STM32 sends weird characters to COM ???

[aybala5]

Posted on October 06, 2014 at 17:36

Hello,

I send a char string to com port using sym32f4( with 3 pins only: GND VCC TX) and listen using ''hercules'' program finded on the net. I get weird characters, took a screanshot and uploaded as attachment. Can anyone help me, thnks.

[megahercas6]

Posted on October 06, 2014 at 17:45

Please set correct HSE values inside files;

stm32f4xx.h

#if !defined (HSE_VALUE) 
#define HSE_VALUE ((uint32_t)8000000) /*!< Value of the External oscillator in Hz */
#endif /* HSE_VALUE */

and also in system_config.c #define PLL_M 8

[Tesla DeLorean]

Posted on October 06, 2014 at 17:56

If not the PLL/HSE settings (EVAL boards use 25 MHz, DISCO boards use 8 MHz), then look at how you're connecting the USART, it uses CMOS levels, not RS232 levels. Review timing issues using a scope.

[aybala5]

Posted on October 06, 2014 at 18:11

Hello Mr. karpavicius,

First thanks for the response. I have no system_config.c file, i made the first change in stm32f4xx.h  from 25 to 8 but it didnt worked. I use stm32f4 discvory board send from PA2 (TX).

[aybala5]

Posted on October 06, 2014 at 18:15

#include ''stm32f4xx.h''
#include ''MPU6h''
#include <
stdio.h
>
void USART_puts(USART_TypeDef* USARTx, volatile char *s){
while(*s){
// wait until data register is empty
while( !(USARTx->SR & 0x00000040) );
USART_SendData(USARTx, *s);
*s++;
}
}
void init_usart(void){
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
/* enable peripheral clock for USART2 */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
/* GPIOA clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
/* GPIOA Configuration: USART2 TX on PA2 */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect USART2 pins to AF2 */
// TX = PA2
GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
USART_InitStructure.USART_BaudRate = 9600;
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(USART2, &USART_InitStructure);
USART_Cmd(USART2, ENABLE); // enable USART2
}
void Delay(__IO uint32_t nCount)
{
while(nCount--)
{
}
}
int main(void)
{
SystemInit();
init_usart();
MPU6050_I2C_Init();
MPU6050_Initialize();
if( MPU6050_TestConnection()== SUCCESS);
{
// connection success
}
/*
* <
pre
>
* 0 = +/- 250 degrees/sec
* 1 = +/- 500 degrees/sec
* 2 = +/- 1000 degrees/sec
* 3 = +/- 2000 degrees/sec
* </
pre
>
*/
MPU6050_SetFullScaleGyroRange(3);
while (1)
{ 
s16 AccelGyro[6]={0};
MPU6050_GetRawAccelGyro(AccelGyro);
s16 AccX;
s16 AccY;
s16 AccZ;
s16 GyrX;
s16 GyrY;
s16 GyrZ;
AccX=AccelGyro[0];
AccY=AccelGyro[1];
AccZ=AccelGyro[2];
GyrX=AccelGyro[3];
GyrY=AccelGyro[4];
GyrZ=AccelGyro[5];
int a;
//a=0x0008FFFF;
char str[50];
sprintf(str,''GX%dGY%dGZ%dAX%dAY%dAZ%dS

'',GyrX,GyrY,GyrZ,AccX,AccY,AccZ);
USART_puts(USART2,str);
//while(a--)
//{ 
//}
}
}

Mr Clive here is the code. Values come i monitor in watch1 but cannot send in corect way. I have no scope by the way :( What tests should i do ? Thanks.

[megahercas6]

Posted on October 06, 2014 at 18:23

can you make buffer yourself, fill it by hand, and send it ?

sometimes sprintf can do some fun stuff also why you don't have system_config.c file, do you made your own file for setting up registers, pll and so on ? if no, just add that file from discovery projects that can be downloaded from st.com one fun fact, sometimes changing optimization helps,

[Tesla DeLorean]

Posted on October 06, 2014 at 18:55

also why you don't have system_config.c file, do you made your own file for setting up registers, pll and so on ? if no, just add that file from discovery projects that can be downloaded from st.com

system_stm32f4xx.c ?

[aybala5]

Posted on October 06, 2014 at 18:57

I tested  USART_SendData(UART4, 0x49); // Send 'I' but i got [.

I used default libraries for stm32f4 but there is no  system_config.c instead there is system_stm32f4xx.c file. Whatever i changed the PLL_M =8 and HSE= 8Mhz but it didnt worked :(

[aybala5]

Posted on October 06, 2014 at 19:00

Yes Mr clive i have system_stm32f4xx.c. I saw one of your share code:

https://my.st.com/public/STe2ecommunities/mcu/Lists/STM32Discovery/Flat.aspx?RootFolder=%2Fpublic%2FSTe2ecommunities%2Fmcu%2FLists%2FSTM32Discovery%2FSTM32f4%20rs232%20IAR%20IDE&FolderCTID=0x01200200770978C69A1141439FE559EB459D75800084C20D8867EAD444A5987D47BE638E0F&currentviews=556

// STM32 UART4 (Tx PC.10, Rx PC.11) STM32F4 Discovery - sourcer32@gmail.com
// PC11 technically conflicts with SCLK on CS43L22
#include ''stm32f4_discovery.h''

......

USART_SendData(UART4, 0x49); // Send 'I'

.... I got '[' instead of 'I'. Dont know why. Is your example codes for stm32f4 Discv. Board ? If so can you share full code with config or just system_stm32f4xx file. So i can work with true config. Thanks.

[Tesla DeLorean]

Posted on October 06, 2014 at 19:17

C:\Keil\ARM\Examples\ST\STM32F4xx_DSP_StdPeriph_Lib_V1.4.0\Project\F4DISCO_USART2HELLO

See attached project

/public/STe2ecommunities/mcu/Lists/cortex_mx_stm32/Attachments/46669/F4DISCO_USART2HELLO.zip

// STM32F4-DISCO USART2 - sourcer32@gmail.com
#include ''stm32f4xx.h''
#include <
stdio.h
>
//****************************************************************************
void RCC_Configuration(void)
{
/* --------------------------- System Clocks Configuration -----------------*/
/* USART2 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
/* GPIOA clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
}
//****************************************************************************
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/*-------------------------- GPIO Configuration ----------------------------*/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect USART pins to AF */
GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2); // USART2_TX
GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2); // USART2_RX
}
//****************************************************************************
void USART2_Configuration(void)
{
USART_InitTypeDef USART_InitStructure;
/* USARTx configuration ------------------------------------------------------*/
/* USARTx configured as follow:
- BaudRate = 9600 baud
- Word Length = 8 Bits
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
*/
USART_InitStructure.USART_BaudRate = 9600;
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_Rx | USART_Mode_Tx;
USART_Init(USART2, &USART_InitStructure);
USART_Cmd(USART2, ENABLE);
}
//****************************************************************************
int main(void)
{
RCC_Configuration();
GPIO_Configuration();
USART2_Configuration();
puts(''Hello World!'');
while(1); // Don't want to exit
}
//****************************************************************************
#include <
rt_misc.h
>
#pragma import(__use_no_semihosting_swi)
struct __FILE { int handle; /* Add whatever you need here */ };
FILE __stdout;
FILE __stdin;
int fputc(int ch, FILE *f)
{
while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET);
USART_SendData(USART2, ch);
return(ch);
}
int fgetc(FILE *f)
{
char ch;
while(USART_GetFlagStatus(USART2, USART_FLAG_RXNE) == RESET);
ch = USART_ReceiveData(USART2);
return((int)ch);
}
int ferror(FILE *f)
{
/* Your implementation of ferror */
return EOF;
}
void _ttywrch(int ch)
{
while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET);
USART_SendData(USART2, ch);
}
void _sys_exit(int return_code)
{
label: goto label; /* endless loop */
}
//****************************************************************************
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t* file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf(''Wrong parameters value: file %s on line %d\r\n'', file, line) */
/* Infinite loop */
while (1)
{
}
}
#endif
//****************************************************************************

________________ Attachments : F4DISCO_USART2HELLO.zip : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I0vY&d=%2Fa%2F0X0000000bfk%2FyPTGIprn8KKkg_Wrd8jL_CDmYd3sgVTUmcOMsFpwWjY&asPdf=false