[STM32 learning] (14) two 74HC595 controls four nixie tube displays

74HC595 It is one of the commonly used chips in single chip microcomputer system. Its function is to convert serial signals into parallel signals , Commonly used in all kinds of digital tubes and dot matrix screen driver chips , Use 74HC595 Can save MCU mcu Of io Oral resources , use 3 individual io You can control 8 A pin of a nixie tube , He also has certain driving ability , It can eliminate the amplification circuit such as triode , So this chip is an artifact that drives digital tubes . Very widely used .

74HC595 Pin figure

74HC595 Pin function

The model of single chip microcomputer I choose is ：STM32L052K8 Series of low power chips , In fact, with F4 Series and F1 Series are the same .

Let's take a look at the wiring ：

You can clearly see the connection with the MCU from the above figure .

Two 595 Connect through cascading .

The two nixie tubes have a common anode

How to implement the code ？

So we can write 595 Driver program , as follows ：

/**********************************/
/**  The name of the function ：void HC595_Write_Data(unsigned char dis_data) **/
/**  Input parameters ：unsigned char dis_data  Data to be entered   */
/**  The functionality ： Write the data into 74HC595 in */
/** ****************************** **/
void HC595_Write_Data(unsigned char dis_data)
{
	unsigned char i;
	unsigned char temp;
	temp = dis_data;
	for(i=0;i<8;i++)    //     Loop writes the eight bits of a byte to the register in turn 
	{
		HAL_GPIO_WritePin(SRCLK_GPIO_Port,SRCLK_Pin,GPIO_PIN_RESET);// 	SRCLK Low level 
		if(temp & 0X80)
		{
			HAL_GPIO_WritePin(DATA_GPIO_Port,DATA_Pin,GPIO_PIN_SET);
		}
		else
		{
			HAL_GPIO_WritePin(DATA_GPIO_Port,DATA_Pin,GPIO_PIN_RESET);
		}
		temp = temp<<1;
		HAL_GPIO_WritePin(SRCLK_GPIO_Port,SRCLK_Pin,GPIO_PIN_RESET);	// 	SRCLK Low level 
		HAL_GPIO_WritePin(SRCLK_GPIO_Port,SRCLK_Pin,GPIO_PIN_SET);		// 	SRCLK High level 
	}
}

/****************************************/
/** The name of the function ：void Disp_out(void)*/
/** Function parameter ： No arguments */
/** The functionality ： Output the data written to the register to the port display */
/****************************************/
void Disp_out(void)
{
	HAL_GPIO_WritePin(RCLK_GPIO_Port,RCLK_Pin,GPIO_PIN_RESET);
	HAL_GPIO_WritePin(RCLK_GPIO_Port,RCLK_Pin,GPIO_PIN_SET);
}

IO The initialization function of the port is ：  Are set to push the output , Just don't pull up

static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOB_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOA, SRCLK_Pin|DATA_Pin, GPIO_PIN_SET);

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(RCLK_GPIO_Port, RCLK_Pin, GPIO_PIN_SET);

  /*Configure GPIO pins : SRCLK_Pin DATA_Pin */
  GPIO_InitStruct.Pin = SRCLK_Pin|DATA_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  /*Configure GPIO pin : RCLK_Pin */
  GPIO_InitStruct.Pin = RCLK_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(RCLK_GPIO_Port, &GPIO_InitStruct);

}

Now we want to dynamically display 1234

The main function code is ：

int main(void)
{
  
  MX_GPIO_Init();
  
  while (1)
  {
	
	HC595_Write_Data(0x01);	//	 Select the first digital tube 
	HC595_Write_Data(0x99);
	Disp_out(); 
	HAL_Delay(2);    //     Time delay 2ms
	 
	 
	HC595_Write_Data(0x02);	//	 Select the second digital tube 
	HC595_Write_Data(0xb0);
	Disp_out(); 
	HAL_Delay(2);    //     Time delay 2ms
	 
	
	HC595_Write_Data(0x04);	//	 Select the third digital tube 
	HC595_Write_Data(0xa4);	
	Disp_out();
	HAL_Delay(2);    //     Time delay 2ms
	 
	
	HC595_Write_Data(0x08);	//	 The fourth nixie tube 
	HC595_Write_Data(0xf9);	//	
	Disp_out();
	HAL_Delay(2);    //     Time delay 2ms
  }

}

The effect is as shown in the picture ：

 

 

There is a little hint ： When there is 595 When cascading , If there are two fast 595 cascade .

HC595_Write_Data(0x01);	//	 Select the first digital tube      The first data will be cascaded to the second block 595 In chip 
HC595_Write_Data(0x99);    //     The data sent later is the first piece 595 Data from the chip 
Disp_out();                 //     Finally, the data is transmitted to their respective ports , Carry out functional operation 

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