read(void);
int $Sub$$_sys_read(FILEHANDLE fh, unsigned char *buf,
unsigned len, int mode)
{
return -1; /* not supported */
}
extern void $Super$$_ttywrch(void);
void $Sub$$_ttywrch(int ch)
{
//char c = ch;
//your_device_write(&c, 1);
sendchar(ch);
}
extern void $Super$$_sys_istty(void);
int $Sub$$_sys_istty(FILEHANDLE fh)
{
return 0; /* buffered output */
}
extern void $Super$$_sys_seek(void);
int $Sub$$_sys_seek(FILEHANDLE fh, long pos)
{
return -1; /* not supported */
}
extern void $Super$$_sys_flen(void);
long $Sub$$_sys_flen(FILEHANDLE fh)
{
return -1; /* not supported */
}
extern void $Super$$_sys_exit(void);
long $Sub$$_sys_exit(FILEHANDLE fh)
{
return -1; /* not supported */
}
//eof
hope, it helps you, too.
Don't forget to initialize uart in main, or try to put initialization in _sys_open()