SPI1 stm32F103

[SIDRI.1]

Hi everyone,

So, i would like to test SPI1 communication on my stm32F103, using just the clock and MOSI line by sending 0x55 data on MOSI line ,

but when i see the traces on logic analyzer, i'm getting a weird values !

as seen in this capture picture, furthemore the clock signal is not symetric,

This is my code , if anyone has suggestion

Thank you .

#include "stm32f10x.h"                  // Device header
 
 
 
void Config_GPIO(void);
void SPI_config(void);
void DelayTimerUs(int n);
 
int main(){
	
	Config_GPIO();
	SPI_config();
	
	while(1){
	
	  while ( (SPI1->SR & SPI_SR_TXE)==0){}
			
			SPI1->DR = 0x55;
		DelayTimerUs(1000);
	}
	
}
 
void Config_GPIO(void){
 
// Enable RCC for APB2
RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;
RCC->APB2ENR |= RCC_APB2ENR_SPI1EN;	
	
// Ports configuration (AF)
	
//PA5-->clock AF push-pull
GPIOA->CRL |= GPIO_CRL_CNF5_1;
GPIOA->CRL &=~ GPIO_CRL_CNF5_0;	
GPIOA->CRL |= GPIO_CRL_MODE5_0 | 	GPIO_CRL_MODE5_1;
 
//PA7-->MOSI AF full-duplex Master  AF push-pull
GPIOA->CRL |= GPIO_CRL_CNF7_1;
GPIOA->CRL &=~ GPIO_CRL_CNF7_0;	
GPIOA->CRL |= GPIO_CRL_MODE7_0 | 	GPIO_CRL_MODE7_1;
 
//PA6-->MISO AF Input floating/Input pull-up
GPIOA->CRL &=~ GPIO_CRL_CNF6_1;
GPIOA->CRL |= GPIO_CRL_CNF6_0;	
GPIOA->CRL &=~ GPIO_CRL_MODE6_0 | GPIO_CRL_MODE6_1;
 
//PA4-->NSS AF push-pull
GPIOA->CRL |= GPIO_CRL_CNF4_1;
GPIOA->CRL &=~ GPIO_CRL_CNF4_0;	
GPIOA->CRL |= GPIO_CRL_MODE4_0 | 	GPIO_CRL_MODE4_1;
 
}
 
void SPI_config(void){
 
SPI1->CR1 &=~ SPI_CR1_BIDIMODE;  //2 line selected
SPI1->CR1 |= SPI_CR1_BIDIOE;  // Transmitter
SPI1->CR1 &=~ SPI_CR1_DFF;
SPI1->CR1 &=~SPI_CR1_RXONLY ; // Full duplex (Transmit and receive)
SPI1->CR1 &=~ SPI_CR1_SSM ;  //  Software slave management disabled 	
	
SPI1->CR1 |= SPI_CR1_LSBFIRST;	
	
// Baud rate control
SPI1->CR1 &=~ SPI_CR1_BR_0 ; // Set BR=32Khz 100   Fpclk=72Mhz/128
SPI1->CR1 |= SPI_CR1_BR_2 |SPI_CR1_BR_1  ;	
	
SPI1->CR1 |= SPI_CR1_MSTR; // Master configuration
SPI1->CR2 |= SPI_CR2_SSOE;
	
SPI1->CR1 &=~ SPI_CR1_CPHA | SPI_CR1_CPOL;	
	
	// Interruption flag for RX and TX enabled
SPI1->CR2 |= SPI_CR2_TXEIE | SPI_CR2_RXNEIE;	
	
	
// SPI1 enabled	
SPI1->CR1 |= SPI_CR1_SPE;	
	
}	
 
void DelayTimerUs(int n){
	// 1 Mhz ---> 1Us
	//ARR = n (n=1 --> 1us) (n=2 --> 2us) ....
 
	RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;
	TIM2->PSC = 36;
	TIM2->ARR = n;
	TIM2->CNT = 0;
	TIM2->CR1 = TIM_CR1_CEN;
	
	for( int i =0; i<n; i++){
		
		  while (!(TIM2->SR & (1<<0))) {} // while UIF flag =0
		}
	TIM2->SR &=~ (1<<0);
		
	TIM2->CR1 &=~ TIM_CR1_CEN;
	}