基于STM32的血氧儀(2)

一、簡(jiǎn)介

續(xù)上部分，我們已經(jīng)介紹了硬件設(shè)計(jì)和軟件框圖，接下來(lái)進(jìn)行軟件的編寫和實(shí)物演示

二、軟件設(shè)計(jì)

2.1軟件設(shè)計(jì)框圖

2.2 MAX30102驅(qū)動(dòng)編寫

2.2.1時(shí)鐘配置

設(shè)置系統(tǒng)時(shí)鐘源和分頻系數(shù)，使得STM32能夠正常工作。

__HAL_RCC_GPIOB_CLK_ENABLE();

2.2.2外設(shè)初始化

開(kāi)啟需要使用的外設(shè)時(shí)鐘，并進(jìn)行相應(yīng)的GPIO口、LCD等外設(shè)初始化。

	//使用模擬SPI
	
  GPIO_InitTypeDef GPIO_InitStruct = {0};
	
  GPIO_InitStruct.Pin = GPIO_PIN_13|GPIO_PIN_15;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

LCD屏初始化

void max30100_init(void)
{
	max30100_Bus_Write(0x06, 0x0b);  //mode configuration : temp_en[3]      MODE[2:0]=010 HR only enabled    011 SP02 enabled

	max30100_Bus_Write(0x01, 0xF0); //open all of interrupt
	max30100_Bus_Write(INTERRUPT_REG, 0x00); //all interrupt clear
	max30100_Bus_Write(0x09, 0x33); //r_pa=3,ir_pa=3
	
max30100_Bus_Write(0x02, 0x00); //set FIFO write Pointer reg = 0x00 for clear it
	max30100_Bus_Write(0x03, 0x00);	//set Over Flow Counter  reg = 0x00 for clear it
	max30100_Bus_Write(0x04, 0x0F);	//set FIFO Read Pointer  reg = 0x0f for   
											//waitting  write pointer eq read pointer   to   interrupts  INTERRUPT_REG_A_FULL
}

MAX30100驅(qū)動(dòng)程序

單片機(jī)通過(guò)I2C總線與傳感器模塊通信，獲取血氧、心率等數(shù)據(jù)。

//血液檢測(cè)信息更新
void blood_data_update(void)
{
	uint16_t temp_num=0;
	uint16_t fifo_word_buff[1][2];
	
	temp_num = max30100_Bus_Read(INTERRUPT_REG);
	
	//標(biāo)志位被使能時(shí) 讀取FIFO
	if (INTERRUPT_REG_A_FULL&temp_num)
	{
		HAL_GPIO_WritePin(GPIOC,GPIO_PIN_13,1);
		//讀取FIFO
		max30100_FIFO_Read(0x05,fifo_word_buff,1); //read the hr and spo2 data form fifo in reg=0x05
		
		//將數(shù)據(jù)寫入fft輸入并清除輸出
		for(int i = 0;i < 1;i++)
		{
			if(g_fft_index < FFT_N)
			{
				s1[g_fft_index].real = fifo_word_buff[i][0];
				s1[g_fft_index].imag= 0;
				s2[g_fft_index].real = fifo_word_buff[i][1];
				s2[g_fft_index].imag= 0;
				g_fft_index++;
			}
		}
		//信息更新標(biāo)志位
		g_blooddata.update++;
	}
	else
	{
		HAL_GPIO_WritePin(GPIOC,GPIO_PIN_13,0);
	}
}

1.硬件初始化模塊：包括時(shí)鐘配置、外設(shè)初始化等。

2.數(shù)據(jù)處理模塊：對(duì)采集到的數(shù)據(jù)進(jìn)行處理，計(jì)算出血氧值和心率等指標(biāo)，并將其顯示在LCD等界面上。

3.通信模塊：可以通過(guò)UART方式與其他設(shè)備進(jìn)行通信，將數(shù)據(jù)上傳至PC端進(jìn)行分析。

2.2.3計(jì)算血氧值和心率值

根據(jù)采集到的SPO2數(shù)據(jù)和心率數(shù)據(jù)，進(jìn)行相應(yīng)的計(jì)算，得出血氧值和心率值。

2.2.3.1 雙波長(zhǎng)光吸收比值計(jì)算

雙波長(zhǎng)光吸收比值計(jì)算是血氧值計(jì)算算法的第一步，它通過(guò)傳感器模塊采集的紅光和紅外線信號(hào)，計(jì)算出其在不同波長(zhǎng)下的吸收比值。一般需要進(jìn)行以下幾個(gè)步驟：

1.獲取紅光和紅外線信號(hào)：

temp_num = max30100_Bus_Read(INTERRUPT_REG);

2.血氧飽和度計(jì)算：根據(jù)雙波長(zhǎng)光吸收比值和相關(guān)系數(shù)，計(jì)算出血氧飽和度。

		//解平方
		for(int i = 0;i < FFT_N;i++) 
		{
			s1[i].real=sqrtf(s1[i].real*s1[i].real+s1[i].imag*s1[i].imag);
			s2[i].real=sqrtf(s2[i].real*s2[i].real+s2[i].imag*s2[i].imag);
		}

3.計(jì)算紅光和紅外線信號(hào)比值：將紅光和紅外線信號(hào)分別除以一個(gè)參考值（如環(huán)境光強(qiáng)度），得到其相對(duì)強(qiáng)度，再將兩者相除，得到紅光/紅外線信號(hào)比值。

 	       //心率計(jì)算
			uint16_t Heart_Rate = 60 * SAMPLES_PER_SECOND * 
														s2_max_index / FFT_N;
			
			g_blooddata.heart = Heart_Rate - 10;
			
			//血氧含量計(jì)算
			float sp02_num = (s2[s1_max_index].real * s1[0].real)
											/(s1[s1_max_index].real * s2[0].real);
			
			sp02_num = (1 - sp02_num) * SAMPLES_PER_SECOND + CORRECTED_VALUE;
			
			g_blooddata.SpO2 = sp02_num;

4.對(duì)比值進(jìn)行濾波

對(duì)紅光/紅外線信號(hào)比值進(jìn)行直流濾波處理，降低采集噪聲和干擾。

    //前8次求平均值
	for(int i = 0;i < 8;i++)
	{
		hbag  += s1[g_fft_index - 8 + i].real;
		hboag += s2[g_fft_index - 8 + i].real;
	}
		
	//直流濾波
	hbag_d = dc_filter(hbag,&hbdc) / 8;
	hboag_d = dc_filter(hboag,&hbodc) / 8;
	
	//高度數(shù)據(jù)
	float hbhight  = 0;
	float hbohight = 0;
	
	//比例與偏置
	hbhight  = (-hbag_d / 40.0) + 5;
	hbohight  = (-hboag_d / 40.0) + 5;
	
	//高度數(shù)據(jù)幅度限制
	hbhight = (hbhight > 27) ? 27 : hbhight;
	hbhight = (hbhight < 0) ?  0 : hbhight;
	
	hbohight = (hbohight > 27) ? 27 : hbohight;
	hbohight = (hbohight < 0) ?  0 : hbohight;
	
	//將數(shù)據(jù)發(fā)布到全局
	g_BloodWave.Hp = hbhight;
	g_BloodWave.HpO2 = hbohight;

2.2.4顯示數(shù)據(jù)

將計(jì)算得到的血氧值和心率值，顯示在LCD等界面上

//測(cè)試顯示血液信息
void tft_test_display(void)
{
	uint8_t str[50];

	if (g_blooddata.display == 1)
	{
		g_blooddata.display = 0;
		
		//顯示血氧信息
		sprintf((char *)str,"heart = %3d",g_blooddata.heart);
		Gui_DrawFont_GBK16(8,8,0x00FF,BLACK,str);
		
		//顯示心率信息
		sprintf((char *)str,"SpO2 = %3.1f",g_blooddata.SpO2);
		Gui_DrawFont_GBK16(8,26,0x00FF,BLACK,str);
		
		//顯示狀態(tài)信息
		if(g_blooddata.state)
		{
			sprintf((char *)str,"ERROR     ");
			Gui_DrawFont_GBK16(8,44,0xF000,BLACK,str);
		}
		else
		{
			sprintf((char *)str,"NORMAL    ");
			Gui_DrawFont_GBK16(8,44,0x07E0,BLACK,str);
		}
	}
}

三、實(shí)物演示