Interfacing LCD 4-bits mode with stm32F103RBT6

[SIDRI.1]

#include "stm32f10x.h"                  // Device header
#include "LCD.h"
#include "stdint.h"
#include <stdio.h>
 
 
void GPIO_Init(void)
{
	
	// Port B is used for I2C1 communication : SCL1-->PB6 / SDA1-->PB7
	
	RCC->APB2ENR |= RCC_APB2ENR_IOPBEN;
	
}
 
void DelayTimerUs1(int n){
	// 1 Mhz ---> 1Us
	//ARR = n (n=1 --> 1us) (n=2 --> 2us) ....
// n = 30000 for 30ms delay
	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))) {}
		}
	TIM2->SR &=~ (1<<0);
		
	TIM2->CR1 &=~ TIM_CR1_CEN;
	}
 
void I2C1_Init(void)
	
{
	
	RCC->APB1ENR &=~RCC_APB1ENR_I2C1EN; // Clear I2C1 
	I2C1->CR1 |= 0x00; // clear CR1 register
	I2C1->CR2 |= 0x00; // Clear CR2 register
	
	RCC->APB2ENR |= RCC_APB2ENR_IOPBEN;
	
	// Set PB6 and PB7 as AF push-pull 10MHz (p161)
	
	  GPIOB->CRL &=~ GPIO_CRL_MODE6_1 | GPIO_CRL_MODE7_1; 
	  GPIOB->CRL |=  GPIO_CRL_MODE6_0 | GPIO_CRL_MODE7_0;
	  GPIOB->CRL &=~ GPIO_CRL_CNF6_0  | GPIO_CRL_CNF7_0;
	  GPIOB->CRL |=  GPIO_CRL_CNF6_1  | GPIO_CRL_CNF7_1;
	
	RCC->APB1ENR |= RCC_APB1ENR_I2C1EN;  // Enable I2C1	
	
	I2C1->CR2 |= 36;
	I2C1->CCR |= 180;
	I2C1->TRISE |= 37;
	I2C1->CR1 |= I2C_CR1_ACK;
	// Enable Interrupt (not mandatory)
	//I2C1->CR2 |= I2C_CR2_ITBUFEN;
	//I2C1->CR2 |= I2C_CR2_ITEVTEN;
	
	// Enbale I2C1 Peripheral
	I2C1->CR1 |= I2C_CR1_PE;
	
}
void I2C_send (uint8_t slave_addr, uint8_t data) // data can be either a command or Data
	
{
	uint8_t temp;
	// Send START condition
	I2C1->CR1 |= I2C_CR1_START;
	
	// check START condtion send
	while (!(I2C1->SR1 & I2C_SR1_SB)) 
{} // if the SB flag is not 1, do nothing,this means that the START condtion was not sent yet
	
	//Transmit the slave addresse
		
	I2C1->DR = slave_addr; // 0x7E 
 
	while (!(I2C1->SR1 & I2C_SR1_ADDR))  {}  // wait for ADDR flag in status register, if there was a match for this slave address, clear flag	 
 
	temp = I2C1->SR2;  // clear ADDR flag by reading SR2
			
			I2C1->DR = data;
			
		while(!(I2C1->SR1 & I2C_SR1_TXE))  {}	
			
		I2C1->CR1 = I2C_CR1_STOP;  // send another start condition if we have another byte
		
}
 
void LCD_cmd(char cmd){
	
	uint8_t CMD_H     = (cmd & 0xF0);   // Isoler Bit poids Fort de la cmd avec le masque 0x0F
  uint8_t CMD_Een   = (CMD_H |0x0C);  // Parametrer bit de config(poid faible), RE=1; E=1 ; RW=0; RS=0
	uint8_t CMD_Edis  = (CMD_H |0x08);  // RE=1; E=0 ; RW=0; RS=0
	uint8_t CMD_Shift = ((cmd<<4) & 0xF0);
	
	I2C_send (0x7E, CMD_Een);  // envoi de la cmd avec E=1
	I2C_send (0x7E, CMD_Edis); // envoi de la cmd avec E=0;
	
	I2C_send (0x7E, CMD_Shift | 0x0C); // envoi cmd decalée (4bits de poids faible) avec E=1
	I2C_send (0x7E, CMD_Shift | 0x08); // envoi cmd decalée (4bits de poids faible) avec E=0 
		
}
 
void LCD_Data( char Data){
	
	uint8_t data_H     = (Data & 0xF0);   // Isoler Bit poids Fort de la donnée avec le masque 0x0F
  uint8_t data_Een   = (data_H |0x0D);  // Parametrer bit de config(poid faible), RE=1; E=1 ; RW=0; RS=1
	uint8_t data_Edis  = (data_H |0x09);  // RE=1; E=0 ; RW=0; RS=1
	uint8_t data_Shift = ((Data<<4) & 0xF0);
	
	I2C_send (0x70, data_Een);  // envoi de la cmd avec E=1
	I2C_send (0x70, data_Edis); // envoi de la cmd avec E=0;
	
	I2C_send (0x70, data_Shift | 0x0D); // envoi data decalée avec E=1
	I2C_send (0x70, data_Shift | 0x09); // envoi data decalée avec E=0
 
}
 
void LCD_Init (void)
{
	
	GPIO_Init();
	
	DelayTimerUs1(10000);  // 10 ms delay
	LCD_cmd(0x30);
	DelayTimerUs1(10000);
	LCD_cmd(0x30);
	DelayTimerUs1(10000);
	LCD_cmd(0x30);
	DelayTimerUs1(10000);
	
	
	LCD_cmd (0x28);     // 0x20 tells the lcd controller that we want to communicate in 4-bit mode with 2 lines Row
	LCD_cmd (0x02);    //  Home (move cursor to top/left character position)
	//LCD_cmd (0x14);   //   Move cursor one character right
	
}

Hi there, please if anyone can give me a suggestion about my driver : i want to interface a 4-bit LCD HD44780 with I2C interface PCFpcf8574at, i have checked my code many times but it doesn't work : i'm frustrated, please if you have any suggestion