STM32通过IIC驱动MAX30102心率血氧传感器

STM32F103单片机通过IIC控制MAX30102心率血氧传感器

MAX30102的VCC引脚连接STM32F103mini单片机的5伏引脚，GND连接5伏对应的GND，SCL连PC12，SDA连PC11，INT连PA5。MAX30102的其他引脚没有用到。

本代码能够正常接收MAX30102心率血氧传感器返回的red与ir的数值，能够比较正常计算出心率血氧数值。当心率或血氧值的计算结果有误时对应的变量值为-999。

本文最后有源工程文件的下载链接。

工程文件中使用的delay.h，sys.h，usart.h，myiic.h均为正点原子官方提供的STM32F103mini单片机对应的源码，未做改动。

因此本文只粘贴新加的max30102.h(max30102驱动代码头文件)，max30102.c(max30102驱动代码)，algorithm.h(max30102心率血氧算法函数头文件)，algorithm.c(max30102心率血氧算法函数文件)，以及main.c的测试样例

main.c文件

#include "delay.h"
#include "sys.h"
#include "usart.h"
#include "myiic.h"
#include "max30102.h"
#include "algorithm.h"

#define MAX_BRIGHTNESS 255
#define START 100
#define DATA_LENGTH 500


uint32_t aun_ir_buffer[DATA_LENGTH]; //IR LED sensor data
int32_t n_ir_buffer_length;    //data length
uint32_t aun_red_buffer[DATA_LENGTH];    //Red LED sensor data
int32_t n_sp02; //SPO2 value
int8_t ch_spo2_valid;   //indicator to show if the SP02 calculation is valid
int32_t n_heart_rate;   //heart rate value
int8_t  ch_hr_valid;    //indicator to show if the heart rate calculation is valid
uint8_t uch_dummy;


 int main(void)
 { 
	uint32_t un_min, un_max, un_prev_data;  //variables to calculate the on-board LED brightness that reflects the heartbeats
	int i;
	int32_t n_brightness;
	float f_temp;
	
	NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);// 设置中断优先级分组2
	delay_init();	    	 //延时函数初始化	  
	uart_init(115200);	 	//串口初始化为115200
 	IIC_Init();		 	
	
	maxim_max30102_reset(); //resets the MAX30102
	// initialize serial communication at 115200 bits per second:
	//read and clear status register
	maxim_max30102_read_reg(0,&uch_dummy);
	maxim_max30102_init();  //initializes the MAX30102

	n_brightness=0;
	un_min=0x3FFFF;
	un_max=0;
	n_ir_buffer_length=DATA_LENGTH; //buffer length of 100 stores 5 seconds of samples running at 100sps
	//read the first 500 samples, and determine the signal range
	for(i=0;i<n_ir_buffer_length;i++)
	{
			while(PAin(5)==1);   //wait until the interrupt pin asserts
			maxim_max30102_read_fifo((aun_red_buffer+i), (aun_ir_buffer+i));  //read from MAX30102 FIFO	
			if(un_min>aun_red_buffer[i])
					un_min=aun_red_buffer[i];    //update signal min
			if(un_max<aun_red_buffer[i])
					un_max=aun_red_buffer[i];    //update signal max
			printf("red=%i,", aun_red_buffer[i]);
			printf("ir=%i\r\n", aun_ir_buffer[i]);
	}
	un_prev_data=aun_red_buffer[i];
	//calculate heart rate and SpO2 after first 500 samples (first 5 seconds of samples)
	maxim_heart_rate_and_oxygen_saturation(aun_ir_buffer, n_ir_buffer_length, aun_red_buffer, &n_sp02, &ch_spo2_valid, &n_heart_rate, &ch_hr_valid); 
	while(1)
	{
	  i=0;
		un_min=0x3FFFF;
		un_max=0;
		//dumping the first 100 sets of samples in the memory and shift the last 400 sets of samples to the top
		for(i=START;i<DATA_LENGTH;i++)
		{
				aun_red_buffer[i-START]=aun_red_buffer[i];
				aun_ir_buffer[i-START]=aun_ir_buffer[i];
				
				//update the signal min and max
				if(un_min>aun_red_buffer[i])
				un_min=aun_red_buffer[i];
				if(un_max<aun_red_buffer[i])
				un_max=aun_red_buffer[i];
		}
		//take 100 sets of samples before calculating the heart rate.
		for(i=400;i<DATA_LENGTH;i++)
		{
				un_prev_data=aun_red_buffer[i-1];
				while(PAin(5)==1);
				maxim_max30102_read_fifo((aun_red_buffer+i), (aun_ir_buffer+i));
		
				if(aun_red_buffer[i]>un_prev_data)//just to determine the brightness of LED according to the deviation of adjacent two AD data
				{
						f_temp=aun_red_buffer[i]-un_prev_data;
						f_temp/=(un_max-un_min);
						f_temp*=MAX_BRIGHTNESS;
						n_brightness-=(int)f_temp;
						if(n_brightness<0)
								n_brightness=0;
				}
				else
				{
						f_temp=un_prev_data-aun_red_buffer[i];
						f_temp/=(un_max-un_min);
						f_temp*=MAX_BRIGHTNESS;
						n_brightness+=(int)f_temp;
						if(n_brightness>MAX_BRIGHTNESS)
								n_brightness=MAX_BRIGHTNESS;
				}
				//send samples and calculation result to terminal program through UART
//				printf("red=%i,", aun_red_buffer[i]);
//				printf(" ir=%i,", aun_ir_buffer[i]);

		}
		maxim_heart_rate_and_oxygen_saturation(aun_ir_buffer, n_ir_buffer_length, aun_red_buffer, &n_sp02, &ch_spo2_valid, &n_heart_rate, &ch_hr_valid); 
		printf(" HR=%i,", n_heart_rate); 
		printf(" HRvalid=%i,", ch_hr_valid);
		printf(" SpO2=%i,", n_sp02);
		printf(" SPO2Valid=%i\r\n", ch_spo2_valid);
	}
}

max30102.h文件

/** \file max30102.h ******************************************************
*
* Project: MAXREFDES117#
* Filename: max30102.h
* Description: This module is an embedded controller driver header file for MAX30102
*
* Revision History:
*\n 1-18-2016 Rev 01.00 GL Initial release.
*\n
*
* --------------------------------------------------------------------
*
* This code follows the following naming conventions:
*
* char              ch_pmod_value
* char (array)      s_pmod_s_string[16]
* float             f_pmod_value
* int32_t           n_pmod_value
* int32_t (array)   an_pmod_value[16]
* int16_t           w_pmod_value
* int16_t (array)   aw_pmod_value[16]
* uint16_t          uw_pmod_value
* uint16_t (array)  auw_pmod_value[16]
* uint8_t           uch_pmod_value
* uint8_t (array)   auch_pmod_buffer[16]
* uint32_t          un_pmod_value
* int32_t *         pn_pmod_value
*
* ------------------------------------------------------------------------- */
/*******************************************************************************
* Copyright (C) 2016 Maxim Integrated Products, Inc., All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the name of Maxim Integrated
* Products, Inc. shall not be used except as stated in the Maxim Integrated
* Products, Inc. Branding Policy.
*
* The mere transfer of this software does not imply any licenses
* of trade secrets, proprietary technology, copyrights, patents,
* trademarks, maskwork rights, or any other form of intellectual
* property whatsoever. Maxim Integrated Products, Inc. retains all
* ownership rights.
*******************************************************************************
*/
#ifndef MAX30102_H_
#define MAX30102_H_

#include "stm32f10x.h"
#include "stdbool.h"

#define I2C_WRITE_ADDR 0xAE
#define I2C_READ_ADDR 0xAF

//register addresses
#define REG_INTR_STATUS_1 0x00
#define REG_INTR_STATUS_2 0x01
#define REG_INTR_ENABLE_1 0x02
#define REG_INTR_ENABLE_2 0x03
#define REG_FIFO_WR_PTR 0x04
#define REG_OVF_COUNTER 0x05
#define REG_FIFO_RD_PTR 0x06
#define REG_FIFO_DATA 0x07
#define REG_FIFO_CONFIG 0x08
#define REG_MODE_CONFIG 0x09
#define REG_SPO2_CONFIG 0x0A
#define REG_LED1_PA 0x0C
#define REG_LED2_PA 0x0D
#define REG_PILOT_PA 0x10
#define REG_MULTI_LED_CTRL1 0x11
#define REG_MULTI_LED_CTRL2 0x12
#define REG_TEMP_INTR 0x1F
#define REG_TEMP_FRAC 0x20
#define REG_TEMP_CONFIG 0x21
#define REG_PROX_INT_THRESH 0x30
#define REG_REV_ID 0xFE
#define REG_PART_ID 0xFF

bool maxim_max30102_init(void);
bool maxim_max30102_read_fifo(uint32_t *pun_red_led, uint32_t *pun_ir_led);
bool maxim_max30102_write_reg(uint8_t uch_addr, uint8_t uch_data);
bool maxim_max30102_read_reg(uint8_t uch_addr, uint8_t *puch_data);
bool maxim_max30102_reset(void);
#endif /*  MAX30102_H_ */

max30102.c文件

/** \file max30102.cpp ******************************************************
*
* Project: MAXREFDES117#
* Filename: max30102.cpp
* Description: This module is an embedded controller driver for the MAX30102
*
* Revision History:
*\n 1-18-2016 Rev 01.00 GL Initial release.
*\n
*/

#include "max30102.h"
#include "myiic.h"

#define max30102_WR_address 0xAE
bool maxim_max30102_write_reg(uint8_t uch_addr, uint8_t uch_data)
/**
* \brief        Write a value to a MAX30102 register
* \par          Details
*               This function writes a value to a MAX30102 register
*
* \param[in]    uch_addr    - register address
* \param[in]    uch_data    - register data
*
* \retval       true on success
*/
{
    /* 第1步：发起I2C总线启动信号 */
    IIC_Start();

    /* 第2步：发起控制字节，高7bit是地址，bit0是读写控制位，0表示写，1表示读 */
    IIC_Send_Byte(max30102_WR_address | I2C_WR);	/* 此处是写指令 */

    /* 第3步：发送ACK */
    if (IIC_Wait_Ack() != 0)
    {
        goto cmd_fail;	/* EEPROM器件无应答 */
    }

    /* 第4步：发送字节地址 */
    IIC_Send_Byte(uch_addr);
    if (IIC_Wait_Ack() != 0)
    {
        goto cmd_fail;	/* EEPROM器件无应答 */
    }

    /* 第5步：开始写入数据 */
    IIC_Send_Byte(uch_data);

    /* 第6步：发送ACK */
    if (IIC_Wait_Ack() != 0)
    {
        goto cmd_fail;	/* EEPROM器件无应答 */
    }

    /* 发送I2C总线停止信号 */
    IIC_Stop();
    return true;	/* 执行成功 */

cmd_fail: /* 命令执行失败后，切记发送停止信号，避免影响I2C总线上其他设备 */
    /* 发送I2C总线停止信号 */
    IIC_Stop();
    return false;
}

bool maxim_max30102_read_reg(uint8_t uch_addr, uint8_t *puch_data)
/**
* \brief        Read a MAX30102 register
* \par          Details
*               This function reads a MAX30102 register
*
* \param[in]    uch_addr    - register address
* \param[out]   puch_data    - pointer that stores the register data
*
* \retval       true on success
*/
{
    /* 第1步：发起I2C总线启动信号 */
    IIC_Start();

    /* 第2步：发起控制字节，高7bit是地址，bit0是读写控制位，0表示写，1表示读 */
    IIC_Send_Byte(max30102_WR_address | I2C_WR);	/* 此处是写指令 */

    /* 第3步：发送ACK */
    if (IIC_Wait_Ack() != 0)
    {
        goto cmd_fail;	/* EEPROM器件无应答 */
    }

    /* 第4步：发送字节地址， */
    IIC_Send_Byte((uint8_t)uch_addr);
    if (IIC_Wait_Ack() != 0)
    {
        goto cmd_fail;	/* EEPROM器件无应答 */
    }
    /* 第6步：重新启动I2C总线。下面开始读取数据 */
    IIC_Start();

    /* 第7步：发起控制字节，高7bit是地址，bit0是读写控制位，0表示写，1表示读 */
    IIC_Send_Byte(max30102_WR_address | I2C_RD);	/* 此处是读指令 */

    /* 第8步：发送ACK */
    if (IIC_Wait_Ack() != 0)
    {
        goto cmd_fail;	/* EEPROM器件无应答 */
    }

    /* 第9步：读取数据 */
    {
        *puch_data = IIC_Read_Byte();	/* 读1个字节 */

        IIC_NAck();	/* 最后1个字节读完后，CPU产生NACK信号(驱动SDA = 1) */
    }
    /* 发送I2C总线停止信号 */
    IIC_Stop();
    return true;	/* 执行成功 返回data值 */

cmd_fail: /* 命令执行失败后，切记发送停止信号，避免影响I2C总线上其他设备 */
    /* 发送I2C总线停止信号 */
    IIC_Stop();
    return false;
}

bool maxim_max30102_init(void)
/**
* \brief        Initialize the MAX30102
* \par          Details
*               This function initializes the MAX30102
*
* \param        None
*
* \retval       true on success
*/
{
		GPIO_InitTypeDef GPIO_InitStructure;
		RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA|RCC_APB2Periph_GPIOC,ENABLE);//使能PORTA,PORTC时钟
		GPIO_PinRemapConfig(GPIO_Remap_SWJ_JTAGDisable, ENABLE);//关闭jtag，使能SWD，可以用SWD模式调试
		GPIO_InitStructure.GPIO_Pin  = GPIO_Pin_5;//PA5
		GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; //PA5设置成浮空输入，接MAX30102的INT数据转换是否完成的信号引脚  
		GPIO_Init(GPIOA, &GPIO_InitStructure);//初始化GPIOA5
    if(!maxim_max30102_write_reg(REG_INTR_ENABLE_1, 0xc0)) // INTR setting
        return false;
    if(!maxim_max30102_write_reg(REG_INTR_ENABLE_2, 0x00))
        return false;
    if(!maxim_max30102_write_reg(REG_FIFO_WR_PTR, 0x00)) //FIFO_WR_PTR[4:0]
        return false;
    if(!maxim_max30102_write_reg(REG_OVF_COUNTER, 0x00)) //OVF_COUNTER[4:0]
        return false;
    if(!maxim_max30102_write_reg(REG_FIFO_RD_PTR, 0x00)) //FIFO_RD_PTR[4:0]
        return false;
    if(!maxim_max30102_write_reg(REG_FIFO_CONFIG, 0x6f)) //sample avg = 8, fifo rollover=false, fifo almost full = 17
        return false;
    if(!maxim_max30102_write_reg(REG_MODE_CONFIG, 0x03))  //0x02 for Red only, 0x03 for SpO2 mode 0x07 multimode LED
        return false;
    if(!maxim_max30102_write_reg(REG_SPO2_CONFIG, 0x2F)) // SPO2_ADC range = 4096nA, SPO2 sample rate (400 Hz), LED pulseWidth (411uS)
        return false;

    if(!maxim_max30102_write_reg(REG_LED1_PA, 0x17))  //Choose value for ~ 4.5mA for LED1
        return false;
    if(!maxim_max30102_write_reg(REG_LED2_PA, 0x17))  // Choose value for ~ 4.5mA for LED2
        return false;
    if(!maxim_max30102_write_reg(REG_PILOT_PA, 0x7f))  // Choose value for ~ 25mA for Pilot LED
        return false;
    return true;
}

bool maxim_max30102_read_fifo(uint32_t *pun_red_led, uint32_t *pun_ir_led)

/**
* \brief        Read a set of samples from the MAX30102 FIFO register
* \par          Details
*               This function reads a set of samples from the MAX30102 FIFO register
*
* \param[out]   *pun_red_led   - pointer that stores the red LED reading data
* \param[out]   *pun_ir_led    - pointer that stores the IR LED reading data
*
* \retval       true on success
*/
{
    uint32_t un_temp;
    uint8_t uch_temp;
    *pun_ir_led = 0;
    *pun_red_led = 0;
    maxim_max30102_read_reg(REG_INTR_STATUS_1, &uch_temp);
    maxim_max30102_read_reg(REG_INTR_STATUS_2, &uch_temp);



    /* 第1步：发起I2C总线启动信号 */
    IIC_Start();

    /* 第2步：发起控制字节，高7bit是地址，bit0是读写控制位，0表示写，1表示读 */
    IIC_Send_Byte(max30102_WR_address | I2C_WR);	/* 此处是写指令 */

    /* 第3步：发送ACK */
    if (IIC_Wait_Ack() != 0)
    {
        goto cmd_fail;	/* EEPROM器件无应答 */
    }

    /* 第4步：发送字节地址， */
    IIC_Send_Byte((uint8_t)REG_FIFO_DATA);
    if (IIC_Wait_Ack() != 0)
    {
        goto cmd_fail;	/* EEPROM器件无应答 */
    }


    /* 第6步：重新启动I2C总线。下面开始读取数据 */
    IIC_Start();

    /* 第7步：发起控制字节，高7bit是地址，bit0是读写控制位，0表示写，1表示读 */
    IIC_Send_Byte(max30102_WR_address | I2C_RD);	/* 此处是读指令 */

    /* 第8步：发送ACK */
    if (IIC_Wait_Ack() != 0)
    {
        goto cmd_fail;	/* EEPROM器件无应答 */
    }

    un_temp = IIC_Read_Byte();
    IIC_Ack();
    un_temp <<= 16;
    *pun_red_led += un_temp;
    un_temp = IIC_Read_Byte();
    IIC_Ack();
    un_temp <<= 8;
    *pun_red_led += un_temp;
    un_temp = IIC_Read_Byte();
    IIC_Ack();
    *pun_red_led += un_temp;

    un_temp = IIC_Read_Byte();
    IIC_Ack();
    un_temp <<= 16;
    *pun_ir_led += un_temp;
    un_temp = IIC_Read_Byte();
    IIC_Ack();
    un_temp <<= 8;
    *pun_ir_led += un_temp;
    un_temp = IIC_Read_Byte();
    IIC_Ack();
    *pun_ir_led += un_temp;
    *pun_red_led &= 0x03FFFF; //Mask MSB [23:18]
    *pun_ir_led &= 0x03FFFF; //Mask MSB [23:18]

    /* 发送I2C总线停止信号 */
    IIC_Stop();
    return true;
cmd_fail: /* 命令执行失败后，切记发送停止信号，避免影响I2C总线上其他设备 */
    /* 发送I2C总线停止信号 */
    IIC_Stop();
    return false;
}

bool maxim_max30102_reset()
/**
* \brief        Reset the MAX30102
* \par          Details
*               This function resets the MAX30102
*
* \param        None
*
* \retval       true on success
*/
{
    if(!maxim_max30102_write_reg(REG_MODE_CONFIG, 0x40))
        return false;
    else
        return true;
}

algorithm.h

/** \file algorithm.h ******************************************************
*
* Project: MAXREFDES117#
* Filename: algorithm.h
* Description: This module is the heart rate/SpO2 calculation algorithm header file
*
* Revision History:
*\n 1-18-2016 Rev 01.00 SK Initial release.
*\n
*
* --------------------------------------------------------------------
*
* This code follows the following naming conventions:
*
*\n char              ch_pmod_value
*\n char (array)      s_pmod_s_string[16]
*\n float             f_pmod_value
*\n int32_t           n_pmod_value
*\n int32_t (array)   an_pmod_value[16]
*\n int16_t           w_pmod_value
*\n int16_t (array)   aw_pmod_value[16]
*\n uint16_t          uw_pmod_value
*\n uint16_t (array)  auw_pmod_value[16]
*\n uint8_t           uch_pmod_value
*\n uint8_t (array)   auch_pmod_buffer[16]
*\n uint32_t          un_pmod_value
*\n int32_t *         pn_pmod_value
*
* ------------------------------------------------------------------------- */
/*******************************************************************************
* Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the name of Maxim Integrated
* Products, Inc. shall not be used except as stated in the Maxim Integrated
* Products, Inc. Branding Policy.
*
* The mere transfer of this software does not imply any licenses
* of trade secrets, proprietary technology, copyrights, patents,
* trademarks, maskwork rights, or any other form of intellectual
* property whatsoever. Maxim Integrated Products, Inc. retains all
* ownership rights.
*******************************************************************************
*/
#ifndef ALGORITHM_H_
#define ALGORITHM_H_
#include "stm32f10x.h"
#include "stdbool.h"

#define true 1
#define false 0
#define FS 50    //sampling frequency
#define BUFFER_SIZE  (FS* 3) 
#define MA4_SIZE  4 // DONOT CHANGE
#define min(x,y) ((x) < (y) ? (x) : (y))


static  int32_t an_x[ BUFFER_SIZE]; //ir
static  int32_t an_y[ BUFFER_SIZE]; //red

void maxim_heart_rate_and_oxygen_saturation(uint32_t *pun_ir_buffer, int32_t n_ir_buffer_length, uint32_t *pun_red_buffer, int32_t *pn_spo2, int8_t *pch_spo2_valid, int32_t *pn_heart_rate, int8_t *pch_hr_valid);
void maxim_find_peaks(int32_t *pn_locs, int32_t *n_npks,  int32_t  *pn_x, int32_t n_size, int32_t n_min_height, int32_t n_min_distance, int32_t n_max_num);
void maxim_peaks_above_min_height(int32_t *pn_locs, int32_t *n_npks,  int32_t  *pn_x, int32_t n_size, int32_t n_min_height);
void maxim_remove_close_peaks(int32_t *pn_locs, int32_t *pn_npks, int32_t *pn_x, int32_t n_min_distance);
void maxim_sort_ascend(int32_t  *pn_x, int32_t n_size);
void maxim_sort_indices_descend(int32_t  *pn_x, int32_t *pn_indx, int32_t n_size);

#endif /* ALGORITHM_H_ */

algorithm.c

/** \file algorithm.cpp ******************************************************
*
* Project: MAXREFDES117#
* Filename: algorithm.cpp
* Description: This module calculates the heart rate/SpO2 level
*
*
* --------------------------------------------------------------------
*
* This code follows the following naming conventions:
*
* char              ch_pmod_value
* char (array)      s_pmod_s_string[16]
* float             f_pmod_value
* int32_t           n_pmod_value
* int32_t (array)   an_pmod_value[16]
* int16_t           w_pmod_value
* int16_t (array)   aw_pmod_value[16]
* uint16_t          uw_pmod_value
* uint16_t (array)  auw_pmod_value[16]
* uint8_t           uch_pmod_value
* uint8_t (array)   auch_pmod_buffer[16]
* uint32_t          un_pmod_value
* int32_t *         pn_pmod_value
*
* ------------------------------------------------------------------------- */
/*******************************************************************************
* Copyright (C) 2016 Maxim Integrated Products, Inc., All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* Except as contained in this notice, the name of Maxim Integrated
* Products, Inc. shall not be used except as stated in the Maxim Integrated
* Products, Inc. Branding Policy.
*
* The mere transfer of this software does not imply any licenses
* of trade secrets, proprietary technology, copyrights, patents,
* trademarks, maskwork rights, or any other form of intellectual
* property whatsoever. Maxim Integrated Products, Inc. retains all
* ownership rights.
*******************************************************************************
*/

#include "algorithm.h"

//uch_spo2_table is approximated as  -45.060*ratioAverage* ratioAverage + 30.354 *ratioAverage + 94.845 ;
const uint8_t uch_spo2_table[184] = { 95, 95, 95, 96, 96, 96, 97, 97, 97, 97, 97, 98, 98, 98, 98, 98, 99, 99, 99, 99,
                                      99, 99, 99, 99, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100,
                                      100, 100, 100, 100, 99, 99, 99, 99, 99, 99, 99, 99, 98, 98, 98, 98, 98, 98, 97, 97,
                                      97, 97, 96, 96, 96, 96, 95, 95, 95, 94, 94, 94, 93, 93, 93, 92, 92, 92, 91, 91,
                                      90, 90, 89, 89, 89, 88, 88, 87, 87, 86, 86, 85, 85, 84, 84, 83, 82, 82, 81, 81,
                                      80, 80, 79, 78, 78, 77, 76, 76, 75, 74, 74, 73, 72, 72, 71, 70, 69, 69, 68, 67,
                                      66, 66, 65, 64, 63, 62, 62, 61, 60, 59, 58, 57, 56, 56, 55, 54, 53, 52, 51, 50,
                                      49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 31, 30, 29,
                                      28, 27, 26, 25, 23, 22, 21, 20, 19, 17, 16, 15, 14, 12, 11, 10, 9, 7, 6, 5,
                                      3, 2, 1
                                    } ;


void maxim_heart_rate_and_oxygen_saturation(uint32_t *pun_ir_buffer, int32_t n_ir_buffer_length, uint32_t *pun_red_buffer, int32_t *pn_spo2, int8_t *pch_spo2_valid,
        int32_t *pn_heart_rate, int8_t *pch_hr_valid)
/**
* \brief        Calculate the heart rate and SpO2 level
* \par          Details
*               By detecting  peaks of PPG cycle and corresponding AC/DC of red/infra-red signal, the an_ratio for the SPO2 is computed.
*               Since this algorithm is aiming for Arm M0/M3. formaula for SPO2 did not achieve the accuracy due to register overflow.
*               Thus, accurate SPO2 is precalculated and save longo uch_spo2_table[] per each an_ratio.
*
* \param[in]    *pun_ir_buffer           - IR sensor data buffer
* \param[in]    n_ir_buffer_length      - IR sensor data buffer length
* \param[in]    *pun_red_buffer          - Red sensor data buffer
* \param[out]    *pn_spo2                - Calculated SpO2 value
* \param[out]    *pch_spo2_valid         - 1 if the calculated SpO2 value is valid
* \param[out]    *pn_heart_rate          - Calculated heart rate value
* \param[out]    *pch_hr_valid           - 1 if the calculated heart rate value is valid
*
* \retval       None
*/
{
    uint32_t un_ir_mean;
    int32_t k, n_i_ratio_count;
    int32_t i, n_exact_ir_valley_locs_count, n_middle_idx;
    int32_t n_th1, n_npks;
    int32_t an_ir_valley_locs[15] ;
    int32_t n_peak_interval_sum;

    int32_t n_y_ac, n_x_ac;
    int32_t n_spo2_calc;
    int32_t n_y_dc_max, n_x_dc_max;
    int32_t n_y_dc_max_idx, n_x_dc_max_idx;
    int32_t an_ratio[5], n_ratio_average;
    int32_t n_nume, n_denom ;

    // calculates DC mean and subtract DC from ir
    un_ir_mean = 0;
    for (k = 0 ; k < n_ir_buffer_length ; k++ ) un_ir_mean += pun_ir_buffer[k] ;
    un_ir_mean = un_ir_mean / n_ir_buffer_length ;

    // remove DC and invert signal so that we can use peak detector as valley detector
    for (k = 0 ; k < n_ir_buffer_length ; k++ )
        an_x[k] = -1 * (pun_ir_buffer[k] - un_ir_mean) ;

    // 4 pt Moving Average
    for(k = 0; k < BUFFER_SIZE - MA4_SIZE; k++)
    {
        an_x[k] = ( an_x[k] + an_x[k + 1] + an_x[k + 2] + an_x[k + 3]) / (int)4;
    }
    // calculate threshold
    n_th1 = 0;
    for ( k = 0 ; k < BUFFER_SIZE ; k++)
    {
        n_th1 +=  an_x[k];
    }
    n_th1 =  n_th1 / ( BUFFER_SIZE);
    if( n_th1 < 30) n_th1 = 30; // min allowed
    if( n_th1 > 60) n_th1 = 60; // max allowed

    for ( k = 0 ; k < 15; k++) an_ir_valley_locs[k] = 0;
    // since we flipped signal, we use peak detector as vSalley detector
    maxim_find_peaks( an_ir_valley_locs, &n_npks, an_x, BUFFER_SIZE, n_th1, 4, 15 );//peak_height, peak_distance, max_num_peaks
    n_peak_interval_sum = 0;
    if (n_npks >= 2)
    {
        for (k = 1; k < n_npks; k++) n_peak_interval_sum += (an_ir_valley_locs[k] - an_ir_valley_locs[k - 1] ) ;
        n_peak_interval_sum = n_peak_interval_sum / (n_npks - 1);
        *pn_heart_rate = (int32_t)( (FS * 60) / n_peak_interval_sum );
        *pch_hr_valid  = 1;
    }
    else
    {
        *pn_heart_rate = -999; // unable to calculate because # of peaks are too small
        *pch_hr_valid  = 0;
    }

    //  load raw value again for SPO2 calculation : RED(=y) and IR(=X)
    for (k = 0 ; k < n_ir_buffer_length ; k++ )
    {
        an_x[k] =  pun_ir_buffer[k] ;
        an_y[k] =  pun_red_buffer[k] ;
    }

    // find precise min near an_ir_valley_locs
    n_exact_ir_valley_locs_count = n_npks;

    //using exact_ir_valley_locs , find ir-red DC andir-red AC for SPO2 calibration an_ratio
    //finding AC/DC maximum of raw

    n_ratio_average = 0;
    n_i_ratio_count = 0;
    for(k = 0; k < 5; k++) an_ratio[k] = 0;
    for (k = 0; k < n_exact_ir_valley_locs_count; k++)
    {
        if (an_ir_valley_locs[k] > BUFFER_SIZE )
        {
            *pn_spo2 =  -999 ; // do not use SPO2 since valley loc is out of range
            *pch_spo2_valid  = 0;
            return;
        }
    }
    // find max between two valley locations
    // and use an_ratio betwen AC compoent of Ir & Red and DC compoent of Ir & Red for SPO2
    for (k = 0; k < n_exact_ir_valley_locs_count - 1; k++)
    {
        n_y_dc_max = -16777216 ;
        n_x_dc_max = -16777216;
        if (an_ir_valley_locs[k + 1] - an_ir_valley_locs[k] > 3)
        {
            for (i = an_ir_valley_locs[k]; i < an_ir_valley_locs[k + 1]; i++)
            {
                if (an_x[i] > n_x_dc_max)
                {
                    n_x_dc_max = an_x[i];
                    n_x_dc_max_idx = i;
                }
                if (an_y[i] > n_y_dc_max)
                {
                    n_y_dc_max = an_y[i];
                    n_y_dc_max_idx = i;
                }
            }
            n_y_ac = (an_y[an_ir_valley_locs[k + 1]] - an_y[an_ir_valley_locs[k] ] ) * (n_y_dc_max_idx - an_ir_valley_locs[k]); //red
            n_y_ac =  an_y[an_ir_valley_locs[k]] + n_y_ac / (an_ir_valley_locs[k + 1] - an_ir_valley_locs[k])  ;
            n_y_ac =  an_y[n_y_dc_max_idx] - n_y_ac;   // subracting linear DC compoenents from raw
            n_x_ac = (an_x[an_ir_valley_locs[k + 1]] - an_x[an_ir_valley_locs[k] ] ) * (n_x_dc_max_idx - an_ir_valley_locs[k]); // ir
            n_x_ac =  an_x[an_ir_valley_locs[k]] + n_x_ac / (an_ir_valley_locs[k + 1] - an_ir_valley_locs[k]);
            n_x_ac =  an_x[n_y_dc_max_idx] - n_x_ac;     // subracting linear DC compoenents from raw
            n_nume = ( n_y_ac * n_x_dc_max) >> 7 ; //prepare X100 to preserve floating value
            n_denom = ( n_x_ac * n_y_dc_max) >> 7;
            if (n_denom > 0  && n_i_ratio_count < 5 &&  n_nume != 0)
            {
                an_ratio[n_i_ratio_count] = (n_nume * 100) / n_denom ; //formular is ( n_y_ac *n_x_dc_max) / ( n_x_ac *n_y_dc_max) ;
                n_i_ratio_count++;
            }
        }
    }
    // choose median value since PPG signal may varies from beat to beat
    maxim_sort_ascend(an_ratio, n_i_ratio_count);
    n_middle_idx = n_i_ratio_count / 2;

    if (n_middle_idx > 1)
        n_ratio_average = ( an_ratio[n_middle_idx - 1] + an_ratio[n_middle_idx]) / 2; // use median
    else
        n_ratio_average = an_ratio[n_middle_idx ];

    if( n_ratio_average > 2 && n_ratio_average < 184)
    {
        n_spo2_calc = uch_spo2_table[n_ratio_average] ;
        *pn_spo2 = n_spo2_calc ;
        *pch_spo2_valid  = 1;//  float_SPO2 =  -45.060*n_ratio_average* n_ratio_average/10000 + 30.354 *n_ratio_average/100 + 94.845 ;  // for comparison with table
    }
    else
    {
        *pn_spo2 =  -999 ; // do not use SPO2 since signal an_ratio is out of range
        *pch_spo2_valid  = 0;
    }
}


void maxim_find_peaks( int32_t *pn_locs, int32_t *n_npks,  int32_t  *pn_x, int32_t n_size, int32_t n_min_height, int32_t n_min_distance, int32_t n_max_num )
/**
* \brief        Find peaks
* \par          Details
*               Find at most MAX_NUM peaks above MIN_HEIGHT separated by at least MIN_DISTANCE
*
* \retval       None
*/
{
    maxim_peaks_above_min_height( pn_locs, n_npks, pn_x, n_size, n_min_height );
    maxim_remove_close_peaks( pn_locs, n_npks, pn_x, n_min_distance );
    *n_npks = min( *n_npks, n_max_num );
}

void maxim_peaks_above_min_height( int32_t *pn_locs, int32_t *n_npks,  int32_t  *pn_x, int32_t n_size, int32_t n_min_height )
/**
* \brief        Find peaks above n_min_height
* \par          Details
*               Find all peaks above MIN_HEIGHT
*
* \retval       None
*/
{
    int32_t i = 1, riseFound = 0, holdOff1 = 0, holdOff2 = 0, holdOffThresh = 4;
    *n_npks = 0;

    while (i < n_size - 1)
    {
        if (holdOff2 == 0)
        {
            if (pn_x[i] > n_min_height && pn_x[i] > pn_x[i - 1])     // find left edge of potential peaks
            {
                riseFound = 1;
            }
            if (riseFound == 1)
            {
                if ((pn_x[i] < n_min_height) && (holdOff1 < holdOffThresh))     // if false edge
                {
                    riseFound = 0;
                    holdOff1 = 0;
                }
                else
                {
                    if (holdOff1 == holdOffThresh)
                    {
                        if ((pn_x[i] < n_min_height) && (pn_x[i - 1] >= n_min_height))
                        {
                            if ((*n_npks) < 15 )
                            {
                                pn_locs[(*n_npks)++] = i;   // peak is right edge
                            }
                            holdOff1 = 0;
                            riseFound = 0;
                            holdOff2 = 8;
                        }
                    }
                    else
                    {
                        holdOff1 = holdOff1 + 1;
                    }
                }
            }
        }
        else
        {
            holdOff2 = holdOff2 - 1;
        }
        i++;
    }
}

void maxim_remove_close_peaks(int32_t *pn_locs, int32_t *pn_npks, int32_t *pn_x, int32_t n_min_distance)
/**
* \brief        Remove peaks
* \par          Details
*               Remove peaks separated by less than MIN_DISTANCE
*
* \retval       None
*/
{

    int32_t i, j, n_old_npks, n_dist;

    /* Order peaks from large to small */
    maxim_sort_indices_descend( pn_x, pn_locs, *pn_npks );

    for ( i = -1; i < *pn_npks; i++ )
    {
        n_old_npks = *pn_npks;
        *pn_npks = i + 1;
        for ( j = i + 1; j < n_old_npks; j++ )
        {
            n_dist =  pn_locs[j] - ( i == -1 ? -1 : pn_locs[i] ); // lag-zero peak of autocorr is at index -1
            if ( n_dist > n_min_distance || n_dist < -n_min_distance )
                pn_locs[(*pn_npks)++] = pn_locs[j];
        }
    }

    // Resort indices int32_to ascending order
    maxim_sort_ascend( pn_locs, *pn_npks );
}

void maxim_sort_ascend(int32_t  *pn_x, int32_t n_size)
/**
* \brief        Sort array
* \par          Details
*               Sort array in ascending order (insertion sort algorithm)
*
* \retval       None
*/
{
    int32_t i, j, n_temp;
    for (i = 1; i < n_size; i++)
    {
        n_temp = pn_x[i];
        for (j = i; j > 0 && n_temp < pn_x[j - 1]; j--)
            pn_x[j] = pn_x[j - 1];
        pn_x[j] = n_temp;
    }
}

void maxim_sort_indices_descend(  int32_t  *pn_x, int32_t *pn_indx, int32_t n_size)
/**
* \brief        Sort indices
* \par          Details
*               Sort indices according to descending order (insertion sort algorithm)
*
* \retval       None
*/
{
    int32_t i, j, n_temp;
    for (i = 1; i < n_size; i++)
    {
        n_temp = pn_indx[i];
        for (j = i; j > 0 && pn_x[n_temp] > pn_x[pn_indx[j - 1]]; j--)
            pn_indx[j] = pn_indx[j - 1];
        pn_indx[j] = n_temp;
    }
}

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